Mesoporous cobalt-manganese layered double hydroxides promote the activation of calcium sulfite for degradation and detoxification of metronidazole

Metronidazole (MNZ), a commonly used antibiotic, poses risks to water bodies and human health due to its potential carcinogenic, mutagenic, and genotoxic effects. In this study, mesoporous cobalt-manganese layered double hydroxides (CoxMny-LDH) with abundant oxygen vacancies (Ov) were successfully synthesized using the co-precipitation method and used to activate calcium sulfite (CaSO3) with slight soluble in water for MNZ degradation. The characterization results revealed that Co2Mn-LDH had higher specific areas and exhibited good crystallinity. Co2Mn-LDH/CaSO3 exhibited the best catalytic performance under optimal conditions, achieving a remarkable MNZ degradation efficiency of up to 98.1 % in only 8 min. Quenching experiments and electron paramagnetic resonance (EPR) tests showed that SO4•- and 1O2 played pivotal roles in the MNZ degradation process by activated CaSO3, while the redox cycles of Co2+/Co3+ and Mn3+/Mn4+ on the catalyst surface accelerated electron transfer, promoting radical generation. Three MNZ degradation routes were put forward based on the density functional theory (DFT) and liquid chromatography-mass spectrometer (LC-MS) analysis. Meanwhile, the toxicity analysis result demonstrated that the toxicity of intermediates post-catalytic reaction was decreased. Furthermore, the Co2Mn-LDH/CaSO3 system displayed excellent stability, reusability, and anti-interference capability, and achieved a comparably high removal efficiency across various organic pollutant water bodies. This study provides valuable insights into the development and optimization of effective heterogeneous catalysts for treating antibiotic-contaminated wastewater.

Fluorination modification enhanced the water resistance of Universitetet i Oslo-67 for multiple volatile organic compounds adsorption under high humidity conditions: Mechanism study

The construction of metal-organic frameworks (MOFs) with highly efficient capture for volatile organic compounds (VOCs) adsorption under humid conditions is a significant yet formidable task. Herein, series of fluorinated UiO-67 modified with trifluoroacetic acid (TFA) and 4-fluorobenzoic acid were successfully synthesized for VOCs adsorption under high humidity conditions. Experiments results showed that UiO-67 modified with 4-fluorobenzoic acid (67-F) presented excellent adsorption capacity of 345 mg/g for toluene adsorption and exhibited great water resistance (10.0 vol% H2O, 374 mg/g toluene adsorption capacity). Characterization results indicated that the introduction of 4-fluorobenzoic acid induced the competitive coordination between 4-fluorobenzoic acid and 4,4-biphenyl dicarboxylic acid (BPDC) with Zr4+, causing the formation of abundant defects to provide extra adsorption sites. Meanwhile, the benzene ring in 4-fluorobenzoic acid enhanced the π-π conjugation, causing the further promotion of VOCs adsorption capacity. More importantly, the water resistance mechanism was investigated and elucidated that the introduction of F decreased the surface energy of 67-F and its affinity with water. Meanwhile, the metal complex induced by the fluorinated modification produced an electron-dense pore environment, which greatly improved its chemical and water stability. This work provided a strategy for preparing an adsorbent with high water resistance for real-world VOCs adsorption at high humidity conditions.

Hollow-structured cobalt sulfide electrocatalyst for alkaline oxygen evolution reaction: Rational tuning of electronic structure using iron and fluorine dual-doping strategy

Utilizing renewable electricity for water electrolysis offers a promising way for generating high-purity hydrogen gases while mitigating the emission of environmental pollutants. To realize the water electrolysis, it is necessary to develop highly active and precious metal-free electrocatalyst for oxygen evolution reaction (OER) which incurs significant overpotential due to its complicated four-electron transfer mechanism. Hence, we propose a facile preparation method for hollow-structured Fe and F dual-doped CoS2 nanosphere (Fe-CoS2-F) as an efficient OER electrocatalyst. The uniform hollow and porous structure of Fe-CoS2-F enlarge the specific surface area and increase the number of exposed active sites. Furthermore, the Fe and F dual-dopants synergistically contributed to the adjustment of electronic structure, thereby promoting the adsorption/desorption of oxygen-containing reaction intermediates on active sites during the alkaline OER procedure. As a result, the prepared Fe-CoS2-F exhibits outstanding OER activity, characterized by a low overpotential of 298 mV to achieve a current density of 10 mA cm-2 and a Tafel slope as small as 46.0 mV dec-1. Based on computational theoretical calculations, the introduction of the dual-dopants into CoS2 structure reduce the excessively strong adsorption energy of reaction intermediate in the rate determining step, leading to effectively promoted electrocatalytic cycle for OER in alkaline environment. This study presents an effective strategy for preparing noble metal-free OER electrocatalysts with promising potential for large-scale industrial water electrolysis.

Comparative analysis of chlorinated disinfection byproducts formation from 4-nitrophenol and 2-amino-4-nitrophenol during UV/post-chlorination

Nitrophenol compounds (NCs) are widely distributed in water environments and regarded as important precursors of disinfection byproducts (DBPs). Herein, 4-nitrophenol and 2-amino-4-nitrophenol were selected as representative NCs to explore chlorinated DBPs (Cl-DBPs) formation during UV/post-chlorination. Dichloronitromethane (DCNM), trichloronitromethane (TCNM), dichloroacetonitrile (DCAN), and trichloromethane (TCM) were formed from 4-nitrophenol and 2-amino-4-nitrophenol during UV/post-chlorination, and the yields of individual Cl-DBPs from 2-amino-4-nitrophenol were higher than those from 4-nitrophenol. Meantime, increasing chlorine contact time, UV fluence, and free chlorine dose could enhance Cl-DBPs formation, while much higher values of the three factors might decrease the yields of Cl-DBPs. Besides, alkaline pH could decrease the yields of halonitromethane (HNMs) and DCAN but increase the yields of TCM. Also, higher concentrations of 4-nitrophenol and 2-amino-4-nitrophenol would induce more Cl-DBPs formation. Subsequently, the possible formation pathways of DCNM, TCNM, DCAN, and TCM form 4-nitrophenol and 2-amino-4-nitrophenol during UV/post-chlorination were proposed according to transformation products (TPs) and density functional theory (DFT) calculation. Notably, Cl-DBPs formed from 2-amino-4-nitrophenol presented higher toxicity than those from 4-nitrophenol. Among these generated Cl-DBPs, DCAN and TCNM posed higher cytotoxicity and genotoxicity, respectively. Furthermore, 4-nitrophenol, 2-amino-4-nitrophenol, and their TPs exhibited ecotoxicity. Finally, 4-nitrophenol and 2-amino-4-nitrophenol presented a high potential to produce DCNM, TCNM, DCAN, and TCM in actual waters during UV/post-chlorination, but the Cl-DBPs yields were markedly different from those in simulated waters. This work can help better understand Cl-DBPs formation from different NCs during UV/post-chlorination and is conducive to controlling Cl-DBPs formation.

Defect-engineering improves the activity of Metal-Organic frameworks for catalyzing hydroboration of Alkynes: A combination of experimental investigation and Density functional theory calculations

Defect-engineered metal-organic frameworks (DEMOFs) are emerging advanced materials. The construction of DEMOFs is of great significance; however, DEMOF-based catalysis remains unexplored. (E)-vinylboronates, an important building block for asymmetric synthesis, can be synthesized via the hydroboration of alkynes. However, the lack of high-performance catalysts considerably hinders their synthesis. Herein, a series of DEHKUST-1 (HKUST = Hong Kong University of Science and Technology) (Da-f) catalysts with missing occupation of linkers at Cu nodes were designed by partially replacing benzene-1,3,5-tricarboxylate (H3BTC) with defective connectors of pyridine-3,5-dicarboxylate (PYDC) to efficiently promote the hydroboration of alkynes. Results showed that the Dd containing 0.8 doping ratio of PYDC exhibited remarkable catalytic activity than the defect-free HKUST-1. This originated from the improved accessibility for reactants towards the Lewis acid active Cu sites of DEHKUST-1 due to the presence of plenty of rooms next to the Cu sites and enhanced coordination ability in such 'defective' HKUST-1. Dd had high selectivity (>99 %) and yield (>96 %) for (E)-vinylboronates and extensive functional group compatibility for terminal alkynes. Density functional theory (DFT) calculations were performed to elucidate the mechanism of hydroboration. Compared with that of defect-free HKUST-1, the low energy barrier of DEHKUST-1 can be attributed to the lower coordination number of Cu sites and enhanced accessibility of Cu active sites towards reagents.

Experimental and theoretical insight into carbamazepine degradation by chlorine-based advanced oxidation processes: Efficiency, energy consumption, mechanism and DBPs formation

Chlorine has been widely used in different advanced oxidation processes (AOPs) for micropollutants removal. In this study, different chlorine-based AOPs, namely medium pressure (MP) UV/chlorine, low pressure (LP) UV/chlorine, and in-situ chlorination, were compared for carbamazepine (CBZ) removal efficiency, energy consumption, and disinfection by-products (DBPs) formation. All three processes could achieve nearly 100% CBZ removal, while the reaction time needed by in-situ chlorination was double the time required by UV/chlorine processes. The energy consumed per magnitude of CBZ removed (EE/O) of MP UV/chlorine was 13 times higher than that of LP UV/chlorine, and relative to that of in-situ chlorination process. Accordingly, MP and LP UV/chlorine processes generated one to two orders of magnitude more hydroxyl radicals (•OH) and reactive chlorine species (RCS) than in-situ chlorination. Besides, RCS were the dominant reactive species, contributing to 78.3%, 75.6%, and 71.6% of CBZ removal in MP, LP UV/chlorine, and in-situ chlorination, respectively. According to the Gibbs free energy barriers between CBZ and RCS/•OH calculated based on density functional theory (DFT), RCS had more reaction routes with CBZ and showed lower energy barrier in the main CBZ degradation pathways like epoxidation and formation of iminostilbene. When applied to secondary wastewater effluent, UV/chlorine and in-situ chlorination produced overall DBPs ranging from 104.77 to 135.41 µg/L. However, the production of chlorate during UV/chlorine processes was 15 times higher than that during in-situ chlorination.

Molecular geochemistry of radium: A key to understanding cation adsorption reaction on clay minerals

Adsorption reactions of various cations on clay minerals have different effects on their environmental behaviors depending on the molecular-scale adsorption structure. Some cations form outer-sphere complexes via hydration, while others create inner-sphere complexes through dehydration. This preference dictates their environmental impact. However, the factors controlling these complex formations remain unclear. Furthermore, research on the adsorption preferences of radium (Ra) is lacking. Thus, this study conducted the first EXAFS study of Ra2+ adsorbed on clay minerals and showed that Ra2+ forms inner-sphere complexes on vermiculite, which can be surprising because Ra2+ is a divalent cation and prefers to be hydrated. In order to investigate the factors controlling the complex formations, this study conducted systematic EXAFS measurements and DFT calculations for alkali and alkaline earth metal cations. The results showed the importance of the size-matching effect between the adsorbed cation and the cavity of the tetrahedral sheets and that the complex formation can be estimated by the combination of the ionic radius and hydration enthalpy of the adsorbed cation. Furthermore, this study also analyzed environmental core samples. Their results showed the fixation of Ra2+ by clay minerals and the controlling factors can effectively predict cation environmental behavior.

Understanding and controlling the formation of single-atom site from supported Cu10 cluster by tuning CeO2 reducibility: Theoretical insight into the Gd-doping effect on electronic metal-support interaction

Controlling the formation of single-atom (SA) sites from supported metal clusters is an important and interesting issue to effectively improve the catalytic performance of heterogeneous catalysts. For extensively studied CO oxidation over metal/CeO2 systems, the SA formation and stabilization under reaction conditions is generally attributed to CO adsorption, however, the pivotal role played by the reducible CeO2 support and the underlying electronic metal-support interaction (EMSI) are not yet fully understood. Based on a ceria-supported Cu10 catalyst model, we performed density functional theory calculations to investigate the intrinsic SA formation mechanism and discussed the synergistic effect of Gd-doped CeO2 and CO adsorption on the SA formation. The CeO2 reducibility is tuned with doped Gd content ranging from 12.5 % ∼ 25 %. Based on ab initio thermodynamic and ab initio molecular dynamics, the critical condition for SA formation was identified as 21.875 % Gd-doped CeO2 with CO-saturated adsorption on Cu10. Electronic analysis revealed that the open-shell lattice Oδ- (δ < 2) generated by Gd doping facilitates the charge transfer from the bottom-corner Cu (Cubc) to CeO2. The CO-saturated adsorption further promotes this charge transfer process and enhances the EMSI between Cubc and CeO2, leading to the disintegration of Cubc from Cu10 and subsequent formation of the active SA site.

General Model for Predicting Response of Gas-Sensitive Materials to Target Gas Based on Machine Learning

Gas sensors play a crucial role in various industries and applications. In recent years, there has been an increasing demand for gas sensors in society. However, the current method for screening gas-sensitive materials is time-, energy-, and cost-consuming. Consequently, an imperative exists to enhance the screening efficiency. In this study, we proposed a collaborative screening strategy through integration of density functional theory and machine learning. Taking zinc oxide (ZnO) as an example, the responsiveness of ZnO to the target gas was determined quickly on the basis of the changes in the electronic state and structure before and after gas adsorption. In this work, the adsorption energy and electronic and structural characteristics of ZnO after adsorbing 24 kinds of gases were calculated. These computed features served as the basis for training a machine learning model. Subsequently, various machine learning and evaluation algorithms were utilized to train the fast screening model. The importance of feature values was evaluated by the AdaBoost, Random Forest, and Extra Trees models. Specifically, charge transfer was assigned importance values of 0.160, 0.127, and 0.122, respectively, ranking as the highest among the 11 features. Following closely was the d-band center, which was presumed to exert influence on electrical conductivity and, consequently, adsorption properties. With 5-fold cross-validation using the Extra Tree accuracy, the 24-sample data set achieved an accuracy of 88%. The 72-sample data set achieved an accuracy of 78% using multilayer perceptron after 5-fold cross-validation, with both data sets exhibiting low standard deviations. This verified the accuracy and reliability of the strategy, showcasing its potential for rapidly screening a material's responsiveness to the target gas.

Effect of Calcium and Phosphorus on Ammonium and Nitrate Nitrogen Adsorption onto Iron (Hydr)oxides Surfaces: CD-MUSIC Model and DFT Computation

Calcium (Ca2+) and phosphorous (PO43-) significantly influence the form and effectiveness of nitrogen (N), however, the precise mechanisms governing the adsorption of ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) are still lacking. This study employed batch adsorption experiments, charge distribution and multi-site complexation (CD-MUSIC) models and density functional theory (DFT) calculations to elucidate the mechanism by which Ca2+ and PO43- affect the adsorption of NH4+-N and NO3--N on the goethite (GT) surface. The results showed that the adsorption of NH4+-N on the GT exhibited an initial increase followed by a decrease as pH increased, peaking at a pH of 8.5. Conversely, the adsorption of NO3--N decreased with rising pH. According to the CD-MUSIC model, Ca2+ minimally affected the NH4+-N adsorption on the GT but enhanced NO3--N adsorption via electrostatic interaction, promoting the adsorption of ≡FeOH-NO3- and ≡Fe3O-NO3- species. Similarly, PO43- inhibited the adsorption of ≡FeOH-NO3- and ≡Fe3O-NO3- species. However, PO43- boosted NH4+-N adsorption by facilitating the formation of ≡Fe3O-NH4+ via electrostatic interaction and site competition. DFT calculations indicates that although bidentate phosphate (BP) was beneficial to stabilize NH4+-N than monodentate phosphate (SP), SP-NH4+ was the main adsorption configuration at pH 5.5-9.5 owing the prevalence of SP on the GT surface under site competition of NH4+-N. The results of CD-MUSIC model and DFT calculation were verified mutually, and provide novel insights into the mechanisms underlying N fixation and migration in soil.

Insight into the effective electrocatalytic sulfide removal from aqueous solutions using the surface oxidized stainless-steel anode and its desulfurization mechanism

The electrochemical oxidation removal method is effective for hydrogen sulfide (H2S) from wastewater. In this study, a surface corrosion treatment was used to achieve the Ni content regulating in the oxide film of the AISI 304 stainless steel (SS) surface. This made the low-cost SS substrate into a highly efficient electrochemical sulfide removal anode. The X-ray photoelectron spectroscopy (XPS) and linear sweeping voltammetry (LSV) results indicated the higher Ni content in the oxide film of surface-oxidized stainless steel (SOSS) attributed to the higher sulfide removal potential. Sulfide removal experiments results further demonstrated it, and the results showed that SS-150 (with 150 s anodic pretreatment) anodes reached the highest Ni content (about 69 %) and resulted in the best sulfide removal efficiency, achieving about 97 % within 48 h, which was increased by about 20 % compared to the untreated SS. Moreover, this study also demonstrated a strategy for in situ recovery of deposited sulfur on the anodes by cathodic recovery under -0.38 V vs. RHE to alleviate the electrode sulfur loaded problem which was the common issue limiting the sulfide removal process. Besides, the mechanism analysis by density functional theory (DFT) revealed that NiOOH was the main active site for SS-150 to obtain the faster sulfide removal rate, and the Mulliken charge population further illustrated the oxidation reaction of sulfide. The process shows the potential of the modified SS for continuous removal of hydrogen sulfide as sulfur from wastewater and recovery of the loaded sulfur through periodic shifting between anode sulfide oxidization and cathode-loaded sulfur restoration.

Complexation mechanism of Pb2+ on Al-substituted hematite: A modeling study and theoretical calculation

Hematite nanoparticles commonly undergoes isomorphic substitution of Al3+ in nature, while how the Al-substitution-induced morphological change, defective structure and newly generated Al-OH sites affect the adsorption behavior of hematite for contaminants remains poorly understood. Herein, the interfacial reactions between Al-substituted hematite and Pb2+ was investigated via CD-MUSIC modeling and DFT calculations. As the Al content increased from 0% to 9.4%, Al-substitution promoted the proportion of (001) facets and caused Fe vacancies on hematite, which increased the total active site density of hematite from 5.60 to 17.60 sites/nm2. The surface positive charge of hematite significantly increased from 0.096 to 0.418 C/m2 at pH 5.0 due to the increases in site density and proton affinity (logKH) of hematite under Al-substitution. The adsorption amount of hematite for Pb2+ increased from 3.92 to 9.74 mmol/kg at pH 5.0 and 20 μmol/L initial Pb2+ concentration with increasing Al content. More Fe vacancies may lead to a weaker adsorption energy (Ead) of hematite for Pb2+, while the Ead was enhanced at higher Al content. The adsorption affinity (logKPb) of bidentate Pb complexes slightly increased while that of tridentate Pb complexes decreased with increasing Al content due to the presence of ≡ AlOH-0.5 and ≡ Fe2AlO-0.5 sites. Tridentate Pb complexes were dominant species on the surface of pure hematite, while bidentate ones became more dominant with increasing Al content. The obtained model parameters and molecular scale information are of great importance for better describing and predicting the environmental fate of toxic heavy metals in terrestrial and aquatic environments.

New mechanistic insight into catalytic decomposition of dioxins over MnOx-CeO2/TiO2 catalysts: A combined experimental and density functional theory study

Elucidation of the catalytic decomposition mechanism of dioxins is pivotal in developing highly efficient dioxin degradation catalysts. In order to accurately simulate the whole molecular structure of dioxins, two model compounds, o-dichlorobenzene (o-DCB) and furan, were employed to represent the chlorinated benzene ring and oxygenated central ring within a dioxin molecule, respectively. Experiments and Density Functional Theory (DFT) calculations were combined to investigate the adsorption as well as oxidation of o-DCB and furan over MnOx-CeO2/TiO2 catalyst (denoted as MnCe/Ti). The results indicate that competitive adsorption exists between furan and o-DCB. The former exhibits superior adsorption capacity on MnCe/Ti catalyst at 100 °C - 150 °C, for it can adsorb on both surface metal atom and surface oxygen vacancies (Ov) via its O-terminal; while the latter adsorbs primarily by anchoring its Cl atom to surface Ov. Regarding oxidation, furan can be completely oxidized at 150 °C - 300 °C with a high CO2 selectivity (above 80 %). However, o-DCB cannot be totally oxidized and the resulting intermediates cause the deactivation of catalyst. Interestingly, the pre-adsorption of furan on catalyst surface can facilitate the catalytic oxidation of o-DCB below 200 °C, possibly because the dissociated adsorption of furan may form additional reactive oxygen species on catalyst surface. Therefore, this work provides new insights into the catalytic decomposition mechanism of dioxins as well as the optimization strategies for developing dioxin-degradation catalysts with high efficiency at low temperature.

Monoethanolamine enhanced iohexol degradation in the Co(II)/sulfite system: Nonnegligible role of complexation in accelerating cobalt redox cycling

Generation of sulfate radicals (SO4•-) from sulfite activation has emerged as a promising method for abatement of organic pollutants in the water and wastewater treatment. Co(II) has garnered attention due to its high catalytic activity in the sulfite activation, which is compromised by the slow Co(II)/Co(III) redox cycling. Regarding the regulation of Co(II) electronic structure via the complexation effect, monoethanolamine (MEA), a common chelator, is introduced into the Co(II)/sulfite system. MEA addition results in a significant improvement in iohexol abatement efficiency, increasing from 40% to 92%. The superior iohexol abatement relies on the involvement of SO4•-, hydroxyl radicals (HO•) and Co(IV). Hydrogen radical (•H) is unexpectedly detected, acting as a strong reducing agent, contributing to the reduction of Co(III). This enhancement of sulfite activation by MEA is due to the formation of the Co(II)-MEA complex, in which the complexation ratio of Co(II) and MEA is critical. Electrochemical characterization and theoretical calculations demonstrate that the complexation can facilitate the Co(II)/Co(III) redox cycling with the concomitant enhancement of sulfite activation. This work provides a new insight into the Co(II)/sulfite system in the presence of organic ligands.

Investigation of hydrogen bonds in proton transfer complexes derived from the reaction of 2- and 4-(N,N-dimethylamino)pyridines with chloranilic acid

New complexes of 2-(N,N-dimethylamino)pyridine with chloranilic acid (2-DMAP + CLA) and 4-(N,N-dimethylamino)pyridine with chloranilic acid (4-DMAP + CLA) were synthesized and characterized by single crystal X-ray diffraction, infrared spectroscopy, thermal analysis methods and 1H, 13C and 15N NMR spectroscopy. The NMR spectroscopies were carried out in both, DMSO solution and in the solid state (CPMAS NMR). The 2-DMAP + CLA and 4-DMAP + CLA complexes crystallize in centrosymmetric P-1 and P21/c space group, respectively. In both complexes, the phenomenon of proton transfer is observed, which results in the formation of strong N+-H···O- hydrogen bonds. Thermal decompositions of 2-DMAP + CLA and 4-DMAP + CLA complexes were studied by thermogravimetric analysis. Temperature dependent IR spectra revealed that methyl groups of 4-DMAP + CLA perform fast stochastic reorientational motion at room temperature which is slowed on cooling while in 2-DMAP + CLA reonrientational motion of CH3 groups is much slower due to steric effects.

Supramolecular assemblies of citalopram and escitalopram in β-cyclodextrin dimeric cavity: Crystallographic and theoretical insights

Cyclodextrin (CD) encapsulation improves physicochemical and pharmacological properties of selective serotonin reuptake inhibitors (SSRIs), which are efficacious in treating depression, a global mental health problem. Here, we scrutinize β-CD inclusion complexes with racemate citalopram (rac-CTP; 1) and escitalopram ((S)-CTP; 2) by combined single-crystal X-ray diffraction and DFT full-geometry optimization. X-ray analysis unveiled that the 2:2 inclusion complexes of 1 and 2 with similar inclusion modes and topologies are stabilized by various intermolecular interactions of host-guest CH···π, host-host OH···O H-bonds, and guest-guest F···F in the tail-to-tail dimeric asymmetric unit. In the crystals, these dimers are stacked on top of each other, yielding similar channel structures of distinct crystal symmetries, triclinic, P1 (1) and monoclinic, P21 (2), which are further maintained by guest-guest π···π and CN···π interactions. The thermodynamic stabilities evaluated by DFT calculation indicate the vital role of weak intermolecular interactions in the formation and stabilization of the β-CD monomeric and dimeric inclusion complexes. This study provides crystallographic and theoretical evidence for the improved stability and the masked bitterness of CTP through β-CD encapsulation as patented previously and suggests the pharmaceutical implications in the drug delivery and enantioseparation.

Tix+ in-situ intercalation and interlayer modification via titanium foil/vanadium ion solution interface of VO2.375 as sulfur-wrapped matrix enabling long-life lithium sulfur battery

Lithium sulfur battery (LSB) has great potential as a promising next-generation energy storage system owing to ultra-high theoretical specific capacity and energy density. However, the polysulfide shuttle effect and slow redox kinetics are recognized the most stumbling blocks on the way of commercializing LSB. On this account, for the first time, we use Tix+ in-situ intercalation strategy via titanium foil/vanadium ion (V5+) solution interface to modify the layer of vanadium oxide for long cycle LSB. The inserted Tix+ strengthens interlayer interaction and enhances lithium-ion mobility rate. Meanwhile, based on density functional theory (DFT) calculation, the mixed valence of V5+/V4+ in the vanadium oxide structure reduces the stress and strain of lithium-ion intercalation through the interlayer support of titanium ions (Tix+). Also, Tix+ refines the structural stability of the sulfur wrapped composite matrix so as to facilitate the LiPSs transformation, and improve the electrochemical performances. Consequently, the Ti-VO2.375/S cathode delivers a lower capacity decay of 0.037 % per cycle over 1500 cycles with a stable coulombic efficiency around 100 %.

Three-Phase-Heterojunction Cu/Cu2O-Sb2O3 Catalyst Enables Efficient CO2 Electroreduction to CO and High-Performance Aqueous Zn-CO2 Battery

Zn-CO2 batteries are excellent candidates for both electrical energy output and CO2 utilization, whereas the main challenge is to design electrocatalysts for electrocatalytic CO2 reduction reactions with high selectivity and low cost. Herein, the three-phase heterojunction Cu-based electrocatalyst (Cu/Cu2O-Sb2O3-15) is synthesized and evaluated for highly selective CO2 reduction to CO, which shows the highest faradaic efficiency of 96.3% at -1.3 V versus reversible hydrogen electrode, exceeding the previously reported best values for Cu-based materials. In situ spectroscopy and theoretical analysis indicate that the Sb incorporation into the three-phase heterojunction Cu/Cu2O-Sb2O3-15 nanomaterial promotes the formation of key *COOH intermediates compared with the normal Cu/Cu2O composites. Furthermore, the rechargeable aqueous Zn-CO2 battery assembled with Cu/Cu2O-Sb2O3-15 as the cathode harvests a peak power density of 3.01 mW cm-2 as well as outstanding cycling stability of 417 cycles. This research provides fresh perspectives for designing advanced cathodic electrocatalysts for rechargeable Zn-CO2 batteries with high-efficient electricity output together with CO2 utilization.

Structure and Chiroptical Properties of Anthra[1,2-a]anthracene-1-yl Dimers as New Biaryls

Dimers of anthra[1,2-a]anthracene-1-yl units and its mesityl derivative were synthesized by Ni(0)-mediated coupling of the corresponding chloro derivatives as new biaryls. The X-ray analysis and DFT calculations revealed that two polycyclic aromatic units with nonplanar deformations took a twisted conformation about the single bond as a chiral axis. Enantiomers of the nonsubstituted compound were resolved by chiral HPLC, and the enantiopure samples showed intense Cotton effects at 321 nm in the circular dichroism (CD) spectra and emission bands at 449 nm in the circularly polarized luminescence (CPL) spectra with dissymmetry factor of |glum| 3.6×10-3. The absolute stereochemistry of this biaryl was determined by the theoretical calculation of CD spectrum by the time-dependent DFT method. The barrier to enantiomerization was determined to be 108 kJ mol-1 at 298 K. The dynamic process proceeded via a stepwise mechanism involving the helical inversion of each aromatic unit and the rotation about the biaryl axis as analyzed by the DFT calculations.

Chiral Osmium(II)/Salox Species Enabled Enantioselective γ-C(sp3)-H Amidation: Integrated Experimental and Computational Validation For the Ligand Design and Reaction Development

Herein, multiple types of chiral Os(II) complexes have been designed to address the appealing yet challenging asymmetric C(sp3)-H functionalization, among which the Os(II)/Salox species is found to be the most efficient for precise stereocontrol in realizing the asymmetric C(sp3)-H amidation. As exemplified by the enantioenriched pyrrolidinone synthesis, such tailored Os(II)/Salox catalyst efficiently enables an intramolecular site-/enantioselective C(sp3)-H amidation in the γ-position of dioxazolone substrates, in which benzyl, propargyl and allyl groups bearing various substituted forms are well compatible, affording the corresponding chiral γ-lactam products with good er values (up to 99 : 1) and diverse functionality (>35 examples). The unique performance advantage of the developed chiral Os(II)/Salox system in terms of the catalytic energy profile and the chiral induction has been further clarified by integrated experimental and computational studies.

De novo antioxidant peptide design via machine learning and DFT studies

Antioxidant peptides (AOPs) are highly valued in food and pharmaceutical industries due to their significant role in human function. This study introduces a novel approach to identifying robust AOPs using a deep generative model based on sequence representation. Through filtration with a deep-learning classification model and subsequent clustering via the Butina cluster algorithm, twelve peptides (GP1-GP12) with potential antioxidant capacity were predicted. Density functional theory (DFT) calculations guided the selection of six peptides for synthesis and biological experiments. Molecular orbital representations revealed that the HOMO for these peptides is primarily localized on the indole segment, underscoring its pivotal role in antioxidant activity. All six synthesized peptides exhibited antioxidant activity in the DPPH assay, while the hydroxyl radical test showed suboptimal results. A hemolysis assay confirmed the non-hemolytic nature of the generated peptides. Additionally, an in silico investigation explored the potential inhibitory interaction between the peptides and the Keap1 protein. Analysis revealed that ligands GP3, GP4, and GP12 induced significant structural changes in proteins, affecting their stability and flexibility. These findings highlight the capability of machine learning approaches in generating novel antioxidant peptides.

Correction for the calculated XANES spectra of 1,4,7,10-alkyltetracenes considering the total electron yield (TEY) efficiency of sp2- and sp3-carbon atoms

The calculated X-ray-absorption-near-edge-structure (XANES) spectra in the CK region of 1,4,7,10-alkyltetracenes, which are composed of both sp2-C atoms in the tetracene ring and sp3-C atoms in the alkyl-chains, can be corrected by considering the total electron yield (TEY) efficiency of sp3-C relative to sp2-C. In the correction, the previously measured TEY efficiency of k = 0.51 is applied to the calculated transition probabilities for sp3-C atoms. Then the calculated CK-XANES obtained from density functional theory (DFT) calculations can well reproduce the measured TEY-CK-XANES. Especially, the calculated π*/σ* peak intensity ratios are in good agreement with the measured ones. This suggests that a similar correction for the calculated XANES is necessary for compounds composed of multi-components with different TEY efficiencies.

Resource recovery and regeneration strategies for spent lithium-ion batteries: Toward sustainable high-value cathode materials

Traditional cathode recycling methods have become outdated amid growing concerns for high-value output and environmental friendliness in spent Li-ion battery (LIB) recycling. Our study presents a closed-loop approach that involves selective sulfurization roasting, water leaching, and regeneration, efficiently transforming spent ternary Li batteries (i.e., NCM) into high-performance cathode materials. By combining experimental investigations with density functional theory (DFT) calculations, we elucidate the mechanisms within the NCM-C-S roasting system, providing a theoretical foundation for selective sulfidation. Utilizing in situ X-ray diffraction techniques and a series of consecutive experiments, the study meticulously tracks the evolution of regenerating cathode materials that use transition metal sulfides as their primary raw materials. The Li-rich regenerated NCM exhibits exceptional electrochemical performance, including long-term cycling, high-rate capabilities, reversibility, and stability. The closed-loop approach highlights the sustainability and environmental friendliness of this recycling process, with potential applications in other cathode materials, such as LiCoO2 and LiMn2O4. Compared with traditional methods, this short process approach avoids the complexity of leaching, solvent extraction, and reverse extraction, significantly increasing metal utilization and Li recovery rates while reducing pollution and resource waste.

DFT Predirected Molecular Engineering Design of Donor-Acceptor Structured g-C3 N4 for Efficient Photocatalytic Tetracycline Abatement

The photocatalytic environmental decontamination ability of carbon nitride (g-C3 N4 , CN) typically suffers from their inherent structural defects, causing rapid recombination of photogenerated carriers. Conjugating CN with tailored donor-acceptor (D-A) units to counteract this problem through electronic restructuring becomes a feasible strategy, where confirmation by density functional theory (DFT) calculations becomes indispensable. Herein, DFT is employed to predirect the copolymerization modification of CN by benzene derivatives, screening benzaldehyde as the optimal electron-donating candidate for the construction of reoriented intramolecular charge transfer path. Experimental characterization and testing corroborate the formation of a narrowed bandgap as well as high photoinduced carrier separation. Consequently, the optimal BzCN-2 exhibited superior photocatalytic capacity in application for tetracycline hydrochloride degradation, with 3.73 times higher than that of CN. Besides, the BzCN-2-based photocatalytic system is determined to have a toxicity-mitigating effect on TC removal via T.E.S.T and prefers the removal of dissociable TC2- species under partial alkalinity. This work provides insight into DFT guidance for the design of D-A conjugated polymer and its application scenarios in photocatalytic decontamination.

Self-Supported Mn-Ni3Se2 Electrocatalysts for Water and Urea Electrolysis for Energy-Saving Hydrogen Production

Recently, there has been a huge research interest in developing robust, efficient, low-cost, and earth-abundant materials for water and urea electrolysis for hydrogen (H2) generation. Herein, we demonstrate the facile hydrothermal synthesis of self-supported Mn-Ni3Se2 on Ni foam for overall water splitting under wide pH conditions. With the optimized concentration of Mn in Ni3Se2, the overpotential for hydrogen evolution, oxygen evolution, and urea oxidation is significantly reduced by an enhanced electrochemical active surface area. Different electronic states of metal elements also produce a synergistic effect, which accelerates the rate of electrochemical reaction for water and urea electrolysis. Owing to the chemical robustness, Mn-doped Ni3Se2 shows excellent stability for long time duration, which is important for its practical applications. A two-electrode electrolyzer exhibits low cell voltages of 2.02 and 1.77 V for water and urea electrolysis, respectively, to generate a current density of 100 mA/cm2. Finally, the prepared nanostructured Mn-Ni3Se2@NF acts as an electrocatalyst for overall water splitting under wide pH conditions and urea electrolysis for energy-saving hydrogen production and wastewater treatment.

Unveiling the Morphology of Carbon-Supported Ru Nanoparticles by Multiscale Modeling

Simulating the behavior of metal nanoparticles on supports is crucial for boosting their catalytic performance and various nanotechnology applications; however, such simulations are limited by the conflicts between accuracy and efficiency. Herein, we introduce a multiscale modeling strategy to unveil the morphology of Ru supported on pristine and N-doped graphene. Our multiscale modeling started with the electronic structures of a supported Ru single atom, revealing the strong metal-support interaction around pyridinic nitrogen sites. To determine the stable configurations of Ru2-13 clusters on three different graphene supports, global energy minimum searches were performed. The sintering of the global minimum Ru13 clusters on supports was further simulated by ab initio molecular dynamics (AIMD). The AIMD data set was then collected for deep potential molecular dynamics to study the melting of Ru nanoparticles. This study presents comprehensive descriptions of carbon-supported Ru and develops modeling approaches that bridge different scales and can be applied to various supported nanoparticle systems.

Mechanochemically functionalized and fibrillated microcrystalline cellulose as a filler in silicone foam: An integrated experimental and simulation investigation

Fibrillated celluloses have gained significant attention due to their exceptional mechanical properties and eco-friendly characteristics, which make them suitable for various applications. In this study, we designed a precise approach for producing highly fibrillated microcrystalline cellulose (MCC) via ball-milling treatment using four typical silane coupling agents. The empirical data demonstrate that the fibrillization of MCC and the properties of fibrillated MCC are largely affected by the size and geometry of the functional groups of the silanes. After ball-milling, most MCC displayed enhanced e-beam tolerance and thermal stability, whereas the silane loading amount, surface area, and morphology of fibrillated MCC appeared to be random, which was exemplified by the proportional and non-proportional relationship between the loading amount and surface area of methyl silane- and phenyl silane-treated MCC, respectively. Density functional theory calculations and molecular dynamics simulations were employed to obtain the intricate details. The simulation results were in agreement with the experimental results. Finally, fibrillated MCC was incorporated into silicone foams as an additive. The thermal stability of fibrillated MCC with added silicone was greatly improved, and the tensile strength of fibrillated MCC-containing silicone foam was 44.1 and 5.4 times higher than that of the neat and MCC-containing silicone foams, respectively.

Surface reconstruction of pyrite-type transition metal sulfides during oxygen evolution reaction

Reconstruction universally occurs over non-layered transition metal sulfides (TMSs) during oxygen evolution reaction (OER), leading to the formation of active species metal (oxy)hydroxide and thus significantly influences the OER performance. However, the reconstruction process and underlying mechanism quantitatively remain largely unexplored. Herein, we proposed an electrochemical reaction mechanism, namely sulfide oxidation reaction (SOR), to elucidate the reconstruction process of pyrite-type TMSs. Based on this mechanism, we evaluated the reconstruction capability of NiS2 doped with transition metals V, Cr, Mn, Fe, Co, Cu, Mo, Ru, Rh, and Ir within different doped systems. Two key descriptors were thus proposed to describe the reconstruction abilities of TMSs: USOR (the theoretical electric potential of SOR) and ΔU (the difference between the theoretical electric potential of SOR and OER), representing the initiation electric potential of reconstruction and the intrinsic reconstruction abilities of TMSs, respectively. Our finding shows that a lower USOR readily initiate reconstruction at a lower potential and a larger ΔU indicating a poorer reconstruction ability of the catalyst during OER. Furthermore, Fe-doped CoS2 was used to validate the rationality of our proposed descriptors, being consistent with the experiment findings. Our work provides a new perspective on understanding the reconstruction mechanism and quantifying the reconstruction of TMSs.

Bi-Directional H-Bonding Modulated Soft/Hard Polyethylene Glycol-Polyaniline Coated Si-Anode for High-Performance Li-Ion Batteries

Ultrahigh-capacity silicon (Si) anodes are essential for the escalating energy demands driven by the booming e-transportation and energy storage field. However, their practical applications are strictly hampered by their intrinsically low electroconductivity, sluggish Li-ion diffusion, and undesirably large volume change. Herein, a high-performance Si anode, comprised of a modulated soft/hard coating of polyethylene glycol (PEG) (as Li-ion conductor) and polyaniline (PANI) (as electron conductor) on the surface of Si nanoparticles (NPs) through H-bonding network, is introduced. In this design, the abundant ─OH groups of soft PEG allow it to uniformly cover Si NPs while the hard PANI binds to PEG through its ─N─H group, thus constructing a tight connectin between Si and PEG-PANI (PP). Consequently, the elastic PP allows Si@PP to accommodate the huge volume expansion while possessing fine electronic/ionic conductivity. Therefore, the Si@PP anode exhibits a high initial Coulombic efficiency of 90.5% and a stable capacity of 1871 mAh g-1 after 100 cycles at 1 A g-1 with a retention of 85.7%. Additionally, the Si@PP anode also demonstrates a high areal capacity of 3.01 mAh cm-2 after 100 cycles at 0.5 A g-1 . This work reveals a scalable interface design of multi-layer multifunctional coatings for high-performance electrode materials in next-generation Li-ion batteries.

Experimental and Theoretical Insights into the Effect of Dioldibenzoate Isomers on the Performance of Polypropylene Catalysts

Experimental investigations and density functional theory (DFT) calculations were carried out to study the comprehensive effect of different 3,5-heptanedioldibenzoate (HDDB) optical isomers as the internal electron donor on the catalytic performance of Ziegler-Natta catalysts. The experimental catalytic activity of HDDB has a positive correlation with the relative content of the mesomer incorporated during catalyst preparation, while the hydrogen response of HDDB displayed a negative correlation with the relative content of the mesomer. In order to apply the DFT calculation results to the macroscopic activity of the catalyst, the content of the active centers of the catalyst was analyzed. Assuming that the content of the active centers is proportional to the internal electron donor content of the catalyst, binary linear regression was carried out, which showed a good linear correlation between experimental activity data and internal electron donor content. Furthermore, the fitted activity of the single active centers aligned well with the calculated activation energies. These results revealed that the catalytic activity of polypropylene (PP) catalysts is dependent on both the active center content and the catalytic activity of an individual active center. Additionally, the lower hydrogen response of HDDB leads to a higher molecular weight of polypropylene obtained from the RS-containing catalyst compared to the SS-containing catalyst. Further study reveals that the hydrogen transfer reactions of 2,4-pentanediol dibenzoate (PDDB)/HDDB are influenced by the orientation of the methyl/ethyl groups in different isomers, which affect the activation energy differences between the hydrogen transfer reaction and the propylene insertion reaction, and finally influence the molecular weight of PP.

Synthesis and DFT calculation of microbe-supported Pd nanocomposites with oxidase-like activity for sensitive detection of nitrite

Nanozymes have emerged as the forefront of research in analytical sensing due to their promising applications. In this study, we utilized polyethyleneimine (PEI)-modified Pichia pastoris residue to synthesize microbial-based palladium nanocomposites (Pd/MMR) through simple in-situ reduction methods. The dispersed active sites of Pd nanoparticles with a size of 2.12 ± 0.49 nm that were supported by microbial biomass provided excellent oxidative enzyme-mimicking activity to Pd/MMR. The catalytic mechanism of Pd/MMR involved the combined action of 1O2, ·OH, and ·O2-, and possible reaction pathways and corresponding energy barriers were also revealed using DFT calculations. We also established a quantitative detection platform for nitrite using Pd/MMR. The platform could detect nitrite at concentrations of 10-300 μM with a detection limit of 0.27 μM, and was successfully applied to detect nitrite in real samples. These findings serve as a reference for the synthesis and application of metal nanocomposites using microorganisms.

Synthesis of anthraquinone-connected coumarin derivatives via grindstone method and their evaluation of antibacterial, antioxidant, tyrosinase inhibitory activities with molecular docking, and DFT calculation studies

Anthraquinones and coumarins have excellent pharmacological activities and are an important class of natural plant metabolites with various biological activities. In this study, anthraquinone-9,10-dione and coumarin derivatives were combined to develop a novel anthraquinone-connected coumarin-derivative sequence. The synthesised novel anthraquinone-connected coumarin derivatives (1a-t) were screened for in vitro antibacterial, antioxidant, and tyrosinase inhibitory activities. The antibacterial activities of the synthesised compounds (1a-t) were tested against both gram-positive and gram-negative bacteria. Specifically, compound 1t was more active against E. aerogenes than ciprofloxacin. With regard to antioxidant activity, compound 1o (50.68 % at 100 μg/mL) was highly active compared to the other compounds, whereas it was less active than the standard BHT (76.74 % at 100 μg/mL). In terms of compound 1r (9.31 ± 0.45 μg/mL) was highly active against tyrosinase inhibitory activity compared with kojic acid (10.42 ± 0.98 μg/mL). In the molecular docking study, compound 1r had a higher docking score (-8.8 kcal mol-1) than kojic acid (-1.7 kcal mol-1). DFT calculations were performed to determine the energy gap of highly active compound 1r (ΔE = 0.11) and weakly active compound 1a (ΔE = 0.12). In this study, we found that every molecule displayed significant antibacterial, antioxidant, and tyrosinase inhibitory properties. Based on these reports, compounds 1r and 1t may act as multi-target agents.

Efficient Electron Transfer through Interfacial Water Molecules across Two-Dimensional MoO3 for Humidity Sensing

Resistive humidity sensors are required in flexible and integrated devices. Two-dimensional MoO3 offers a large interface area, enabling the modulation of its electrical properties over a wide range. In this study, 2D MoO3 was synthesized via liquid-phase exfoliation for humidity-sensing tests. In terms of high sensitivity, negligible hysteresis, linearity, and stability, the humidity-sensing performance of MoO3 is superior to those of other materials. The sensitivity reaches 9794 Ω/RH at 25 °C. The sensing mechanism of MoO3 was investigated by using impedance spectra and voltage-current scans under different humidity levels. The results indicate that the resistance change of MoO3 due to humidity originates from the interfacial conductance. Interfacial H2O adsorption induces efficient conducting paths via hydrogen bonding, decreases the potential barrier for electron transfer, and supplies additional electron states to the valence bands. In this study, electronic humidity sensing was investigated in depth, and a new perspective was proposed for electronic humidity sensing.

Ferro/Nonferroelectric Vertical Heterostructure Superlattice as a Visible-Light-Responsive Photocatalyst: A DFT Prediction

Developing narrow-band-gap ferroelectric semiconducting photocatalysts is a promising strategy for efficient photocatalytic water splitting with high energy conversion efficiency. Within this context, six ferro/nonferroelectric vertical heterostructure superlattices (VHSs) are constructed in this work by stacking ferroelectric SiS or GeS with nonferroelectric layered organic photocatalysts (C2N, g-C3N4, and melon), layer by layer. The geometry and electronic structures of these six VHSs are systematically investigated by density functional theory calculations. Consequently, four VHSs (SiS/g-C3N4, GeS/C2N, GeS/g-C3N4, and GeS/melon) are predicted to simultaneously possess several important and highly desirable features for photocatalytic water splitting, namely excellent visible-light adsorption, remarkable spontaneous polarization (0.49-0.70 C/m2), spatial charge separation, as well as suitable band-edge positions, thus serving as potential candidates for photocatalytic water splitting to produce hydrogen. This work not only provides a new strategy to use narrow-band-gap ferroelectric semiconductors for photocatalytic water splitting but also offers inspiration for developing photocatalysts with high energy conversion efficiency.

Fluorescent Sensor Based on 1H-Pyrazolo[3,4-b]quinoline Derivative for Detecting Zn2+ Cations

The photophysical and sensory properties of the donor-acceptor pyrazoloquinoline derivative (PQPc) were investigated using absorption, steady-state, and time-resolved fluorescence measurements. The compound synthesized from commercial, readily available substrates exhibited absorptions in the UV-Vis range, with a maximum of the longwave band around 390 nm. The maximum fluorescence was around 460-480 nm, depending on the solvent. The quantum yield was between 12.87% (for n-hexane) and 0.75% (for acetonitrile) and decreased with increasing solvent polarity. The PET mechanism was implicated as the cause of fluorescence quenching. Divalent ions such as Zn2+, Pb2+, Cd2+, Ca2+, Mg2+, Co2+, Ni2+, and Cu2+ were introduced to study the fluorescent response of PQPc. A 13-times increase in fluorescence quantum yield was observed after the addition of Zn2+ ions. Detailed research was carried out for the PQPc-Zn2+ system in order to check the possibility of analytical applications of PQPc as a fluorescent sensor. A detection limit of Zn2+ was set at the value level 1.93 × 10-7 M. PQPc-Zn2+ complexes had a stoichiometry of 1:1 with a binding constant of 859 M-1. Biological studies showed that the sensor was localized in cells near the membrane and cytoplasm and may be used to detect zinc ions in eukaryotic cells.

Unexpected Promotion Effect of H2O on the Selective Catalytic Reduction of NOx with NH3 over Cu-SSZ-39 Catalysts

Water molecules commonly inhibit the selective catalytic reduction (SCR) of NOx with NH3 on most catalysts, and water resistance is a long-standing challenge for SCR technology. Herein, by combining experimental measurements and density functional theory (DFT) calculations, we found that water molecules do not inhibit and even promote the NOx conversion to some extent over the Cu-SSZ-39 zeolites, a promising SCR catalyst. Water acting as a ligand on active Cu sites and as a reactant in the SCR reaction significantly improves the O2 activation performance and reduces the overall energy barrier of the catalytic cycle. This work unveils the mechanism of the unexpected promotion effect of water on the NH3-SCR reaction over Cu-SSZ-39 and provides fundamental insight into the development of zeolite-based SCR catalysts with excellent activity and water resistance.

NiCoP cocatalyst modified g-C3N4 as ohmic junction photocatalyst for efficient degradation of tetracycline under visible light

Increasing the electron-hole recombination rate in g-C3N4 can effectively improve its photocatalytic performance. In this work, NiCoP/g-C3N4 (NCP/PCN) composites with ohmic junction were formed by embedding granular NiCoP in irregularly porous g-C3N4. There was almost no barrier between the metal and the semiconductor in ohmic junction, which made it easier for electrons to slip from PCN to NCP along the curved energy band, and NCP acted as an electron collector to rapidly capture the slipping electrons. In addition, porous g-C3N4 prepared by supramolecular self-assembly could provide a shorter diffusion path for electrons. Thus, the electron-hole was effectively separated and the photocatalytic performance was improved. The band electronic structure and existence of ohmic junction in 7-NCP/PCN composite were demonstrated by XPS, ESR and DFT calculation. Finally, a reasonable photocatalytic degradation mechanism and possible tetracycline degradation path were proposed. This work has significant potential for providing an effective method for the design of non-precious metal photocatalysts.

DFT mechanistic study of biomimetic diiron complex catalyzed dehydrogenation: Unexpected Fe(III)Fe(III)-1,1-μ-hydroperoxy active species for hydride abstraction

The diiron active site is pivotal in catalyzing transformations in both biological and chemical systems. Recently, a range of biomimetic diiron catalysts have been synthesized, drawing inspiration from the active architecture of soluble methane monooxygenase (sMMO). These catalysts have been successfully deployed for the dehydrogenation of indolines, marking a significant advancement in the field. Using density functional theory (DFT) calculations, we have identified a novel mechanistic pathway that governs the dehydrogenation of indolines catalyzed by a biomimetic diiron complex. Specifically, this reaction is facilitated by the transfer of a hybrid atom from the C1 position of the substrate to the distal oxygen atom of the Fe(III)Fe(III)-1,1-μ-hydroperoxy active species. This transfer serves as the rate-limiting step for the heterolytic cleavage of the OO bond, ultimately generating the substrate cation. The mechanism we propose aligns well with mechanistic investigations incorporating both kinetic isotope effect (KIE) measurements and evaluations of stereochemical selectivity. This research contributes to the broader scientific understanding of catalysis involving biomimetic diiron complexes and offers valuable insights into the catalytic behaviors of non-heme diiron metalloenzymes.

Remote-Controllable Interfacial Electron Tunneling at Heterogeneous Molecular Junctions via Tip-Induced Optoelectrical Engineering

Molecular electronics enables functional electronic behavior via single molecules or molecular self-assembled monolayers, providing versatile opportunities for hybrid molecular-scale electronic devices. Although various molecular junction structures are constructed to investigate charge transfer dynamics, significant challenges remain in terms of interfacial charging effects and far-field background signals, which dominantly block the optoelectrical observation of interfacial charge transfer dynamics. Here, tip-induced optoelectrical engineering is presented that synergistically correlates photo-induced force microscopy and Kelvin probe force microscopy to remotely control and probe the interfacial charge transfer dynamics with sub-10 nm spatial resolution. Based on this approach, the optoelectrical origin of metal-molecule interfaces is clearly revealed by the nanoscale heterogeneity of the tip-sample interaction and optoelectrical reactivity, which theoretically aligned with density functional theory calculations. For a practical device-scale demonstration of tip-induced optoelectrical engineering, interfacial tunneling is remotely controlled at a 4-inch wafer-scale metal-insulator-metal capacitor, facilitating a 5.211-fold current amplification with the tip-induced electrical field. In conclusion, tip-induced optoelectrical engineering provides a novel strategy to comprehensively understand interfacial charge transfer dynamics and a non-destructive tunneling control platform that enables real-time and real-space investigation of ultrathin hybrid molecular systems.

Preliminary studies of XANES and DFT calculation of Ru extraction by imino-diacetamide and related compounds

We connected three research fields on Ru extraction, XANES, and DFT calculation and elucidate the sequence of distribution ratio (D) and their reactions. The magnitude order of the distribution ratio, D(Ru), from acids, HCl > H2SO4 > HNO3 > HClO4, by IDOA indicates to extract readily the stable Ru-Cl ions. The XANES signals, which suggests the electrical charge of Ru(III) extracted into the organic phase, supports the ion-pairing extraction of the anionic Ru-Cl complex with an extractant protonated. Ru(III) in other acids might be extracted by solvation of extractant, thus ion-pair extraction is stronger than solvation in Ru extraction. According to the D(Ru), the same extractant trend, NTAamide > MIDOA > IDOA, as the energy gap of HOMO and LUMO by DFT calculation is found, which suggests that DFT calculation can give the relative magnitude of each D(M) value when extractant and metal in an extraction are determined.

Synthesis and Evaluation of Antimicrobial Activity of the Rearranged Abietane Prattinin A and Its Synthetic Derivatives

Synthesis of the natural product prattinin A and some new derivatives has been achieved using abietic acid. The final products and a selection of intermediates were evaluated for their antibacterial activity against three human pathogenic bacteria: E. coli, P. aeruginosa, and S. aureus. The results showed that the antibacterial activity varies depending on the chemical structure of the compounds. Notably, compound 27 exhibited the most potent activity against E. coli and P. aeruginosa, with a minimal inhibitory concentration (MIC) of 11.7 µg/mL, comparable to that of the standard antibiotic ciprofloxacin, and strong activity against S. aureus, with an MIC of 23.4 µg/mL. Furthermore, we assessed the stability of these derivative compounds as potential antimicrobial agents and determined their interactions with the crystal structure of the protein receptor mutant TEM-12 from E. coli (pdb:1ESU) using molecular docking via UCSF Chimera software 1.17.3. The results suggest that 27 has potential as a natural antibiotic agent.

Catalytic Ozonation of Air toward Direct Nitric Acid Production Using Hierarchical Co3O4 with a Tunable Microstructure

The nitrogen oxidation reaction (NOR) to form nitric acid by applying natural air and H2O under ambient conditions is a sustainable approach to achieving efficient and selective N2 fixation for industrial applications. In this study, four kinds of Co3O4 catalysts with a controllable microstructure were prepared to catalyze the direct NOR of N2 in the air. At the same time, the reaction mechanism of the conversion of N2 to nitric acid under catalytic ozonation was explored through experimental research and density functional theory (DFT) calculation. The results showed that the prepared porous nanosheets self-assembled into microflower-structured samples. The HCOF showed extraordinary catalytic performance for direct NOR to produce a high concentration of nitric acid. The maximum rate of nitric acid formation could be as high as 6.67 mmol/(h·gcat), which was higher than those of most reported photocatalytic or electrocatalytic N2 fixation processes for direct NOR to produce NO3-. Furthermore, the 15N isotopic-labeling experiment confirmed that the produced NO3- originated from N2 in the air by the direct NOR process. In the direct NOR mechanism, inert N2 molecules were captured at the Co3+ active sites by the acceptance-donation electron conduction mode, and the oxygen vacancies boosted the chemical adsorption of N2 molecules and greatly reduced the activation energy barrier of N2 molecules. The active free radicals •OH and •O2- generated by the decomposition of O3 molecules oxidized N2 to the intermediate *NO, which was the rate-determining step, and it was then absorbed by water to form nitric acid. The air catalytic ozonation method in this study was proposed as a facile pathway for efficient nitrogen fixation. This research provides a new method for environmental protection and efficient production of nitric acid at distributed sources.

Self-Assembled Nanotubes Based on Chiral H8-BINOL Modified with 1,2,3-Triazole to Recognize Bi3+ Efficiently by ICT Mechanism

A novel fluorescent "off" probe R-β-D-1 containing a 1,2,3-triazole moiety was obtained by the Click reaction with azidoglucose using H8-BINOL as a substrate, and the structure was characterized by 1H NMR and 13C NMR and ESI-MS analysis. The fluorescence properties of R-β-D-1 in methanol were investigated, and it was found that R-β-D-1 could be selectively fluorescently quenched by Bi3+ in the recognition of 19 metal ions and basic cations. The recognition process of Bi3+ by R-β-D-1 was also investigated by fluorescence spectroscopy, SEM, AFM, etc. The complex pattern of R-β-D-1 with Bi3+ was determined by Job's curve as 1 + 1, and the binding constant Ka of R-β-D-1 and Bi3+ was valued by the Benesi-Hildebrand equation as 1.01 × 104 M-1, indicating that the binding force of R-β-D-1 and Bi3+ was medium. The lowest detection limit (LOD) of the self-assembled H8-BINOL derivative for Bi3+ was up to 0.065 µM. The mechanism for the recognition of Bi3+ by the sensor R-β-D-1 may be the intramolecular charge transfer effect (ICT), which was attributed to the fact that the N-3 of the triazole readily serves as an electron acceptor while the incorporation of Bi3+ serves as an electron donor, and the two readily undergo coordination leading to the quenching of fluorescence. The recognition mechanism and recognition site could be verified by DFT calculation and CDD (Charge Density Difference).

Enhanced photolysis of tetracycline by Zn(II): Role of complexation

Zn(II) is a necessary additive during antibiotic production and aquaculture, leading to the coexistence of Zn(II) and antibiotics in aquatic environment, especially in receiving waters of pharmaceutical and aquaculture wastewater. However, the roles of Zn(II) in the photochemical behavior of antibiotics are still not clear, which limits the understanding of the fate of antibiotic in nature. In this study, tetracycline (TC) was selected as typical antibiotic to evaluate the effect of Zn(II) on antibiotic photolysis. The removal of TC was accelerated by 22.75 % with TC:Zn(II) molar ratio at 1:5. The mechanism of Zn(II)-induced TC photolysis was explored via reactive oxygen species (ROS) analysis and density functional theory (DFT) calculation for the first time. Zn(II) could enhance the formation of TC excited states and further produce more singlet oxygen (12.54 % higher than control group) to promote indirect photolysis. Besides, Zn(II) could react with TC via complexation, and the complex was more vulnerable to attack by reactive oxygen species due to more active sites. Furthermore, the structure and toxicity of intermediates were identified with mass spectrometer, T.E.S.T. and ECOSAR software. Zn(II) hardly changed the degradation path of TC, and TC was mainly degraded via ring opening, demethylation, deamidation, and hydrogen abstraction with more toxic intermediates than the parent molecule. This work is significant to better understand the environmental fate of antibiotics, and also provides new insight into wastewater treatment in the pharmaceutical and aquaculture industry.

A unique N-heterocyclic oligo(N,O-donor) salamo-Ni(II)-based probe for highly selective fluorescence detection of Cr2O72

A unique fluorescent probe Ni-DAS was developed by a nitrogenous heterocyclic oligo(N,O-donor) salamo-based compound DAS. DAS exhibits AIE and ESIPT effects which are extremely infrequent in salamo-based multi-oxime compounds. In addition, Ni-DAS can be used as a fluorescent probe with high selectivity and sensitivity to recognize Cr2O72- in DMF with 80 % water content, which enhances the value of the probe for application in real environments, and outperforms most similar molecular fluorescence probes. The probe Ni-DAS can recognize Cr2O72- by oxidative hydrolysis of C = N bonds, which promotes further research on theory of C = N bond hydrolysis, and the binding ratio and recognition mechanism were verified and supported by relevant theoretical calculations (DFT & MESP). The experiments showed that the probe Ni-DAS can be used for ion detection in real environments. It provides a new strategy for the oxidative hydrolysis of C = N bond and the structure of salamo-based compounds with AIE nature, and offers new ideas for study ion recognition and acidity detection.

Synergistic Effect of Ion Doping and Type-II Heterojunction Construction and Ciprofloxacin Degradation by MIL-68(In,Bi)-NH2@BiOBr under Visible Light

Heterojunction structure and ion doping techniques are viable tactics in facilitating the generation and separation of photogenerated electrons and holes in photocatalysis. In the current study, a novel Bi ion-doped MIL-68(In,Bi)-NH2@BiOBr (MIBN@BOB) type-II heterojunction was first synthesized in a one-step solvothermal reaction. Doping of Bi ions not only broadened the light-sensing range but also provided reliable anchor sites for the in situ growth of BiOBr. Meanwhile, the heterostructure supplied new channels for photogenerated carriers, accelerating the transfer and inhibiting the recombination of photogenerated electron-hole. The obtained MIBN@BOB exhibited enhanced photocatalytic performance (91.1%) than MIL-68(In)-NH2 (40.8%) and BiOBr (57.5%) in ciprofloxacin (CIP) degradation under visible light, with excellent reusability. Photocatalysts were characterized in detail, and a series of photoelectrochemical tests were utilized to analyze the photoelectric properties. MIBN@BOB were deduced to conform the electron conduction mechanism of conventional type-II heterojunctions. More importantly, based on the above experiments and density functional theory (DFT) calculation, BiOBr-Bi in MIBN@BOB can serve as the major active sites of CIP enrichment, and •O2- and 1O2 generated at the BiOBr interface can react with the adsorbed CIP directly. Lastly, the possible degradation products and pathways of CIP were analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). This study provides a reference for the construction of ion-doping-modified metal-organic framework (MOF)-based heterojunction photocatalysts and their application in antibiotic removal.

Dopant-Induced Charge Redistribution on the 3D Sponge-like Hierarchical Structure of Quaternary Metal Phosphides Nanosheet Arrays Derived from Metal-Organic Frameworks for Natural Seawater Splitting

Dopant-induced electron redistribution on transition metal-based materials has long been considered an emerging new electrocatalyst that is expected to replace noble-metal-based electrocatalysts in natural seawater electrolysis; however, their practical applications remain extremely daunting due to their sluggish kinetics in natural seawater. In this work, we developed a facile strategy to synthesize the 3D sponge-like hierarchical structure of Ru-doped NiCoFeP nanosheet arrays derived from metal-organic frameworks with remarkable hydrogen evolution reaction (HER) performance in natural seawater. Based on experimental results and density functional theory calculations, Ru-doping-induced charge redistribution on the surface of metal active sites has been found, which can significantly enhance the HER activity. As a result, the 3D sponge-like hierarchical structure of Ru-NiCoFeP nanosheet arrays achieves low overpotentials of 52, 149, and 216 mV at 10, 100, and 500 mA cm-2 in freshwater alkaline, respectively. Notably, the electrocatalytic activity of the Ru-NiCoFeP electrocatalyst in simulated alkaline seawater and natural alkaline seawater is nearly the same as that in freshwater alkaline. This electrocatalyst exhibits superior catalytic properties with outstanding stability under a high current density of 85 mA cm-2 for more than 100 h in natural seawater, which outperforms state-of-the-art 20% Pt/C at high current density. Our work provides valuable guidelines for developing a low-cost and high-efficiency electrocatalyst for natural seawater splitting.

Arrayed Pt Single Atoms via Phosphotungstic Acids Intercalated in Silicate Nanochannels for Efficient Hydrogen Evolution Reactions

Single-atom catalysts, known for their high activity, have garnered significant interest. Currently, single-atom catalysts were prepared mainly on 2D substrates with random distribution. Here, we report a strategy for preparing arrayed single Pt (Pt1) atoms, which are templated through coordination with phosphotungstic acids (PTA) intercalated inside hexagonally packed silicate nanochannels for a high single Pt-atom loading of ca. 3.0 wt %. X-ray absorption spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy, in conjunction with the density-functional theory calculation, collectively indicate that the Pt single atoms are stabilized via a four-oxygen coordination on the PTA within the nanochannels' inner walls. The critical reduction in the Pt-adsorption energy to nearly the cohesive energy of Pt clustering is attributed to the interaction between PTA and the silicate substrate. Consequently, the transition from single-atom dispersion to clustering of Pt atoms can be controlled by adjusting the number density of PTA intercalated within the silicate nanochannels, specifically when the number ratio of Pt atoms to PTA changes from 3.7 to 18. The 3D organized Pt1-PTA pairs, facilitated by the arrayed silicate nanochannels, demonstrate high and stable efficiency with a hydrogen production rate of ca. 300 mmol/h/gPt─approximately twice that of the best-reported Pt efficiency in polyoxometalate-based photocatalytic systems.

Catalytic activation of percarbonate with synthesized carrollite for efficient decomposition of bisphenol S: Performance, degradation mechanism and toxicity assessment

This study demonstrates the novel application of carrollite (CuCo2S4) for the activation of sodium percarbonate (SPC) towards bisphenol S (BPS) degradation. The effect of several crucial factors like BPS concentration, CuCo2S4 dosage, SPC concentration, reaction temperature, water matrices, inorganic anions, and pH value were investigated. Experimental results demonstrated that BPS could be efficiently degraded by CuCo2S4-activated SPC system (88.52% at pH = 6.9). The mechanism of BPS degradation by CuCo2S4-activated SPC system was uncovered by quenching and electron spin resonance experiments, discovering that a multiple reactive oxygen species process was involved in BPS degradation by hydroxyl radical (•OH), superoxide radical (•O2-), singlet oxygen superoxide (1O2) and carbonate radical (•CO3-). Furthermore, the S(-II) species facilitated rapid redox cycles between Cu(I)/Cu(II) and Co(II)/Co(III). •CO3- was found to not only directly react with BPS molecules, but also act as a bridge to promote •O2- and 1O2 generation, thereby accelerating BPS degradation. Finally, the combination of UHPLC/Q-TOF-MS test with density functional theory (DFT) method was employed to detect major degradation intermediates and thereby elucidate possible reaction pathways of BPS degradation. This study provides a novel strategy by integrating transition metal sulfides with percarbonate for the elimination of organic pollutants in water.

Effects of charge-assisted hydrogen bond on sorption and co-sorption of pharmaceutical contaminants on carbonaceous materials: Spectroscopic and theoretical studies

Charge-assisted hydrogen bond (CAHB) is a key mechanism that affects the environmental behavior of pharmaceutical pollutants (PCs). However, the strength and stability of various CAHBs, and their effects on the co-sorption behavior of PCs are still unclear. Herein, DFT calculation with different solvent models including two implicit solvent model (PCM and SMD), and one explicit solvent model (ESM) were applied in this study, to investigate the effects of different CAHBs on the sorption and co-sorption behavior of four PCs (e.g., clofibric acid, p-aminobenzoic acid, acetaminophen, and sulfamerazine) on three model carbonaceous materials. First, the appearance of new peaks in the very low field of 1H NMR, and the blue shift of OH and NH2 peaks in FTIR indicated that CAHBs were indeed formed between PCs and carbonaceous materials. Next, according to the principal component analysis and correlation analysis of parameters (e.g., ΔEads, bond length, bond angle, Egap, and ΔG) of these CAHBs calculated by the DFT with different solvent models, the results showed that SMD is the optimal model for calculating the strength and stability of CAHBs by DFT, and the strength and stability of CAHBs formed between PCs and carbonaceous materials in this study were in the order of homonuclear [O⋯H⋯O]- CAHB > heteronuclear [O⋯HN]-/[N⋯HO]+ type of CAHB > homonuclear [N⋯H⋯N]+. Also, the co-sorption behavior of different PCs co-existing in binary systems further confirmed that, all above types of CAHBs formed between PCs and carbonaceous materials can produce obvious competition effect on the co-existing PCs that only OHB formed between them. This study not only reveals the environmental behavior of co-existing PCs, but also provides a theoretical basis for the design of obligate sorption materials for PCs in the natural environment.