From molecules to solids with the DMol3 approach

Machine-learning for discovery of descriptors for gas-sensing: A case study of doped metal oxides

Conventionally, gas sensors are studied based on functional materials, case by case, using experimental methods. In this study, 872 datasets with 34 features of doped oxides, extracted from the literature, were used to analyze the key features of gas-sensing reactions and understand gas-sensing mechanisms from a global perspective using a genetic algorithm-optimized artificial neural network. Shapley additive explanations were employed to determine the importance and relationships of the features. Based on the physical meaning of the important features, the characteristics of doped oxides and gas molecules are described in terms of sensitivity, measurement range, and selectivity. The reactivity of gas molecules has a strong impact on the sensitivity of doped oxides; sensors with low sensitivity usually have a wide measuring range. The selectivity of doped oxides depends on a suitable doping ratio, oxygen configurations, and the electrophilicity of gas molecules. The best characteristics of the doped oxides in gas sensing were predicted using a generative adversarial net. This study contributes toward improving gas-sensing materials.

Engineering nitrogen-doped carbon quantum dots: Nitrogen content-controlled dual-phase emission behavior

Nitrogen doping is a widely used method for enhancing the performance of carbon quantum dots (CQD). However, the precise relationship between nitrogen content and emission spectra remains unclear when preparing high-performance nitrogen-doped CQD (N-CQD). This study systematically investigates the effects of nitrogen content on the crystalline structure, optical properties, and electronic band structure of N-CQD. Citric acid was used as the carbon source, and ethylenediamine monohydrate was used as the nitrogen source, with their ratio controlled to hydrothermal synthesized N-CQD with N/C ratios ranging from 0 to 0.4. Notably, when the N/C ratio increases from 0 to 0.2, the N-CQD exhibits redshifted emission with excitation dependence. However, when the N/C ratio rises from 0.2 to 0.4, the N-CQD shows blueshifted emission with excitation-independence. We define it as the dual-phase emission behavior of N-CQD attributed to the transition of doping sites from graphitic nitrogen to pyridine nitrogen with increased nitrogen content. DFT calculations indicate that different doping sites influence electron transfer in N-CQD, resulting in distinct optical behaviors. Importantly, this work comprehensively explains the relationship between nitrogen content and the emission behavior of N-CQD for the first time, providing crucial insights for refining the theoretical framework of N-CQD.

N, P-doped graphite/LiMn2O4 hybrid electrode for high-performance all-climate dual-ion batteries

Conventional lithium-ion batteries (LIBs) are nearing their theoretical capacity limit, and there is an urgent need to develop energy storage devices with higher energy densities and cycling stabilities. In this work, a hybrid electrode design, which combines the traditional "rocking chair" mechanism and "anion intercalation" mechanism to improve energy density is reported. The hybrid electrode is composed of LiMn2O4 and N,P-doped graphite (NPG) to use both anion and cation storage mechanisms. This design enhances the electrochemical potential windows and the energy density of the fabricated cell. Electrochemical results show that the fabricated cell not only shows a 44.1 % higher capacity than conventional LIBs. It displays a stable cycle life across a wide climate temperature range from - 20 to 25 °C, with a capacity retention rate of 86 % after 600 cycles at 100 mA g-1. This study demonstrates the critical role of doping graphite with N and P to improve the electrochemical performance of graphite in deep charge/discharge, providing a valuable strategy for developing cathode materials in dual-ion batteries.

New strategy for the utilization of invasive species: A tert-butylhydroquinone electrochemical platform based on Solidago canadensis L

Tert-butylhydroquinone (TBHQ) is a widely used synthetic phenolic antioxidant found in edible oils and other fried foods. Nevertheless, the excess use of TBHQ can reduce food quality and impact public health. In this paper, we reported the synthesis of a nanocomposite consisting of carbon and nitrogen co-doped nickel oxide (NiO-N/C-700), which was used to modify a pencil graphite electrode for the sensitive detection of TBHQ. The carbon source was biochar derived from invasive species Solidago canadensis L., combined with inexpensive pencil graphite, which reduced overall cost. The as-prepared TBHQ electrochemical sensor exhibited a linear range of 0.02-200 μM, a limit of detection of 5.53 nM. In particular, this sensor can be applied for the quantitative detection of TBHQ in edible oil, fried food and crisps, achieving a satisfactory recovery rate of 99.30 %-106.40 %, promoting TBHQ detection in actual food samples.

Solution processable triarylamine-based polyamide for electrochromic supercapacitors and smart displays with energy reuse

Electrochromic (EC) materials based on ion insertion/desertion mechanisms provide a possibility for energy storage. Solution-processable energy storage EC polyamides have great potential for use in smart displays and EC supercapacitors. A suitable monomer structure design is particularly important for enhancing the electrochemical properties of polyamides. The symmetrical donor-acceptor-donor structure triarylamine (TAA) diamine monomer was prepared by the Ullmann reaction, and the corresponding polyamide (named BDPA-CA) was prepared by polycondensation reaction. The propeller-shaped skeleton of the TAA unit effectively increases the internal volume and endows the BDPA-CA with the property of solution processing. The introduction of electron-withdrawing benzothiadiazole groups into the main chain enhances the optical contrast of BDPA-CA during electrochemical oxidation. Moreover, the energy storage mechanism of BDPA-CA is elucidated via density functional theory calculations. The exposed sulfur (S) and oxygen (O) atoms in BDPA-CA can serve as active sites for lithium ion (Li+) binding, and the nitrogen (N) atom at the center of the TAA moiety is a perchlorate ion (ClO4-) binding active site, which suggests that the full interaction of the dual active sites can increase the capacitance value of the BDPA-CA film electrodes.

Synthesis of honeycomb-like citric acid-crosslinked chitosan hydrogel beads (cCHBs): Insight into structural characteristics of Cu(II)-loaded cCHBs (cCHBs-Cu(II))

To date, it has been regarded as one of the most challenging issues to construct novel adsorbents possessing excellent adsorption performance toward heavy metals including copper ions (Cu(II)). Especially, it is controversy about the structural characteristics of chitosan-based adsorbents adsorbed with Cu(II) ions, which could function as new adsorbents. In this study, we adopt a freeze-drying process to synthesize honeycomb-like chitosan hydrogel beads crosslinked with citric acid (cCHBs), further characterize the microstructures of cCHBs and eventually reveal the thermodynamics equations for the removal of target Cu(II). The results show that (1) the tricarboxylic groups within citric acid could prompt to construct long-range ordered channels of cCHBs under a freeze-drying process; (2) the maximum adsorption capacity of cCHBs for Cu(II) was 195.3 mg g-1 calculated by a Langmuir model; (3) the adsorption process of Cu(II) onto cCHBs was a spontaneous, endothermic, and entropy-increasing process. Moreover, the structural characteristics for honeycomb-like cCHBs adsorbed with Cu(II) (cCHBs-Cu(II)) as new adsorbents have been revealed with the adsorption of phosphate anions, which were further simulated with density functional theory (DFT). Accordingly, the superior adsorption performance of cCHBs and cCHBs-Cu(II) sheds light on a significant candidate for selective separation of a series of oxyanions.

Construction of Se-doped carbon encapsulated Cu2Se yolk-shell structure for long-life rechargeable aluminum batteries

Rechargeable aluminum batteries (RABs) are promising alternatives to lithium-ion batteries in large-scale energy storage applications owing to the abundance of their raw materials and high safety. However, achieving high energy density and long cycling life simultaneously holds great challenges for RABs, especially for high capacity transition metal selenide (TMS)-based positive materials suffering from structural collapse and dissolution in acidic ionic liquid electrolyte. Herein, Se-doped carbon encapsulated Cu2Se with yolk-shell structure (YS/Se-C@Cu2Se) is rationally constructed to address such issues. Electrochemical and spectroscopic analyses as well as density functional theory calculations show that the highly conductive Se-C shell enhances the electrochemical reaction kinetics of the electrode and provides strong adsorption for the soluble Cu and Se species. Benefiting from these merits, the optimal YS/Se-C@Cu2Se cathode manifests a high specific capacity of 1024.2 mAh/g at 0.2 A/g, a superior rate capability of 240.5 mAh/g at 3.2 A/g, and a long-term cycling stability over 2500 cycles. This work offers a feasible approach to the design and construction of low-cost and efficient TMS-based positive materials for realizing practically usable RABs.

Experimental and theoretical approaches to unveil the interaction mechanisms of carbon dots with 4-nitrophenol

Developing a non-toxic, cost-effective, biocompatible, selective, and sensitive optical sensor for the optical detection of 4-nitrophenol (4-NP) has been challenging yet significant. Among carbon-based materials, the selectivity of carbon dots toward 4-NP is a key area of research, and a comprehensive understanding is crucial to broaden its practical application. Our unique contribution to this field involves synthesizing and testing different N-doped carbon dots (CDs) for selective 4-NP detection through absorbance and photoluminescence. We have also theoretically provided the interaction mechanism between 4-NP and N-doped CDs (H-NCDs). The optimized hydrothermally synthesized nitrogen-doped CDs demonstrate excellent specificity towards 4-NP through simultaneous quenching of the PL (98 %) and redshift of the signal (34 nm) in an aqueous medium. The density functional theory (DFT) model that was performed to understand the electronic structure properties behind the interaction of 4-NP and CD could be a predictive tool for developing CD-based materials to enhance 4-NP capture. Our study provides a mechanistic understanding of the analyte-specific CD design. It offers promising implications for the practical application of our findings, thereby contributing a unique perspective to the field and benefiting various industries and environmental monitoring efforts, sparking optimism for the future.

Mechanisms for Modifying the Electronic and Spatial Distribution of the Single-Atom Ni/CeO2 Surface to Enhance CO-SCR Reactivity: Density Functional Theory Study

Modulating the intrinsic activity of heterogeneous catalysts at the atomic level is an effective strategy to improve the low-temperature CO-SCR (selective catalytic reduction) reaction activity and N2 selectivity, but it remains challenging by the experiment. In this paper, a single-atom-loaded surface generation strategy is developed to construct single-atom catalysts by density functional theory analysis, which will effectively reduce the reaction energy barriers in CO-SCR reaction. Specifically, the reaction of NO reduction by CO before and after Ni adsorption was thoroughly investigated and the reactivity was evaluated by using the CeO2 (1 1 1) surface as a carrier, with the application of density functional theory, electronic structure analysis, and transition state theory. The loading of Ni increases the energy barrier for the generation of N2O on the CeO2 (1 1 1) surface by 1.498 eV and decreases the energy barrier for the generation of N2 by 1.864 eV. This indicates that the adsorption of Ni inhibits the generation of N2O and promotes the generation of N2. After thermodynamics and kinetics analysis, the pathway of CeO2 (1 1 1)-Ot-Ni via O atoms filling O vacancies to generate N2 is a spontaneous unidirectional reaction when no nonvolumetric work is done at constant temperature and pressure. Theoretical calculations show that the modification of isolated Ni atoms on CeO2 induces electronic coupling and redistribution, which leads to the activation of neighboring O sites around Ni atoms. This study provides the strategy mechanism to enhance the activity and N2 selectivity of the low-temperature CO-SCR reaction at the atomic level and provides theoretical guidance for the theory of novel catalysts for synergistic removal of NO and CO.

Structural Changes at the Zinc Active Site of ACE2 on Binding the SARS-CoV-2 Spike Protein Receptor Binding Domain

The causative agent of Covid-19 is the SARS-CoV-2 virus. Initiation of cell entry by SARS-CoV-2 is critically dependent upon binding of the SARS-CoV-2 spike protein to angiotensin-converting enzyme 2 (ACE2, EC 3.4.17.23). The mechanism of binding of the SARS-CoV-2 spike receptor binding domain to ACE2 is among the most intensively studied infection mechanisms of any pathogen, including a very large number of structural studies. ACE2 is a membrane-associated zinc carboxypeptidase, comprising three domains, the protease domain, a neck domain, and a membrane-spanning α-helical domain. In addition to its role as a carboxypeptidase, ACE2 is also a chaperone for a Na+-amino acid cotransporter called B0AT1, and in the presence of B0AT1, full-length ACE2 forms dimers. Most studies to date related to Covid-19 have employed just the ACE2 protease domain and have neglected any possible roles of the Zn2+-containing ACE2 active site. We show here that ACE2, including the neck domain in addition to the protease domain (and in the absence of B0AT1), is dimeric and shows distinctive allostery in its catalytic activity. In contrast, the intensively studied protease domain is monomeric and shows no allostery. Binding of the spike receptor binding domain (RBD) to dimeric ACE2 eliminates its allostery. X-ray absorption spectroscopy of Zn2+ ACE2 shows distinctive changes in the active site structure upon binding of spike RBD but only in the dimeric form. Taken together, our results indicate that the Zn2+-containing active site exhibits a notable level of flexibility and that the dimeric form of ACE2, including both protease and neck domains, likely presents a superior model for the study of ACE2-spike interactions than the monomeric ACE2.

AtomDB: A Python Library and Database for Atomic and Promolecular Properties

AtomDB is a free and open-source Python library for accessing and manipulating neutral and charged atomic species and their promolecular properties. It serves as a computational toolset, operating on an accompanying "extended periodic table" database, with experimental and computational data covering atomic species with a wide range of charges and multiplicities. AtomDB includes facilities for computing promolecules: local promolecular properties, constructed from the corresponding atomic densities, and scalar promolecular properties, computed from the corresponding scalar atomic properties, both taking into account whether properties are extensive or intensive. AtomDB is designed to be easy to use, extend, and maintain: it follows best practices for modern software development, including comprehensive documentation, extensive testing, continuous integration/delivery protocols, and package management. This article is the official release note for the AtomDB library.

Exploring interfacial electrocatalysis for iodine redox conversion in zinc-iodine battery

The challenges posed by the non-conductive nature of iodine, coupled with the easy formation of soluble polyiodides in water, impede its integration with zinc for the development of advanced rechargeable batteries. Here we demonstrate the in-situ loading of molybdenum carbide nanoclusters (MoC) and zinc single atoms (Zn-SA) into porous carbon fibers to invoke electrocatalytic conversion of iodine at the interface. The electronic interactions between MoC and Zn-SA lead to an upshift in the d-band center of Mo relative to the Fermi level, thus promoting the interfacial interactions with iodine species to suppress shuttle effects. Notably, the optimal charge delocalization, induced by d-p orbital hybridization between molybdenum and iodine, also lowers the redox energy barrier to promote the interfacial conversion. With interfacial electrocatalysis minimizing polyiodide intermediates via a favorable redox conversion pathway, zinc-iodine batteries therefore demonstrate a large specific capacity of 230.6 mAh g-1 and the good capacity retention for 20,000 cycles.

Regulation of Two-Component Nanostructures at the Liquid-Solid Interface: Role of Pyridine Derivatives and Coronene

We investigate the self-assembly behaviors of the tetracarboxylic acid molecule (H4IMD), which contains an imidazole moiety, and explore the regulation by pyridine derivatives with varying backbones and the guest molecule coronene (COR). Two H4IMD molecules are linked through N-H···O hydrogen bonds to form a dimer, which spontaneously self-assembles into a grid structure via O-H···O hydrogen bonds. The addition of linear pyridine derivatives (BP and Bispy) can break some of the O-H···O hydrogen bonds, allowing these pyridine molecules to insert between the dimer columns. In contrast, the tripyridine derivative (TPYB) disrupts the original dimer structures, resulting in a completely altered nanostructure. Moreover, the H4IMD self-assembled structure can be regulated into a rhombus network by the coadsorption of COR molecules. Combining scanning tunneling microscopy and density functional theory calculations, this study elucidates the diverse structural variations and the underlying mechanisms, which provide new insights into molecular coassembly.

Multienzyme-Activity Sulfur Quantum Dot Nanozyme-Mediated Cascade Reactions in Whole-Stage Symptomatic Therapy of Infected Bone Defects

Integrating the therapeutic efficacy of early bacterial clearance, midstage inflammatory remission, and late-stage effective tissue healing is considered a pivotal challenge in symptomatic treatment of infected bone defects (IBDs). Herein, a microenvironment-adaptive nanoplatform based on a sulfur quantum dot (SQD) nanozyme was proposed for whole-stage symptomatic therapy of IBDs by mediating the sequence of enzyme cascade reactions. The SQD nanozyme prepared by a size-engineering modification strategy exhibits enhanced multienzyme activity compared to conventional micrometer- and nanometer-sized sulfur particles. In the early stages of bacterial infection, the SQD nanozyme self-activates superoxide dismutase-peroxidase activity, resulting in the production of reactive oxygen species (ROS) that effectively eliminate bacteria. After disinfection, the SQD nanozyme self-switched to superoxide dismutase-catalase mimetic behavior and eliminated excess ROS, efficiently promoting macrophage polarization to an anti-inflammatory phenotype in the midinflammatory microenvironment. Importantly, SQD nanozyme-mediated M2 macrophage polarization significantly improved the damaged bone immune microenvironment, accelerating bone repair at late-stage tissue healing. Therefore, this strategy offers a promising and viable approach for the treatment of infectious tissue healing by developing multienzyme-activity nanozymes that respond intelligently to the microenvironment at different stages, effectively fighting bacteria, reducing inflammation, and promoting tissue regeneration for whole-stage symptomatic therapy.

PyPWDFT: A Lightweight Python Software for Single-Node 10K Atom Plane-Wave Density Functional Theory Calculations

PyPWDFT is a Python software designed for performing plane-wave density functional theory (DFT) calculations. It can perform large-scale DFT calculations using only a single process on a single node, including local density functional for 10,000 atoms and nonlocal hybrid functional for 4096 atoms. Our benchmark test results demonstrate that PyPWDFT achieves performance comparable to that of Fortran/C++ codes, despite being developed in a native Python environment. In addition, it requires only NumPy, SciPy, and CuPy, enabling CPU-GPU heterogeneous computing, achieving a two-order-of-magnitude speedup compared to single-threaded CPU execution. Due to its excellent cross-platform compatibility, medium-scale DFT calculations can be performed through a graphical user interface on personal computers and Windows systems using consumer-grade GPUs, such as the NVIDIA GeForce RTX 4090. The computational efficiency is comparable to that of professional-grade GPUs such as the NVIDIA V100. The efficient performance, scalability to handle large-scale systems, high numerical accuracy, and different interfaces for molecular dynamics collectively underscore the considerable potential of PyPWDFT to develop into versatile DFT software.

"Bifunctional Strontium-Iron Doped Neodymium Cobaltite: A Promising Electrocatalyst for Intermediate Temperature Solid Oxide Fuel Cells and CO2 Electrolyzer"

A novel intermediate temperature solid oxide fuel cell cathode, Nd₀.₆₇Sr₀.₃₃Co₀.₈Fe₀.₂O₃- δ (NSCF), synthesized via auto-combustion, exhibits exceptional mixed ionic-electronic conducting properties with a cubic perovskite structure. At 800 °C, NSCF demonstrates high electrical (1003 S cm-1) and ionic (1.676 × 10⁻2 S cm-1) conductivities, with activation energies of 0.0335 and 0.481 eV, respectively. Electronic analysis confirms its metallic nature, while the calculated oxygen migration energy (0.455 eV) correlates with experimental ionic conduction activation energy. The negative bulk oxygen vacancy formation energy (-38.70 kcal mol-1) indicates efficient oxygen reduction reaction and CO₂ electrolysis kinetics. Electrical conductivity relaxation shows non-debye behavior, with Dchem of 5 × 10⁻⁴ cm2 s-1 and Kex of 6.450 × 10⁻⁴ cm -1s at 800 °C. NSCF exhibits low interfacial polarization resistance (0.05 Ω cm2) and area-specific resistance (0.025 Ω cm2), further reducing to 0.014 Ω cm2 with an NSCF-GDC Gadolinium doped ceria interlayer. An anode-supported cell achieves peak power densities of 2.27, 1.52, and 0.86 W cm- 2 at 800, 750, and 700 °C, respectively. In SOEC mode, NSCF demonstrates excellent CO₂ reduction capability of constant current density of -1.1 A cm- 2 with stable 55-h performance, which establishes its potential both as IT-SOFC cathode and CO2 electrolysis catalysts.

Boosted chlorate hydrogenation reduction via continuous atomic hydrogen

Chlorate (ClO3-) is a common toxic oxyanion pollutant from various industrial processes, and hydrogenation reduction of ClO3- by atomic hydrogen (H*) is a promising and effective method. Therefore, more efforts are needed to rationalize the design of catalytic active sites for H2 activation to boost ClO3- hydrogenation reduction. In this work, superior H2 activating capabilities were achieved for efficient ClO3- reduction on a porous graphene-based bimetallic catalyst (RuPd/PG). Edge sites and porosity structures on porous graphene promote the anchoring and confinement of Ru and Pd NPs (Nanoparticles), forming abundant Pd-Ru bonding interfaces and highly dispersed NPs. Based on DFT analysis, the ample Pd-Ru interfaces and highly dispersed Ru NPs are the main active sites, simultaneously boosting H* generation and reactant activation for rapid ClO3- reduction. The defective layer of Ru NPs on the Pd surface provides intermediates with accessibility to the inner Pd NPs, thereby avoiding ClO3- regeneration on Ru. Therefore, ClO3- hydrogenation reduction was significantly enhanced on RuPd/PG with an initial turnover frequency (TOF0) of 27.2 min-1, possessing superior robustness in recycling tests and actual water samples. Undoubtedly, this work provides new insights into H* generation and reactant activation to optimize ClO3- hydrogenation reduction applicable for water treatment.

Bimetallic Phthalocyanine Monolayers as Promising Materials for Toxic H2S, SO2, and SOF2 Gas Detection: Insights from DFT Calculations

The development of a high-performance gas sensor for the rapid and efficient detection of harmful SF6 decomposition gases (H2S, SO2, and SOF2) is crucial for equipment environmental monitoring and safeguarding human health. In this work, first-principles calculations were conducted to assess the adsorption performance and sensing characteristics of these decomposition gases on two-dimensional metal-dimer-modified phthalocyanine (Mn2Pc, Tc2Pc, and MnTcPc) surfaces. The results demonstrate that the Mn2Pc, Tc2Pc, and MnTcPc monolayers possess enhanced structural stability. The Mn2Pc, Tc2Pc, and MnTcPc monolayer materials show strong adsorption capabilities (|Eads| > 0.90 eV) and significant electron transfer (|Qt| > 0.017 e) and interact favorably with the aforementioned toxic gases, indicating their superior adsorption capacities for SOF2, SO2, and H2S. The microscopic interaction mechanisms between SF6-decomposed gas molecules and the Mn2Pc, Tc2Pc, and MnTcPc nanosheets are elucidated through analyses of electron density distribution, differential charge distribution, and density of states. Furthermore, upon absorption of H2S, SO2, and SOF2, the work function and band gap energy of the Mn2Pc, Tc2Pc, and MnTcPc monolayers undergo significant changes, and the magnetic moments of the Mn2Pc, Tc2Pc, and MnTcPc monolayers also exhibit substantial alterations, suggesting high sensitivity to H2S, SO2, and SOF2. Considering the balance of adsorption strength, sensitivity, and recovery time, the single-layer films of Mn2Pc, Tc2Pc, and MnTcPc are deemed to be gas-sensing materials with significant potential, suitable for the development of sustainable gas sensors targeting H2S, SO2, and SOF2 with effective recovery capabilities.

Harnessing Janus structures: enhanced internal electric fields in C3N5 for improved H2 photocatalysis

Homojunction engineering holds promise for creating high-performance photocatalysts, yet significant challenges persist in establishing and modulating an effective junction interface. To tackle this, we designed and constructed a novel Janus homojunction photocatalyst by integrating two different forms of triazole-based carbon nitride (C3N5). In this design, super-sized, ultrathin nanosheets of carbon-rich C3N5 grow epitaxially on a nitrogen-rich honeycomb network of C3N5, creating a tightly bound and extensive interfacial contact area. This arrangement enhances the built-in internal electric field (IEF) between the two forms of C3N5, facilitating faster directional transfer of photogenerated electrons and improved visible-light harvesting. Consequently, Janus-C3N5 achieves a remarkable H2 evolution rate of 1712.4 μmol h-1 g-1 under simulated sunlight, which is approximately 5.58 times higher than that of bulk C3N5 (306.8 μmol h-1 g-1) and 14.1 times higher than another form of bulk C3N5 (121.2 μmol h-1 g-1). This work offers a new approach to design efficient homojunction-based photocatalysts.

Directed coordination of C/N-termini of cyano group in metal hexacyanoferrates to efficient palladium recovery: Enhanced adsorption affinity and selectivity

N-termini Cyano group (CN) in metal hexacyanoferrates (MHCF) have been identified as specific-affinity sites for palladium (Pd), but C-termini CN do not effectively serve as Pd adsorption sites due to their stronger bonds with the metal ligands (M), which reduces the activity and density of CN. Herein, the optimization of directional coordination of cyano group C/N-termini by modulating the electronic structure of the M (FeII, CoII, and NiII) in MHCF was investigated to reinforce the Pd recovery. Spectroscopic analyses and DFT calculations revealed that NiHCF exhibited N-site mono-coordination, whereas CoHCF displayed C-site mono-coordination due to spin-exchange interactions, leading to the strengthened N-CoIII bonds and weakened FeII-C bonds. Interestingly, FeHCF maintained N-coordination properties and showed C-coordination as the shift of the d-band center weakened the FeIII-C bonds. Double-coordination of CN resulted in a higher adsorption-capacity and -rate than mono-coordination, which were attributed to its greater CN content and adsorption affinity, respectively. Additionally, all three MHCFs, particularly double-coordination FeHCF, demonstrated excellent selectivity in noble/base metal systems, good resistance to anionic interference, and reusability. The study underscores the pivotal role of M's electronic structure in the CN coordination environment, offering a novel strategy for the directional design of adsorbent sites.

Rational design of stable carbon nitride monolayer membranes for highly controllable CO2 capture and separation from CH4 and C2H2

CO2 capture and separation from natural and fuel gas are important industrial issues that refer to the control of CO2 emissions and the purification of target gases. Here, a novel non-planar g-C12N8 monolayer that could be synthesized via the supramolecular self-assembly strategy was identified using DFT calculations. The cohesive energy, phonon spectrum, BOMD, and mechanical stability criteria confirm the stability of the g-C12N8 monolayer. Our DFT calculations and MD simulations designate the g-C12N8 monolayer to perform as a superior CO2 separation membrane from CH4 and C2H2 gas owing to the high CO2 permeability and selectivity. Specifically, the CO2 permeability ranges from 1.21 × 107 to 1.53 × 107 GPU, while the selectivity of CO2/CH4 and CO2/C2H2 is 3.03 × 103 and 3.10 × 102 at 300 K, respectively, much higher than the Robeson upper bound and most of the reported 2D membranes, and even at high temperatures, the g-C12N8 monolayer-based CO2 separation membranes could operate with high performance. Further, at room temperature, the permeated CO2 gas can adsorb on the g-C12N8 surface with moderate adsorption energy and high capacity. These results indicate that the g-C12N8 membrane exhibits high performance for controlling CO2 capture and separation, which inevitably injects a new alternative of novel 2D membranes for CO2 separation and capture from CH4 and C2H2 in light of further experimental and theoretical research.

Integrating spectroscopic analysis and theoretical calculations to elucidate the adsorption efficiency and mechanisms of Cd, Pb, and Cu using novel carboxymethyl cellulose/pectin-based hydrogel beads

Herein, a series of novel carboxymethyl cellulose (CMC)/pectin-based hydrogel beads were synthesized with chitosan as a cross-linker. The hydrogel composites were denoted as CPC-1/2/3/4/5, with varying mass ratios of CMC, pectin, and chitosan (6:0:1, 5:1:1, 4:2:1, 3:3:1, and 2:4:1). This is a pioneering study that investigates the synergistic effects of these biopolymers in a single hydrogel system for the adsorption of heavy metals, specifically Cd2+, Pb2+, and Cu2+. CPC-4 was identified as the optimal adsorbent, and its adsorption behavior, efficiency, and mechanisms were systematically explored. The adsorption kinetics of CPC-4 for Cd2+, Pb2+, and Cu2+ adhered to the pseudo-second-order model, while equilibrium adsorption isotherms were best described by the Langmuir model. Notably, CPC-4 achieved maximum adsorption capacities for Cd2+, Pb2+, and Cu2+ of 139.4, 270.3, and 143.6 mg/g, respectively. Spectroscopic analyses including FTIR and XPS revealed abundant oxygen- and nitrogen-bearing functional groups (carboxyl, hydroxyl, and amine) in CPC-4, which facilitated metal ion binding through complexation reactions. Density functional theory calculations demonstrated that the incorporation of chitosan significantly enhanced the interaction between CMC and pectin, identifying the coupled regions as the most favorable sites for metal adsorption, with adsorption energies of -4.03 eV for Cd, -4.59 eV for Pb, and -5.59 eV for Cu. The superior adsorption performance of CPC-4 is primarily attributed to complexation and hydrogen bonding at the cross-linked sites. In summary, this study highlights the potential of this biopolymer-based hydrogel composite as a promising new adsorbent for the effective management of heavy metal contamination in aquatic environments.

Decomposition Reaction Mechanism of Ammonium Perchlorate on N-Doped Graphene Surfaces: A Density Functional Theory Study

The detailed decomposition pathway of ammonium perchlorate (AP) is important for the design of solid propellants containing AP. In this paper, the possible decomposition reactions of AP upon nitrogen-doped graphene (N-Gr) as a catalyst are investigated via density functional theory. The reaction pathways of HClO4 and NH3 on the N-Gr surface are explored. The decomposition reaction path of the HClO4 molecule on the N-Gr is HClO4 → ClO3- → ClO2- → ClO- → Cl-. The rate-determining step of the process is the Cl-O bond-breaking reaction of ClO2- anions, and the activation energy of the reaction is 0.849 eV. The oxidation of the N-Gr surface promotes the decomposition of both HClO4 and NH3. The OH groups produced during the decomposition process can promote the adsorption and decomposition of NH3. This work provides new insights into the decomposition of AP on N-Gr at the molecular level.

Understanding non-reducible N2 in the mechanism of Mo-nitrogenase

In my proposed mechanism of Mo-nitrogenase there are two roles for separate N2 molecules. One N2 diffuses into the reaction zone between Fe2 and Fe6 where a strategic gallery of H atoms can capture N2 to form the Fe-bound HNNH intermediate which is then progressively hydrogenated through intermediates containing HNNH2, NH and NH2 entities and then two NH3 in sequence. The second N2 can be parked in an N2-pocket about 3.2 Å from Fe2 or bind end-on at the exo coordination site of Fe2. This second N2 is outside the reaction zone, not exposed to H atom donors, and so is 'non-reducible'. Here density functional calculations using a 485+ atom model describe the thermodynamics for non-reducible N2 moving between the N2-pocket and the exo-Fe2 position, for the resting state and 19 intermediates in the mechanism. The entropy component is estimated and included. The result is that for all intermediates with ligation by H or NHx at the endo-Fe2 position the free energy for association of non-reducible N2 at exo-Fe2 is negative. There remains some uncertainty about the status of exo-Fe2-N2 during the step in which H2 exchanges with the incoming reducible N2, where at least two unbound molecules are present. At Fe2 it is evident that attainment of octahedral coordination stereochemistry dominates the binding thermodynamics for non-reducible N2. Possibilities for experimental support of these computational conclusions are discussed.

Dominant Role of Coexisting Ruthenium Nanoclusters Over Single Atoms to Enhance Alkaline Hydrogen Evolution Reaction

Developing efficient and cost-effective electrocatalysts to replace expensive carbon-supported platinum nanoparticles for the alkaline hydrogen evolution reaction remains an important challenge. Recently, an innovative catalyst, composed of ruthenium single atoms (Ru1) integrated with small Ru nanoclusters (RuNC), has attracted considerable attention from the scientific community. However, because of its complexity, this catalyst remains a topic of some debate. Here, a method is reported of precisely controlling the ratios of Ru1 to RuNC on a nitrogenated carbon (NC)-based porous organic framework to produce Ru/NC catalysts, by using different amounts (0, 5, 10 wt.%) of reducing agent. The Ru/NC-10 catalyst, formed with 10 wt.% reducing agent, delivered the best performance under alkaline conditions, indicating that RuNC played a significant role in actual alkaline hydrogen evolution reaction (HER). An anion exchange membrane water electrolyzer (AEMWE) system using the Ru/NC-10 catalyst required a significantly lower operating voltage (1.72 V) than the commercial Pt/C catalyst (1.95 V) to achieve 500 mA cm-2. Moreover, the system can be operated at 100 mA cm-2 without notable performance decay for over 180 h. Theoretical calculations supported these experimental findings that Ru1 contributed to the water dissociation process, while RuNC is more actively associated with the hydrogen recombination process.

Modulating the Coordination Environment of Atomically Dispersed Nickel for Efficient Electrocatalytic CO2 Reduction at Low Overpotentials and Industrial Current Densities

Electrocatalytic CO2-to-CO conversion with a high CO Faradaic efficiency (FECO) at low overpotentials and industrial-level current densities is highly desirable but a huge challenge over non-noble metal catalysts. Herein, graphitic N-rich porous carbons supporting atomically dispersed nickel (NiN4-O sites with an axial oxygen) were synthesized (denoted as O-Ni-Nx-GC) and applied as the cathode catalyst in a CO2RR flow cell. O-Ni-Nx-GC showed excellent selectivity with a FECO over 92% at low overpotentials ranging from 17 to 60 mV, and over 99% at 80 mV. The FECO was ∼100% at industrial-level current densities from 200 to 900 mA·cm-2. Impressively, O-Ni-Nx-GC delivered a state-of-the-art FECO of >96% at 1 A·cm-2 with a turnover frequency of 81.5 s-1 in a 1 M KOH electrolyte. O-Ni-Nx-GC offered excellent stability during long-term operation for 140 h at 100 mA·cm-2, maintaining a FECO > 99%. Mechanism studies revealed that the axial oxygen at the atomically dispersed nickel sites enhanced electron delocalization, with the graphitic N-rich porous carbon support lowering the CO2-to-CO energy barrier and inducing a negative shift in the Ni-3d d-band center, effectively promoting the formation of the *COOH intermediate while weakening the adsorption of the *CO intermediate, thus optimizing the catalytic activity/selectivity to CO under practical conditions.

Enhanced Polysulfide Conversion and Shuttle Suppression in Lithium-Sulfur Batteries via Fe-Phytate Modified Sulfur Cathode

The practical application of lithium-sulfur (Li-S) batteries is severely impeded by poor cycling performance arising from sluggish redox kinetics and the shuttle effect of polysulfides. In this work, novel transition metal phytates are pioneered to functionalize conductive carbon to address these key limitations. Among a series of phytates evaluated, the Fe-Phytate-modified carbon (Fe-PA@CB) demonstrates superior specific capacity and rate performance. The unique molecular-level Fe-PA coating ensures uniform dispersion and increased active site, leveraging optimized adsorption and enhanced catalytic properties. Consequently, the activation energy for polysulfide conversion is significantly reduced, and polarization potential is minimized. The Fe-PA@CB electrode demonstrates significantly improved cycling stability, retaining 61% of the initial capacity after 500 cycles, compared to 40% retention by a conventional carbon-based cathode. This work not only provides a practical solution for enhancing the electrochemical performance of Li-S batteries but also offers valuable insights into material design and mechanistic understanding, paving the way for the development of next-generation energy storage systems.

In-situ construction of high-performance artificial solid electrolyte interface layer on anode surfaces for anode-free lithium metal batteries

The electrochemical performance of lithium metal batteries (LMBs) was hampered by the uncontrolled growth of lithium (Li) dendrites. To address this issue, the extensive application of artificial solid electrolyte interphase (SEI) coatings on anode surfaces emerged as an effective solution. Electrospinning, as an innovative technique for fabricating artificial SEI layers on the surface of copper (Cu) foil, effectively mitigated Li volume strain during cycling. In this study, an electrospun organic-inorganic composite nanofiber membrane was in-situ fabricated on Cu foil, serving as an artificial SEI layer (CuWs) for anode-free LMBs (AF-LMBs) to enhance battery performance. Lithiophilic polyvinylpyrrolidone was used as the polymer matrix, and Cu nitrate served as the inorganic functional particles capable of in-situ redox reactions. The CuWs with their three-dimensional (3D) network structure accommodated electrode volume changes and suppressed Li dendrite growth during Li deposition and stripping. Additionally, CuWs facilitated the in-situ generation of Li nitrate (LiNO3), which helped stabilize SEI layer and enhance Li utilization. The release sites of LiNO3 on the nanofibers enabled the in-situ reduction of metallic Cu, providing nucleation sites for Li deposition and forming the 3D ion-electron hybrid conductive networks. This CuWs layer reduced interfacial resistance and nucleation barriers, promoting uniform Li+ distribution on the anode surface. Li-Cu cells incorporating CuWs exhibited remarkable cycling stability, enduring over 460 cycles at 1.0 mA cm-2 and 1.0 mAh cm-2 with an average Coulombic efficiency of over 98.6 %. In Li-poor cells, the LFP|PE|CuWs achieved stable cycling for more than 30 cycles at 1.0 C, with a capacity retention rate of 92.0 %. These findings demonstrated that the CuWs membrane significantly enhanced the electrochemical performance of Li-poor cells and provided a novel artificial SEI protective strategy for advanced AF-LMBs with high energy density.

Three-dimensional, multi-functionalized nanocellulose/alginate hydrogel for efficient and selective phosphate scavenging: Optimization, performance, and in-depth mechanisms

Challenges in developing adsorbents with sufficient phosphate (P) adsorption capacity, selectivity, and regeneration properties remain to be addressed. Herein, a multi-functionalized high-capacity nanocellulose/alginate hydrogel (La-NCF/SA-PEI [La: lanthanum, NCF: nanocellulose fiber, SA: sodium alginate, PEI: polyethyleneimine]) was prepared through environmentally friendly methods. The La-NCF/SA-PEI hydrogel, featuring a 3D porous structure with interwoven functional groups (amino, quaternary ammonium, and lanthanum), demonstrated a maximum P adsorption capacity of 78.0 mg/g, exceeding most La-based hydrogel adsorbents. The kinetic and isotherm fitting results confirmed the multilayer chemisorption process. Comprehensive experimental results, instrumental analysis, and computational results revealed that the ammonium phosphate complex (NH3+-O-P) and the inner-sphere complex (La-O-P) formed by La(OH)3 dominated the selective P adsorption process. Density-functional theory (DFT) was employed to calculate the bond length between phosphate and each component of the La-NCF/SA-PEI. The calculation results revealed the double-bridge adsorption between the N (apex) atom on La-NCF/SA-PEI and the O (apex) atomic site in phosphate, including electrostatic adsorption and two hydrogen bonds (bond lengths 1.001 and 1.008 Å) between the O of PO43- and the H+ of the protonated amino group. Except the remarkable P adsorption performance (both municipal sewage and aquaculture tail water), the La-NCF/SA-PEI hydrogel's high selectivity toward P, environmental compatibility, and easy separability from water underscore its significant potential for phosphate-contaminated water remediation. The multi-functionalized La-NCF/SA-PEI demonstrate promising potential for P removal applications and advanced the development of sustainable, biomass-based adsorbents design.

Chiral Separation and Determination of Multiple Organophosphorus Pesticide Enantiomers in Soil Based on Cellulose-Based Chiral Column by LC-MS/MS

The widespread use of organophosphorus pesticides (OPs) has raised significant environmental and health concerns due to their residues in soil and potential entry into the food chain. This study introduced chiral analysis methods for four OPs-methamidophos (METHP), dipterex (DIP), malathion (MALA), and isothiophos-methyl (ISOME)-using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with cellulose-based chiral columns. Three distinct methods were established: one for METHP, another for DIP, and a third for MALA and ISOME. Key chromatographic variables, including organic mobile phases and column temperatures, were systematically optimized, achieving maximum resolutions (Rs) of 1.61 for METHP, 2.40 for DIP, 1.70 for MALA, and 2.02 for ISOME. The QuEChERS method was employed for sample pretreatment, ensuring high recoveries. All three methods demonstrated excellent linearity (R > 0.998), accuracy with recoveries ranging from 79% to 121%, precision with RSD% < 11%, and sensitivity with low limits of enantiomer detection (LODs) as low as 0.17 µg/kg for METHP, 0.087 µg/kg for DIP, 0.062 µg/kg for MALA, and 0.054 µg/kg for ISOME, representing a sensitivity improvement of 16-172 times compared to existing methods. Field soil samples from Yangzizhou District, Nanchang, China, revealed significant contamination by ISOME, with concentrations of a single enantiomer reaching up to 8343 µg/kg, while MALA exhibited varying enantiomeric ratios with depth. This study provides robust analytical tools for monitoring chiral OP residues in soil, contributing to food safety and environmental protection.

Modelling of a new form of nitrogen doped activated carbon for adsorption of various dyes and hexavalent chromium ions

This study reports a new form of nitrogen-doped activated carbon (AC5-600) produced from a blend of sawdust (SD) and fish waste (FW) treated with urea and ZnCl2 for the adsorption of toxic metals and dyes. The adsorbent was also explored in the treatment of acid brown 14 (AB14) and acid orange 7 (AO7) dye molecules and hexavalent chromium (Cr6+) ions. The pH controls the sorption of individual contaminants, with an observed superlative % of individual contaminants removed at pH 1.5. Removal at pH was credited to the electrostatic interaction (EI) between the anion dyes and Cr6+ species at this pH and the protonated sites accessible on the AC5-600 adsorbent surface. Based on the error values obtained from the non-linear modelling (NLM) of the kinetic and isotherm models, the Elovich (ELM-AB14 and Cr6+), pseudo-first- (PFOM-AB14) and second-order models (PSOM-AB14, AO7 and Cr6+) and the Freundlich (FRHM) model were found to ideally define the sorption of the various contaminants. The determined maximum sorption capacity (Qm) based on the NLM was 1114, 1929 and 318 mg.g-1 for AB14 dye, AO7 dye and Cr6+ ions, respectively. Based on the computational adsorption calculations, the sorption energies for the AO7 and AB14 dyes were -4.492 and -8.090 eV and 2.563, 1.789, 1.226 and 1.928 eV for Cr2, CrO3, CrO4, and CrO4H species. AB14 and AO7 dyes and Cr6+ ions adsorption to synthesised AC5-600 was predicted employing the response surface methodology (RSM) and artificial neural network (ANN) models. The ANN model was more effective in predicting AB14 and AO7 dyes and Cr6+ ions adsorption than the RSM, and it was highly applicable in the sorption process.

Selective Adsorption of Thiol-Containing Molecules on Copper Sulfide Surfaces via Molecule-Surface Disulfide Bridges

Recent results in the fields of nanoenhanced agriculture and expanding interest in prebiotic chemistry have placed increased emphasis on understanding the chemically selective interaction of small molecules with the surfaces of metal sulfides. We present an integrated experimental and computational study of the interaction of thiol-containing molecules with copper sulfide (covellite) surfaces in aqueous media. In situ Fourier-transform infrared (FTIR) measurements and ex situ X-ray photoelectron spectroscopy (XPS) measurements show that molecules bearing free thiol groups, including glutathione and cysteine, bind strongly to CuS (covellite) nanoparticles and to CuS (001) single crystals, while control studies show that similar molecules lacking the free thiol group exhibit much less binding. Additional experiments show that these thiol-containing molecules interact transiently with CuO nanoparticle surfaces but are readily removed by rinsing. The FTIR and XPS experiments demonstrate that adsorption of molecular thiols to CuS surfaces occurs in a chemically selective manner. Further experimental studies and density functional calculations show that the preferred mode of binding is through the surface S atoms, forming a Solid-S-S-Molecule disulfide linkage. While the role of disulfide linkages in controlling structure and function of proteins and other biomolecules is widely known, the formation of surface disulfide linkages as a motif for covalent molecular binding at surfaces has not been established previously.

Dual-Anion-Rich Polymer Electrolytes for High-Voltage Solid-State Lithium Metal Batteries

Solid polymer electrolytes (SPEs) are promising candidates for lithium metal batteries (LMBs) owing to their safety features and compatibility with lithium metal anodes. However, the inferior ionic conductivity and electrochemical stability of SPEs hinder their application in high-voltage solid-state LMBs (HVSSLMBs). Here, a strategy is proposed to develop a dual-anion-rich solvation structure by implementing ferroelectric barium titanate (BTO) nanoparticles (NPs) and dual lithium salts into poly(vinylidene fluoride) (PVDF)-based SPEs for HVSSLMBs. The BTO NPs regulate the spatial structure of PVDF segments, enhancing the local built-in electric field in the SPEs, which, in turn, facilitates the dissolution and dissociation of lithium salts. This contributes to the dual-anion-rich solvation structure with an enhanced steric effect, which significantly improves Li+ transport kinetics and electrochemical stability. The designed PVDF-based SPE achieves a high ionic conductivity of 4.1 × 10-4 S cm-1 and a transference number of 0.70 at 25 °C. The Li//Li symmetric cells deliver an excellent critical current density of 2.4 mA cm-2 and maintain a stable Li plating/stripping process for over 5000 h. After 1000 cycles at 2C, the LiFePO4//Li cells achieve a discharge capacity of 108.3 mAh g-1. Furthermore, the LiNi0.8Co0.1Mn0.1O2 (NCM811)//Li cells present high capacity retention after 300 cycles at 1C with a cutoff voltage of 4.4 V. The NCM811/Graphite pouch batteries exhibit excellent cycling and safety performance. This work illustrates that the synergistic integration of functional nanoparticles with multiple lithium salts holds significant potential for the development of high-voltage SPEs.

Ptn (n = 1, 3, and 4) Cluster-Modified MoSe2 Nanosheets: A Potential Sensing and Scavenging Candidate for Lithium-Ion Battery State Characteristic Gases

Realizing reliable online detection of characteristic gases (H2, C2H4, CO, and CO2) in lithium-ion batteries is crucial to maintain the safe and stable operation of power equipment and new energy storage power plants. In this study, transition metal Ptn (n = 1, 3, and 4) clusters are attached to MoSe2 nanosheets for the first time based on density functional theory using the perfect crystalline facet modification method, and the adsorption characteristics and electronic behaviors of H2, C2H4, CO, and CO2 are investigated and enhanced. The results show that Ptn (n = 1, 3, and 4) is reliably chemically connected to the substrate without any significant deformation of the geometry. The adsorption properties as well as the band gap, DOS, and LUMO-HOMO are optimized for the modified Gas/Ptn (n = 1, 3, and 4)-MoSe2 system. The large electronic states near the Fermi level are further activated by the modification process, and Pt-MoSe2 and Pt4-MoSe2 can serve as battery state characteristic gas sensors suitably according to the detection needs of specific target gases, whereas Pt3-MoSe2 can be used as a good adsorbent for effective and reliable scavenging of battery state characteristic gases and is further applied to energy and power equipment and new energy storage power plants.

Atomic locations and adsorbate interactions of Al single and pair sites in H-ZSM-5 zeolite

The distribution of substitutional aluminum (Al) atoms in zeolites affects molecular adsorbate geometry, catalytic activity, and shape and size selectivity. Accurately determining Al positions has been challenging. We used synchrotron resonant soft x-ray diffraction (RSXRD) at multiple energies near the Al K-edge combined with molecular adsorption techniques to precisely locate "single Al" and "Al pairs" in a commercial H-ZSM-5 zeolite. This analysis depicts three distinct Al tetrahedral (T) sites: T8, T6, and T4. A combined suite of characterizations, including ammonia temperature-dependent desorption, neutron powder diffraction, solid-state nuclear magnetic resonance spectroscopy, and density functional theory calculations, reveal isolated ammonia adsorption on T8 as "single Al" in the straight channel and bridged ammonia adsorption on T6 and T4 as an "Al pair" (AlT6-O-SiT5-O-AlT4) in the straight-sinusoidal intersection.

A Kagome Lattice of Lanthanide Atoms in a 2D Er-Directed Metal-Organic Coordination Network

Kagome lattices have attracted much attention due the very interesting properties they can exhibit, both from the electronic and the magnetic points of view, although much of the experimental studies have been reported on 3D metals or 2D nanosheets. In the past few years, on-surface synthesis has allowed the fabrication of strictly monolayer 2D metal-organic networks, many of them containing transition metals. In this paper we report the fabrication and the study of the electronic and magnetic properties of a monolayer 2D metal-organic network where the nodes are lanthanide atoms forming a kagome lattice.

Multilayered screening for multi-targeted anti-Alzheimer's and anti-Parkinson's agents through structure-based pharmacophore modelling, MCDM, docking, molecular dynamics and DFT: a case study of HDAC4 inhibitors

Abstract

Alzheimer's disease (AD) and Parkinson's disease (PD) are neurological conditions that primarily impact the elderly having distinctive traits and some similarities in terms of symptoms and progression. The multifactorial nature of AD and PD encourages exploring potentiality of multi-target therapy for addressing these conditions to conventional, the "one drug one target" strategy. This study highlights the searching of potential HDAC4 inhibitors through multiple screening approaches. In this context, structure-based pharmacophore model, ligand profiler mapping and MCDM approaches were performed for target prioritization. Similarly, ligand profiler, MCDM and Docking studies were performed to prioritize multi-targeted HDAC4 inhibitors. These comprehensive approaches unveiled 5 common targets and 5 multi-targeted prioritized compounds consensually. MD simulations, DFT and binding free energy calculations corroborated the stability and robustness of propitious compound 774 across 5 prioritized targets. In conclusion, the screened compound 774 (ChEMBL 4063938) could be a promising multi-targeted therapy for managing AD and PD further rendering experimental validation.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00302-4.

Rhodamine based turn-on dual mode chemosensor for the selective recognition of nickel ions: practical and theoretical applications

This work presents the development of a rhodamine-based colorimetric and turn-on fluorescent chemosensor (P1) designed for selective recognition of Ni2+ ions. Chemosensor P1 exhibited remarkable sensitivity and selectivity for Ni2+ ions, exhibiting clear colorimetric and fluorescence responses. The binding interactions were meticulously examined using UV-Vis. and fluorescence spectroscopy, demonstrating a 1 : 1 stoichiometric ratio between P1 and Ni2+ ions via a Job's plot and Benesi-Hildebrand analysis, while the binding constant and limit of detection were established as 0.8919 × 104 M-1, and 2.15 nM, respectively. Interference studies demonstrated that competing metal ions had a minimal effect on the selectivity of the sensor. Chemosensor P1 showed practical applicability by fabricating paper strips and solid-state silica gel systems, facilitating the rapid and visible detection of Ni2+ ions. Their stability and effectiveness were confirmed under a wide range of pH conditions. A molecular INHIBIT logic gate was created utilizing Ni2+ and EDTA as inputs in conjunction with memory devices featuring a "write-read-erase-read" binary logic function, highlighting P1's capabilities in logic-based sensing and data storage. Furthermore, P1 demonstrated reversible binding to Ni2+ in the presence of EDTA, enhancing its versatility. Density Functional Theory (DFT) calculations offered valuable insights into the molecular interactions, while the analysis of actual juice samples confirmed the efficacy of P1 for detecting Ni2+ in complex matrices, making it an exceptional candidate for advanced environmental and analytical sensing technologies with outstanding selectivity and versatility.

Electric-Field Controlled Switchable and Efficient Separation of Radioactive Xe/Kr on Borophene: A Theoretical Study

The efficient and reversible separation of radioactive Xe/Kr during spent fuel reprocessing is important and challenging for the rapid development of nuclear energy. In this study, we firstly report a strategy of applying an electric field on the solid adsorbent borophene to realize efficient and switchable Xe/Kr separation via a density functional theory (DFT) investigation. Based on the calculational results, the adsorption energies for Xe and Kr on borophene without an electric field are -0.25 eV and -0.18 eV, respectively, indicating that Xe and Kr can only form weak adsorption on borophene. However, by applying an electric field (0.006 a.u.) to the systems, the adsorption energies for Xe and Kr on borophene are -0.98 eV and -0.47 eV, respectively, which shows that the interaction between Xe and borophene has increased dramatically compared with that of Kr, so Xe can be separated from radioactive Xe/Kr mixtures. What's more, when the electric field is removed, desorption of Xe from the surface of borophene is exothermic without an energy barrier. The adsorbent is recyclable. In summary, this theoretical study provides novel information for experimental researches, the highly efficient Xe/Kr separation can be controlled by turning on/off the applied electric field.

Scaffolding and Heavy-Atom Effects of Metal Chains Enhanced Tunable Long Persistent Luminescence in Metal-Organic Frameworks

Metal-organic frameworks (MOFs) with long persistent luminescence (LPL) have attracted extensive research attention due to their potential applications in information encryption, anticounterfeiting technology, and security logic. The strategic combinations of organic phosphor linkers and metal ions lead to tremendous frameworks, which could unveil many undiscovered properties of organics. Here, the synthesis and characterization of a three-dimensional MOF (Cd-MOF) is reported, which demonstrates enhanced blue photoluminescence and a phosphorescent lifetime of 124 ms as compared to the pristine linker (H2L) under ambient conditions due to the scaffolding and heavy-atom effects of metal chains in the framework. Notably, the Cd-MOF exhibits intriguing excitation-, time-, and temperature-dependent LPL, with a duration of 3 s at room temperature and the ability to shift from blue to green to yellow at lower temperatures. Optical characterizations and theoretical calculations reveal that H2L molecules are responsible for the emissions in the Cd-MOF, while LPL properties of molecular phosphors can be significantly enhanced and regulated through coordination interactions and heavy-atom effect of the metal chains. This work highlights the potential of such materials as promising candidates for multiple anticounterfeiting, displaying, and encryption applications.

Ternary Eutectic Electrolyte for Flexible Wide-Temperature Zinc-Ion Batteries from -20 °C to 70 °C

Aqueous Zn-ion batteries (ZIBs) have attracted attention for grid applications due to their cost-effectiveness and high security. However, their lifespan decreases at high temperatures due to declining interfacial stability and increased side reactions. To address these challenges, a ternary deep eutectic solvent-based flexible electrolyte, comprised of Zn(ClO4)2 ⋅ 6H2O, butanedinitrile (BD), and LiCl in an amphoteric polymer matrix, was developed to enable wide-temperature ZIBs working from -20 °C to 70 °C. The interactions among BD, Li+, and zinc hydrate alongside the amphoteric groups on the polyelectrolyte matrix could effectively suppress the interfacial side reactions and Zn dendrites formation. Consequently, the symmetric Zn cell demonstrates exceptional stability across a wide-temperature range, with the ability to survive up to 2780 hours (1 mA cm-2) at 50 °C. Furthermore, the flexible Zn||PANI battery can operate stably over 1000 cycles at 50 °C, boasting an initial specific capacity of 124.8 mAh g-1 and capacity retention rate of 87.9 % (3 A g-1). This work presents an effective strategy for designing high-stability energy storage devices with excellent security features that can function reliably across diverse temperature conditions.

N-P Type Charge Compensatory Synergistic Effect for Schottky and Efficient Photoelectrocatalysis Applications: Doping Mechanism in (Nb/Re)@WS2/Graphene Heterojunctions

Band gap engineering based on doped two-dimensional (2D) transition metal dichalcogenides (TMDs) has shown great potential in the design and development of new nano photoelectronic devices and their application in photoelectrocatalysis. However, there are two key issues that are difficult to take into account, namely the impurity levels induced by dopant atoms appear in the forbidden band of the doping system, which can become the recombination center of photogenerated carriers, thereby reducing the photocatalytic efficiency. Compared with the carrier mobility of the corresponding doped systems, that of intrinsic 2D TMDs is too low. Understanding the doping mechanism of heteroatoms in these systems and designing corresponding crystal structures rationally is important for solving these problems. In this study, the crystal structures of co-doped monolayer WS2 with Nb and Re atoms were designed using density functional theory, and doping systems with graphene (high carrier mobility) were assembled into a heterostructure using the concept of heterorecombination. The N-P type co-doping of Nb and Re atoms retained the continuous band characteristics of the original monolayer WS2 while also providing the high carrier mobility of graphene, yielding an excellent multipurpose material for manufacturing high-speed Schottky devices and efficient water-splitting H evolution catalysts.

Assessment of the potential and application of Be12O12 nanocage for removal of ciprofloxacin from water employing density functional theory

The modern world is facing the issue of emerging pollutants for its sustainable development. We report a detailed study on the abatement of ciprofloxacin (CIP) by Be12O12 nanocage. Five different geometries of Be12O12 nanocage with CIP i.e., Com-A, Com-B, Com-C, Com-D and Com-E are optimized. All the complexes show chemisorption with the highest adsorption energies (Eads) of - 39.86 kcal/mol for Com-E followed by Com-A, Com-B, Com-C and Com-D without any structural change. The O and F atoms of ciprofloxacin (CIP) interacts strongly with the Be atoms of the nanocage respectively. Charge transfer from the nanocage to CIP reveals strong interaction in all the optimized complexes, with maximum charge transfer of -0.199 e for Com-E with the smallest bond lengths of 1.52 Å and 1.63 Å. The decrease in the bandgap of the optimized geometries witnesses increase in the sensing ability of the adsorbent and demonstrates strong interaction between the adsorbent and adsorbate supporting the adsorption energies. The positive values of Hb and ∇2ρb for all complexes reveals strong interaction of electrostatic nature between CIP and Be12O12 nature which is supported by different tools of DFT. The overall study suggests Be12O12 an efficient, reusable adsorbent for the purification of water from CIP and therefore Be12O12 can be used effectively to eliminate antibiotics from water.

B92: a complete coating icosahedral B12 core-shell structure

Using first-principles calculations, this study unveils a spherically aromatic core-shell B12@B80 structure featuring a B12 icosahedral core, which is the smallest complete coating icosahedral B12 core-shell Bn cluster to date. Detailed orbital and bonding analyses reveal that the icosahedral B12 core exhibits prominent superatomic behavior with the electronic configuration 1S21P61D101F8.

Metal-Mediated Chlorine Transfer for Molten Salt-Driven Thermodynamic Change on Silicon Production

The development of silicon (Si) material poses a great challenge with profound technological advancements for semiconductors, photo/photoelectric systems, solar cells, and secondary batteries. Typically, Si production involves the thermochemical reduction of silicon oxides, where chloride salt additives help properly revamp the reaction mechanism. Herein, we unravel the chemical principles of molten AlCl3 salt in metallothermic reduction. Above its melting temperature (Tm ≈ 192 °C), three AlCl3 molecules coordinate with each metal (M) atom (e.g., conventional Al and Mg, or even thermodynamically unfeasible Zn) to form metal-AlCl3 complexes, M(AlCl3)3. In the molten AlCl3 salt media, all complexes directly lead to the universal formation of AlOCl byproduct and as-reduced Si spheres through internal Cl* transfer during the reduction reaction. Intriguingly, highly oxophilic metal (i.e., Mg) establishes additional energetic shortcuts in reaction pathways, where AlCl3 directly detaches an oxygen atom, accompanied by strong metal-oxygen interactions and Cl* transfer within the same complex. Moreover, the thermodynamic stability of the metal-AlCl3 complex residue (MAl2Cl8) and the microstructure of post-treated Si do change according to the metal choice, imparting disparate physicochemical properties for Si. This work offers insights into the scalable production of tailored Si materials for industrial applications, along with cost-effective operations at 250 °C.

Improving Fast-Charging Performance of Lithium-Ion Batteries through Electrode-Electrolyte Interfacial Engineering

The solid-electrolyte interphase (SEI) is a key element in anode-electrolyte interactions and ultimately contributes to improving the lifespan and fast-charging capability of lithium-ion batteries. The conventional additive vinyl carbonate (VC) generates spatially dense and rigid poly VC species that may not ensure fast Li+ transport across the SEI on the anode. Here, a synthetic additive called isosorbide 2,5-dimethanesulfonate (ISDMS) with a polar oxygen-rich motif is reported that can competitively coordinate with Li+ ions and allow the entrance of PF6 - anions into the core solvation structure. The existence of ISDMS and PF6 - in the core solvation structure along with Li+ ions enables the movement of anions toward the anode during the first charge, leading to a significant contribution of ISDMS and LiPF6 to SEI formation. ISDMS leads to the creation of ionically conductive and electrochemically stable SEI that can elevate the fast-charging performance and increase the lifespan of LiNi0.8Co0.1Mn0.1O2 (NCM811)/graphite full cells. Additionally, a sulfur-rich cathode-electrolyte interface with a high stability under elevated-temperature and high-voltage conditions is constructed through the sacrificial oxidation of ISDMS, thus concomitantly improving the stability of the electrolyte and the NCM811 cathode in a full cell with a charge voltage cut-off of 4.4 V.

The Analysis of Vibrational Spectra: Past, Present and Future

Vibrational spectroscopy can be said to have started with the seminal work of Coblentz in the 1900s, who recorded the first recognisable infrared spectra. Today, vibrational spectroscopy is ubiquitous and there are many ways to measure a vibrational spectrum. But this is usually only the first step, almost always there is a need to assign the resulting spectra: "what property of the system results in a feature at this energy"? How this question has been answered has changed over the last century, as our understanding of the fundamental physics of matter has evolved. In this Perspective, I will present my view of how the analysis of vibrational spectra has evolved over time. The article is divided into three sections: past, present and future. The "past" section consists of a very brief history of vibrational spectroscopy. The "present" is centered around ab initio studies, particularly with density functional theory (DFT) and I will describe how this has become almost routine. For the "future", I will extrapolate current trends and also speculate as to what might come next.

Acylhydrazone Functionalized Triphenylamine-Based Fluorescent Probe for Cu2+: Tunable Structures of Conjugated Bridge and Its Practical Application

Novel fluorescent probes were constructed for the convenient and rapid analysis of Cu2+ ions, taking advantages of the the triphenylamine backbone as chromophore and acylhydrazone group as the Cu2+ recognition site. Especially, probe T2 could act as a dual-channel probe towards Cu2+ through both fluorescent and colorimetric method. Through the fluorescent method, the detection limit of probe T2 was calculated to be as low as 90 nmol/L and there was a good linear relationship between the intensity change and the concentration of Cu2+ ions. By virtue of the two-phase liquid-liquid extraction method, probe T2 could be successfully applied in practical extraction and separation of Cu2+. Furthermore, by applying a "turn-off-turn-on" circle, compound T2 could act as a sensitive probe towards S2- anions through the indirect approach and the detection limit of complex T2-Cu2+ for S2- anion was found to be 110 nmol/L.

Rapid Detection of Aluminium and Iron Impurities in Lithium Carbonate Using Water-Soluble Fluorescent Probes

The real-time measurement of the content of impurities such as iron and aluminium ions is one of the keys to quality evaluation in the production process of high-purity lithium carbonate; however, impurity detection has been a time-consuming process for many years, which limits the optimisation of the production of high-purity lithium carbonate. In this context, this work explores the possibility of using water-soluble fluorescent probes for the rapid detection of impurity ions. Salicylaldehyde was modified with the hydrophilic group dl-alanine to synthesise a water-soluble Al3+ fluorescent probe (Probe A). Moreover, a water-soluble Fe3+ fluorescent probe (Probe B) was synthesised from coumarin-3-carboxylic acid and 3-hydroxyaminomethane. Probe A and Probe B exhibited good stability in the pH range of 4-9 in aqueous solutions, high sensitivity, as well as high selectivity for Al3+ and Fe3+; the detection limits for Al3+ and Fe3+ were 1.180 and 1.683 μmol/L, whereas the response times for Al3+ and Fe3+ were as low as 10 and 30 s, respectively. Electrostatic potential (ESP) analysis and density functional theory calculations identified the binding sites and fluorescence recognition mechanism; theoretical calculations showed that the enhanced fluorescence emission of Probe A when detecting Al3+ was due to the excited intramolecular proton transfer (ESIPT) effect, whereas the fluorescence quenching of Probe B when detecting Fe3+ was due to the electrons turning off fluorescence when binding through the photoelectron transfer (PET) mechanism.