Design and Evolution of an Artificial Friedel-Crafts Alkylation Enzyme Featuring an Organoboronic Acid Residue

Creating artificial enzymes by the genetic incorporation of noncanonical amino acids with catalytic side chains would expand the enzyme chemistries that have not been discovered in nature. Here, we report the design of an artificial enzyme that uses p-boronophenylalanine as the catalytic residue. The artificial enzyme catalyzes Michael-type Friedel-Crafts alkylation through covalent activation. The designer enzyme was further engineered to afford high yields with excellent enantioselectivities. We next developed a practical method for preparative-scale reactions by whole-cell catalysis. This enzymatic C-C bond formation reaction was combined with palladium-catalyzed dearomative arylation to achieve the efficient synthesis of spiroindolenine compounds.

N-Heteroatom Engineered Nonporous Amorphous Self-Assembled Coordination Cages for Capture and Storage of Iodine

Radioactive iodine isotopes from nuclear-related activities, present substantial risks to human health and the environment. Developing effective materials for the capture and storage of these hazardous molecules is paramount. Traditionally, nonporous solids were historically considered ineffective for adsorbing target species. In this study, we investigate the potential of four nonporous, amorphous, self-assembled coordination cages (C1, C2, C3, and C4) featuring varying numbers of nitrogen atoms within the core (pyridyl/triazine unit) and specific cavity sizes for iodine adsorption. These coordination cages demonstrate remarkable adsorption abilities for iodine in both vapor and solution phases, facilitated by enhanced electron-pair interactions. The cages exhibit high uptake capacities of up to 3.16 g g-1 at 75 °C, the highest among metal-organic cages and up to 434.29 mg g-1 in solution, highlighting the efficiency of these materials across different phases. Even at ambient temperature, they show significant iodine capture efficiency, with a maximum value of 1.5 g g-1. Furthermore, these robust materials can be recycled, enduring at least five reusable cycles without apparent fatigue. Overall, our findings present a "N-heteroatom engineering" approach for the development of recyclable amorphous containers for the capture and storage of iodine, contributing to the mitigation of nuclear-related risks.

Controlled bioorthogonal activation of Bromodomain-containing protein 4 degrader by co-delivery of PROTAC and Pd-catalyst for tumor-specific therapy

The precise and safe treatment of bioorthogonal prodrug system is hindered by separate administration of prodrug and its activator, which often results in poor therapeutic effects and severe side effects. To address above issues, we herein construct a single bioorthogonal-activated co-delivery system for simultaneous PROTAC prodrug (proPROTAC) delivery and controlled, site-specific activation for tumor-specific treatment. In this co-delivery system (termed AuPLs), prodrug (proPROTAC) and water-soluble Pd-catalyst are first encapsulated by gold nanocubes (AuNCs), which are further coated with a layer of phase-change material (lauric acid/stearic acid, LA/SA). Below 39 °C, the solid state of LA/SA prevents the activation of Pd-mediated bioorthogonal reaction due to the solidification of Pd-catalyst and proPROTAC. Nevertheless, once over 42 °C, the phase change of LA/SA into liquid state, enabled by the photothermal effect of AuNCs, triggers the simultaneous release of proPROTAC and Pd-catalyst and initiates the in situ bioorthogonal reaction for proPROTAC activation. In the tumor-bearing mouse models, the systemic administration of AuPLs results in the accumulation in tumor region, where the photothermal effect activates and controls the tumor-specific bioorthogonal reaction to degrade BRD4 protein, leading to anti-tumor effects with minimized side effects. Overall, the co-delivery proPROTAC and Pd-catalyst and controlled activation by photothermal effects provide a precise way for biorthogonal-based anticancer prodrugs.

Direct catalytic oxidation of rice husk lignin with hydroxide nanorod-modified copper foam and muconate production by engineered Pseudomonas sp. NGC7

For the direct alkaline oxidation of rice husk lignin, we developed a copper foam-based heterogeneous catalyst that offers advantages in its recovery after the reaction mixture. The depolymerized products were utilized for muconate production by an engineered Pseudomonas sp. NGC7-based strain. A hydroxide nanorod-modified copper foam was prepared by the surface oxidation of copper foam, followed by alkaline oxidation of rice husk lignin over the catalyst. The catalyst was easily separated from the cellulosic residues in the reaction mixture, and the residues were then recovered by filtration. The resulting lignin stream was composed of a variety of aromatic monomers containing p-hydroxyphenyl, guaiacyl, and syringyl compounds. The catabolic activity of Pseudomonas sp. NGC7 was demonstrated to be more suitable for muconate production from a mixture comprising 4-hydroxybenzoate (a typical p-hydroxyphenyl compound), vanillate (a guaiacyl compound), and syringate (a syringyl compound), owing to its natural ability to grow on syringate. Thus, it was applied to produce muconate from a rice husk lignin stream prepared through hydroxide nanorod-modified copper foam-catalyzed alkaline oxidation by conferring the genes responsible for converting the acetophenone derivatives to their corresponding aromatic acids and protocatechuate decarboxylase to an NGC7-based strain deficient in protocatechuate 3,4-dioxygenase and muconate cycloisomerase. As a result, the engineered NGC7-based muconate-producing strain produced muconate selectively from the rice husk lignin stream at 93.7 mol% yield.

Synergistic Modulation of Multiple Sites Boosts Anti-Poisoning Hydrogen Electrooxidation Reaction with Ultrasmall (Pt0.9Rh0.1)3V Ternary Intermetallic Nanoparticles

Promoting the hydrogen oxidation reaction (HOR) activity and poisoning tolerance of electrocatalysts is crucial for the large-scale application of hydrogen-oxygen fuel cell. However, it is severely hindered by the scaling relations among different intermediates. Herein, lattice-contracted Pt-Rh in ultrasmall ternary L12-(Pt0.9Rh0.1)3V intermetallic nanoparticles (~2.2 nm) were fabricated to promote the HOR performances through an oxides self-confined growth strategy. The prepared (Pt0.9Rh0.1)3V displayed 5.5/3.7 times promotion in HOR mass/specific activity than Pt/C in pure H2 and dramatically limited activity attenuation in 1000 ppm CO/H2 mixture. In situ Raman spectra tracked the superior anti-CO* capability as a result of compressive strained Pt, and the adsorption of oxygen-containing species was promoted due to the dual-functional effect. Further assisted by density functional theory calculations, both the adsorption of H* and CO* on (Pt0.9Rh0.1)3V were reduced compared with that of Pt due to lattice contraction, while the adsorption of OH* was enhanced by introducing oxyphilic Rh sites. This work provides an effective tactic to stimulate the electrocatalytic performances by optimizing the adsorption of different intermediates severally.

Predicting Activation of Small Molecules Including Dinitrogen via a Carbene with a σ0π2 Electronic Configuration

Although the main group species in the s and p blocks have begun to gain prominence in the field of dinitrogen (N2) activation in recent years, reports of carbene-mediated N2 activation remain particularly rare, especially for carbenes with a σ0π2 electronic configuration. Herein, we demonstrate examples of N2 activation initiated by a carbene with a σ0π2 electronic configuration and consequent N2 hydroboration reaction (with a reaction barrier as low as 19.9 kcal/mol) via density functional theory calculations. Meanwhile, the "push-pull" electronic effect upon introduction of a hydroborenium complex facilitates the generation of a thermodynamically and kinetically more stable product. In addition, such a σ0π2 carbene can also activate a series of H-X (X = H, CH3, or Bpin) bonds through an oxidative addition process with activation energies ranging from 6.0 to 18.0 kcal/mol. Our findings highlight the importance of σ0π2 carbenes in the field of small molecule activation, especially N2 activation.

Tuning Catalytic Activity of CO2 Hydrogenation to C1 Product via Metal Support Interaction Over Metal/Metal Oxide Supported Catalysts

The metal supported catalysts are emerging catalysts that are receiving a lot of attention in CO2 hydrogenation to C1 products. Numerous experiments have demonstrated that the support (usually an oxide) is crucial for the catalytic performance. The support metal oxides are used to aid in the homogeneous dispersion of metal particles, prevent agglomeration, and control morphology owing to the metal support interaction (MSI). MSI can efficiently optimize the structural and electronic properties of catalysts and tune the conversion of key reaction intermediates involved in CO2 hydrogenation, thereby enhancing the catalytic performance. There is an increasing attention is being paid to the promotion effects in the catalytic CO2 hydrogenation process. However, a systematically understanding about the effects of MSI on CO2 hydrogenation to C1 products catalytic performance has not been fully studied yet due to the diversities in catalysts and reaction conditions. Hence, the characteristics and modes of MSI in CO2 hydrogenation to C1 products are elaborated in detail in our work.

Elucidating the Discrepancy between the Intrinsic Structural Instability and the Apparent Catalytic Steadiness of M-N-C Catalysts toward Oxygen Evolution Reaction

Despite the widespread investigations on the M-N-C type single atom catalysts (SACs) for oxygen evolution reaction (OER), an internal conflict between its intrinsic thermodynamically structural instability and apparent catalytic steadiness has long been ignored. Clearly unfolding this contradiction is necessary and meaningful for understanding the real structure-property relation of SACs. Herein, by using the well-designed pH-dependent metal leaching experiments and X-ray absorption spectroscopy, an unconventional structure reconstruction of M-N-C catalyst during OER process was observed. Combining with density functional theory calculations, the initial Ni-N coordination is easily broken in the presence of adsorbed OH*, leading to favorable formation of Ni-O coordination. The formed Ni-O works stably as the real active center for OER catalysis in alkaline media but unstably in acid, which clearly explains the existing conflict. Unveiling the internal contradiction between structural instability and catalytic steadiness provides valuable insights for rational design of single atom OER catalysts.

Structural Degradation of M-N-C (M=Co, Ni and Fe) Single-Atom Electrocatalysts at Industrial-Grade Current Density for Long-Term Reduction

M-N-C single-atom catalysts (SACs) are promising electrode materials for many electro-reduction reactions. However, their stability is far from practical applications, and their deactivation mechanism has been rarely investigated. Herein, we demonstrate the structural degradation of M-N-C (M=Co, Ni, and Fe) at industrial-grade current density for long-term electro-reduction. Both M-N and N-C bonds are broken, resulting in the gradual hydrogenation and dissolution of N in the form of ammonia. The residual M is finally converted to M-containing core-shell nanoparticles after sequential dissolution, redeposition, and electro-reduction. The destruction of the M-N-C structure and the formation of nanoparticles greatly affect the electrocatalytic performance. Our work highlights the structural degradation and deactivation mechanism of M-N-C-type SACs under strong reductive conditions and provides useful information for inspiring researchers to develop new strategies to improve the electrocatalytic stability of similar types of materials.

A Merger of Relay Catalysis with Dynamic Kinetic Resolution Enables Enantioselective β-C(sp3)-H Arylation of Alcohols

The conceptual merger of relay catalysis with dynamic kinetic resolution strategy is reported to enable regio- and enantioselective C(sp3)-H bond arylation of aliphatic alcohols, forming enantioenriched β-aryl alcohols typically with >90 : 10 enantiomeric ratios (up to 98 : 2 er) and 36-74 % yields. The starting materials bearing neighbouring stereogenic centres can be converted to either diastereomer of the β-aryl alcohol products, with >85 : 15 diastereomeric ratios determined by the catalysts. The reactions occur under mild conditions, ensuring broad compatibility, and involve readily available aryl bromides, an inorganic base, and commercial Ru- and Pd-complexes. Mechanistic experiments support the envisioned mechanism of the transformation occurring through a network of regio- and stereoselective processes operated by a coherent Ru/Pd-dual catalytic system.

Interfacial Ir-V Direct Metal Bonding Enhanced Hydrogen Evolution Activity in Vanadium Oxides Supported Catalysts

Tuning the interfacial structure of metal oxide substrates is an essential strategy to induce electronic structure reconstruction of supported catalysts, which is of great importance in optimizing their catalytic activities. Herein, vanadium oxides-supported Ir catalysts (Ir-V2O3, Ir-VO2, and Ir-V2O5) with different interfacial bonding environments (Ir-V, Ir-Obri, and Ir-O, respectively) were investigated for hydrogen evolution reaction (HER). The regulating mechanism of the influence of different interfacial bonding environments on HER activity was investigated by both experimental results and computational evidence. Benefiting from the unique advantages of interfacial Ir-V direct metal bonds in Ir-V2O3, including enhanced electron transfer and electron donation ability, an optimized HER performance can be obtained with lowest overpotentials of 16 and 26 mV at 10 mA cm-2, high mass activities of 11.24 and 6.66 A mg-1, and turnover frequency values of 11.20 and 6.63 s-1, in acidic and alkaline conditions respectively. Furthermore, the assembled Ir-V2O3||RuO2 anion exchange membrane (AEM) electrolyzer requires only 1.92 V to achieve a high current density of 500 mA cm-2 and realizes long-term stability. This study provides essential insights into the regulating mechanism of interfacial chemical bonding in electrocatalysts and offers a new pathway to design noble metal catalysts for different applications.

Boron-Induced Interstitial Effects Drive Water Oxidation on Ordered Ir-B Compounds

Interstitial filling of light atoms strongly affects the electronic structure and adsorption properties of the parent catalyst due to ligand and ensemble effects. Different from the conventional doping and surface modification, constructing ordered intermetallic structures is more promising to overcome the dissolution and reconstruction of active sites through strong interactions generated by atomic periodic arrangement, achieving joint improvement in catalytic activity and stability. However, for tightly arranged metal lattices, such as iridium (Ir), obtaining ordered filling atoms and further unveiling their interstitial effects are still limited by highly activated processes. Herein, we report a high-temperature molten salt assisted strategy to form the intermetallic Ir-B compounds (IrB1.1) with ordered filling by light boron (B) atoms. The B residing in the interstitial lattice of Ir constitutes favorable adsorption surfaces through a donor-acceptor architecture, which has an optimal free energy uphill in rate-determining step (RDS) of oxygen evolution reaction (OER), resulting in enhanced activity. Meanwhile, the strong coupling of Ir-B structural units suppresses the demetallation and reconstruction behavior of Ir, ensuring catalytic stability. Such B-induced interstitial effects endow IrB1.1 with higher OER performance than commercial IrO2, which is further validated in proton exchange membrane water electrolyzers (PEMWEs).

Diatomic Iron with a Pseudo-Phthalocyanine Coordination Environment for Highly Efficient Oxygen Reduction over 150,000 Cycles

Atomically dispersed Fe-N-C catalysts emerged as promising alternatives to commercial Pt/C for the oxygen reduction reaction. However, the majority of Fe-N-C catalysts showed unsatisfactory activity and durability due to their inferior O-O bond-breaking capability and rapid Fe demetallization. Herein, we create a pseudo-phthalocyanine environment coordinated diatomic iron (Fe2-pPc) catalyst by grafting the core domain of iron phthalocyanine (Fe-Nα-Cα-Nβ) onto defective carbon. In situ characterizations and theoretical calculation confirm that Fe2-pPc follows the fast-kinetic dissociative pathway, whereby Fe2-pPc triggers bridge-mode oxygen adsorption and catalyzes direct O-O radical cleavage. Compared to traditional Fe-N-C and FePc-based catalysts exhibiting superoxo-like oxygen adsorption and an *OOH-involved pathway, Fe2-pPc delivers a superior half-wave potential of 0.92 V. Furthermore, the ultrastrong Nα-Cα bonds in the pPc environment endow the diatomic iron active center with high tolerance for reaction-induced geometric stress, leading to significantly promoted resistance to demetallization. Upon an unprecedented harsh accelerated degradation test of 150,000 cycles, Fe2-pPc experiences negligible Fe loss and an extremely small activity decay of 17 mV, being the most robust candidate among previously reported Fe-N-C catalysts. Zinc-air batteries employing Fe2-pPc exhibit a power density of 255 mW cm-2 and excellent operation stability beyond 440 h. This work brings new insights into the design of atomically precise metallic catalysts.

The improvement of heat transfer using Co/SiO2 spiral structured catalyst for green diesel production by Fischer-Tropsch synthesis

In this study, the improvement of heat transfer was applied to eliminate hotspots of a highly exothermic reaction, Fischer-Tropsch synthesis (FTS), by means of two facile methods: (I) adding high thermal conductive materials media diluted in catalysts (SiC and Al chips), and (II) using structured reactors equipped with well-designed structured catalysts with advantages of heat dissipation/removal. The 20%Co/SiO2 catalyst powder prepared by simple impregnation was employed for constructing structured catalysts and granular packed bed catalysts. The structured catalyst was prepared by coating method of Co/SiO2 slurry on an aluminum spiral and plate substrate. The catalytic performance of as-prepared catalysts was then tested for FTS in a fixed-bed reactor at 210-230 °C, 20 bar. Both gaseous and liquid products were collected and analyzed. The heat transfer improvement of packed bed catalytic system and structured catalytic system were compared and discussed. As a result, the structured catalytic system with spiral structured catalyst can provide the best improvement of heat/mass transfer, resulting in enhanced diesel selectivity, though the oil production rate was unsatisfactory. Meanwhile, among the packed bed catalytic systems, SiC media possessed the best heat removal material, producing the highest oil yield. In addition, the fresh and spent catalysts were analyzed by several techniques including TEM, SEM, XRD, BET, ICP-OES, H2-TPR, and TGA to relate the physicochemical properties of the prepared catalysts and its FTS performance.

Phase Engineering of High-Entropy Alloy for Enhanced Electrocatalytic Nitrate Reduction to Ammonia

Directly electrochemical conversion of nitrate (NO3 -) is an efficient and environmentally friendly technology for ammonia (NH3) production but is challenged by highly selective electrocatalysts. High-entropy alloys (HEAs) with unique properties are attractive materials in catalysis, particularly for multi-step reactions. Herein, we first reported the application of HEA (FeCoNiAlTi) for electrocatalytic NO3 - reduction to NH3 (NRA). The bulk HEA is active for NRA but limited by the unsatisfied NH3 yield of 0.36 mg h-1 cm-2 and Faradaic efficiency (FE) of 82.66 %. Through an effective phase engineering strategy, uniform intermetallic nanoparticles are introduced on the bulk HEA to increase electrochemical active surface area and charge transfer efficiency. The resulting nanostructured HEA (n-HEA) delivers enhanced electrochemical NRA performance in terms of NH3 yield (0.52 mg h-1 cm-2) and FE (95.23 %). Further experimental and theoretical investigations reveal that the multi-active sites (Fe, Co, and Ni) dominated electrocatalysis for NRA over the n-HEA. Notably, the typical Co sites exhibit the lowest energy barrier for NRA with *NH2 to *NH3as the rate-determining step.

Stereodivergent Construction of 1,5/1,7-Nonadjacent Tetrasubstituted Stereocenters Enabled by Pd/Cu-Cocatalyzed Asymmetric Heck Cascade Reaction

The construction of chiral motifs containing nonadjacent stereocenters in an enantio- and diastereoselective manner has long been a challenging task in synthetic chemistry, especially with respect to their stereodivergent synthesis. Herein, we describe a protocol that enables the enantio- and diastereoselective construction of 1,5/1,7-nonadjacent tetrasubstituted stereocenters through a Pd/Cu-cocatalyzed Heck cascade reaction. Notably, a C=C bond relay strategy involving the shift of the π-allyl palladium intermediate was successfully applied in the asymmetric construction of 1,7-nonadjacent stereocenters. The current method allows for the efficient preparation of chiral molecules bearing two privileged scaffolds, oxindoles and non-natural α-amino acids, with good functional group tolerance. The full complement of the four stereoisomers of products bearing 1,5/1,7-nonadjacent stereocenters could be readily accessed by a simple combination of two chiral metal catalysts with different enantiomers.

Triggering Heteroatom Ensemble Effect over RuFe Alloy to Promote Nitrogen Chemisorption for Efficient Ammonia Electrosynthesis at Ambient Conditions

Ammonia (NH3) electrosynthesis from nitrogen (N2) provides a promising strategy for carbon neutrality, circumventing the energy-intensive and carbon-emitting Haber-Bosch process. However, the current system still presents unsatisfactory performance, and the bottleneck lies in the rational synthesis of catalytic centers with efficient N2 chemisorption ability. Herein, a heteroatom ensemble effect is deliberately triggered over RuFe alloy with spatial proximity of metal sites to promote electrocatalytic nitrogen reduction. The heteronuclear RuFe ensemble with increased surface polarization and modulated electronic structure offers the feasibility to optimize the adsorption configuration of electroactive substances and facilitate chemical bond scission. The promotion of N2 chemisorption and the following hydrogenation are demonstrated by the in situ Fourier transform infrared spectroscopy characterizations. The catalyst thus permits significantly enhanced conversion of N2 to NH3 in a 0.1 M HCl environment, with a maximum ammonia yield rate of 75.45 μg h-1 mg-1 and a high Faradaic efficiency of 35.49%.

Modulation Excitation Spectroscopy: A Powerful Tool to Elucidate Active Species and Sites in Catalytic Reactions

ConspectusA rational design of catalysts requires a knowledge of the active species and sites. Often, catalyst surfaces are dominated by spectators, which do not participate in the reaction, while the catalytically active species and sites are hidden. Modulation-excitation spectroscopy (MES) allows discrimination between active and spectator species by applying a concentration modulation, which is translated into the active (that is, actively responding) species by phase-sensitive detection (PSD).While MES has been known for a while, its combination with infrared spectroscopy (IR-MES) has been applied to the detailed mechanistic analysis of a wide range of supported metal and metal oxide catalysts only recently, used for catalytic reactions such as CO2 hydrogenation, water-gas shift, and CO and selective oxidation. The applicability of IR-MES is not limited to catalysis but has started to expand into other areas of research (e.g., gas sensing).In the context of renewable energy, CO2 hydrogenation has been a matter of intense mechanistic debate, despite its great importance for synthesis gas production and further processing to fuels and chemicals. Applying IR-MES to supported Cu and Au catalysts enabled us to discriminate between redox and associative mechanisms. While CO2 hydrogenation to CO and water follows an associative pathway with sequential H2 activation via hydrides and formation of carbon- and oxygen-containing intermediates, such as carbonates and formates, the reverse reaction, that is, the water-gas shift reaction, was shown to proceed via a redox mechanism including oxygen vacancy formation followed by reoxidation of the catalyst by CO2.Recent IR-MES studies on (supported) metal oxides have provided direct spectroscopic insight into the catalytically active sites during the selective oxidation of alkanes and alcohols. By further expanding the potential of IR-MES by transient isotopic exchange experiments, we were able to resolve the nuclearity-dependent vanadium and adsorbate dynamics of supported vanadia catalysts during oxidative dehydrogenation, highlighting the intimate interplay between the surface vanadia species and the support. The strong influence of the support material (ceria and titania) on the sequence of reaction steps provides an explanation for the different catalytic performance. Based on these mechanistic insights, the rational design of improved catalysts has been possible.Expanding the application of IR-MES to the area of gas sensing, as recently demonstrated for doped SnO2, provides access to enhanced mechanistic insight, including previously undetected surface species. Methodical challenges arising from background features associated with semiconductor metal oxides have been successfully tackled, supporting further expansion of IR-MES in the gas sensing community. Mechanistically, the application of IR-MES allows identification of the actively participating OH groups and adsorbed species (e.g., alkoxy, CO, carbonate) and monitoring of reaction sequences based on their temporal behavior, providing a level of understanding typically not accessible by steady-state methods.As outlined above, the combination of MES/PSD with IR spectroscopy constitutes a powerful approach for the identification of catalytically active species and sites, which is essential for a profound mechanistic understanding of surface reactions, greatly facilitating the rational design of catalysts and other functional materials.

Unveiling Highly Sensitive Active Site in Atomically Dispersed Gold Catalysts for Enhanced Ethanol Dehydrogenation

Developing a desirable ethanol dehydrogenation process necessitates a highly efficient and selective catalyst with low cost. Herein, we show that the "complex active site" consisting of atomically dispersed Au atoms with the neighboring oxygen vacancies (Vo) and undercoordinated cation on oxide supports can be prepared and display unique catalytic properties for ethanol dehydrogenation. The "complex active site" Au-Vo-Zr3+ on Au1/ZrO2 exhibits the highest H2 production rate, with above 37,964 mol H2 per mol Au per hour (385 g H2 g Au - 1 ${{\rm{g}}_{{\rm{Au}}}^{ - 1} }$  h-1) at 350 °C, which is 3.32, 2.94 and 15.0 times higher than Au1/CeO2, Au1/TiO2, and Au1/Al2O3, respectively. Combining experimental and theoretical studies, we demonstrate the structural sensitivity of these complex sites by assessing their selectivity and activity in ethanol dehydrogenation. Our study sheds new light on the design and development of cost-effective and highly efficient catalysts for ethanol dehydrogenation. Fundamentally, atomic-level catalyst design by colocalizing catalytically active metal atoms forming a structure-sensitive "complex site", is a crucial way to advance from heterogeneous catalysis to molecular catalysis. Our study advanced the understanding of the structure sensitivity of the active site in atomically dispersed catalysts.

Perspective on Lignin Conversion Strategies That Enable Next Generation Biorefineries

The valorization of lignin, a currently underutilized component of lignocellulosic biomass, has attracted attention to promote a stable and circular bioeconomy. Successful approaches including thermochemical, biological, and catalytic lignin depolymerization have been demonstrated, enabling opportunities for lignino-refineries and lignocellulosic biorefineries. Although significant progress in lignin valorization has been made, this review describes unexplored opportunities in chemical and biological routes for lignin depolymerization and thereby contributes to economically and environmentally sustainable lignin-utilizing biorefineries. This review also highlights the integration of chemical and biological lignin depolymerization and identifies research gaps while also recommending future directions for scaling processes to establish a lignino-chemical industry.

Enantioselective Synthesis of Sulfinamidines via Asymmetric Nitrogen Transfer from N-H Oxaziridines to Sulfenamides

Sulfinamidines are promising aza-SIV chiral building blocks in asymmetric synthesis and drug discovery. However, no report has documented their enantioselective synthesis. Here we present an enantioselective synthesis of sulfinamidines via electrophilic amination of sulfenamides using an enantiopure N-H oxaziridine. The resulting enantiomerically enriched primary sulfinamidines are configurationally stable at 90 °C in solution and show remarkable stability against organic acids and bases under non-aqueous conditions. We also demonstrate a one-pot, three-component, enantioselective synthesis of sulfinamides using N-H oxaziridine reagents.

Electroreduction of CO to 2.8 A cm⁻2 C2+ Products: Maximizing Efficiency with Minimalist Electrode Design Featuring a Mesopore-Rich Hydrophobic Copper Catalyst Layer

This work shows how hydrophobicity and porosity can be incorporated into copper catalyst layers (CLs) for the efficient electroreduction of CO (CORR) in a flow cell. Oxide-derived (OD) Cu catalysts are synthesized using K+ and Cs+ as templates, termed respectively as OD-Cu-K and OD-Cu-Cs. CLs, assembled from OD-Cu-K and OD-Cu-Cs, exhibit enhanced CORR performance compared to "unmodified" OD-Cu CL. OD-Cu-Cs can notably reduce CO to C2+ products with Faradaic efficiencies (FE) as high as 96% (or 4% FE H2). During CO electrolysis at -3000 mA cm-2 (-0.73 V vs reversible hydrogen electrode), C2+ products and the alcohols are formed with respective current densities of -2804 and -1205 mA cm- 2. The mesopores in the OD-Cu-Cs CL act as barriers against electrolyte flooding. Contact angle measurements confirm the CL's hydrophobicity ranking: OD-Cu-Cs > OD-Cu-K > OD-Cu. The enhanced hydrophobicity of a catalyst is proposed to allow more triple-phase (CO-electrolyte-catalyst) interfaces to be available for CORR. This study shows how the pore size-hydrophobicity relationship can be harvested to guide the design of a less-is-more Cu electrode, which can attain high CORR current density and selectivity, without the additional use of hydrophobic polytetrafluoroethylene particles or dopants, such as Ag.

Unifying the ORR and OER with surface oxygen and extracting their intrinsic activities on platinum

Common half-cell measurements deliver oxygen reduction activities linked to the chosen scan rate, limiting their value for fundamental and comparative studies on platinum. Here we show a deconvolution of the intrinsic kinetics from the effect of surface oxygen on platinum. We find an electronic effect of the surface oxygen, substantiate a Tafel slope of ~120 mV/decade, obtain an exchange current density of 13 ± 4 µA/cm2, and an activity of 7 mA/cm2 at 900 mV. Eventually, we broaden the scope of this analysis to the effects of surface rearrangement, alloying, and supported Pt nanoparticles, the latter providing insight into discrepancies between half-cell and fuel cell measurements. We find through computational methods that binding energies of intermediates would be weakened by the presence of highly coordinated oxygen atoms. Finally, we obtain a phenomenological rate equation for the oxygen reduction and evolution reaction, suggesting that both reactions follow a shared mechanism.

Hydroformylation of Olefins with CO2/H2 and Hydrosilane by Copper/Cobalt Tandem Catalysis

A Cu/Co tandem catalysis protocol was developed to conduct the hydroformylation of olefins using CO2/H2 and PMHS (polymethylhydrosiloxane) as a readily available and environmentally friendly hydride source. This methodology was performed via a two-step approach consisting of the copper-catalyzed reduction of CO2 by hydrosilane and subsequent cobalt-promoted hydroformylation with H2 and the in situ formed CO. The optimized triphos oxide ligand, which presumably facilitates the migratory insertion of CO gives moderate to excellent yields for both terminal and internal alkenes. This earth-abundant metal catalysis provides a reliable and efficient way to afford useful aldehydes in industry using silicon by-product PMHS as hydrogen source and renewable CO2 as carbonyl source.

Multi-metallic Layered Catalysts for Stable Electrochemical CO2 Reduction to Formate and Formic Acid

Electrochemical CO2 reduction (ECR) to value-added products such as formate/formic acid is a promising approach for CO2 mitigation. Practical ECR requires long-term stability at industrially relevant reduction rates, which is challenging due to the rapid degradation of most catalysts at high current densities. Herein, we report the development of a bismuth (Bi) gas diffusion electrode on a polytetrafluoroethylene-based electrically conductive silver (Ag) substrate (Ag@Bi), which exhibits high Faradaic efficiency (FE) for formate of over 90 % in 1 M KOH and 1 M KHCO3 electrolytes. The catalyst also shows high selectivity of formic acid above 85 % in 1 M NaCl catholyte, which has a bulk pH of 2-3 during ECR, at current densities up to 300 mA cm-2. In 1 M KHCO3 condition, Ag@Bi maintains formate FE above 90 % for at least 500 hours at the current density of 100 mA cm-2. We found that the Ag@Bi catalyst degrades over time due to the leaching of Bi in the NaCl catholyte. To overcome this challenge, we deposited a layer of Ag nanoparticles on the surface of Ag@Bi to form a multi-layer Ag@Bi/Ag catalyst. This designed catalyst exhibits 300 hours of stability with FE for formic acid ≥70 % at 100 mA cm-2. Our work establishes a new strategy for achieving the operational longevity of ECR under wide pH conditions, which is critical for practical applications.

Growing highly ordered Pt and Mn bimetallic single atomic layers over graphdiyne

Controlling the precise growth of atoms is necessary to achieve manipulation of atomic composition and atomic position, regulation of electronic structure, and an understanding of reactions at the atomic level. Herein, we report a facile method for ordered anchoring of zero-valent platinum and manganese atoms with single-atom thickness on graphdiyne under mild conditions. Due to strong and incomplete charge transfer between graphdiyne and metal atoms, the formation of metal clusters and nanoparticles can be inhibited. The size, composition and structure of the bimetallic nanoplates are precisely controlled by the natural structure-limiting effect of graphdiyne. Experimental characterization clearly demonstrates such a fine control process. Electrochemical measurements show that the active site of platinum-manganese interface on graphdiyne guarantees the high catalytic activity and selectivity (~100%) for alkene-to-diol conversion. This work lays a solid foundation for obtaining high-performance nanomaterials by the atomic engineering of active site.

Efficient C(sp3)-H Bond Oxidation on Perovskite Quantum Dots Based on Ce-Oxygen Affinity

Perovskite quantum dots (QDs) have shown attractive prospects in the field of visible photocatalysis, especially in the synthesis of high value-added chemicals. However, under aerobic conditions, the stable operation of QD catalysts has been limited by the reactive oxygen species (ROS) generated by photoexcitation, especially superoxide species O2⋅-. Here, we propose a strategy of Ce3+ doping in perovskite QDs to guide superoxide species for photocatalytic oxidation reactions. In C(sp3)-H bond oxidation of hydrocarbons, superoxide species were rapidly generated and efficiently utilized on the surface of perovskite QDs, which achieves the stable operation of the catalytic system and obtains a high product conversion rate (15.3 mmol/g/h for benzaldehydes). The mechanism studies show that the strong Ce-oxygen affinity accelerates the relaxation process of photoinduced exciton transfer to superoxide species and inhibits the radiative recombination pathway. This work provides a new idea of utilizing oxygen species on perovskite surface and broadens the design strategy of high-performance QD photocatalysts.

Highly Active Oxidation Catalysts through Confining Pd Clusters on CeO2 Nano-Islands

CeO2-supported noble metal clusters are attractive catalytic materials for several applications. However, their atomic dispersion under oxidizing reaction conditions often leads to catalyst deactivation. In this study, the noble metal cluster formation threshold is rationally adjusted by using a mixed CeO2-Al2O3 support. The preferential location of Pd on CeO2 islands leads to a high local surface noble metal concentration and promotes the in situ formation of small Pd clusters at a rather low noble metal loading (0.5 wt %), which are shown to be the active species for CO conversion at low temperatures. As elucidated by complementary in situ/operando techniques, the spatial separation of CeO2 islands on Al2O3 confines the mobility of Pd, preventing the full redispersion or the formation of larger noble metal particles and maintaining a high CO oxidation activity at low temperatures. In a broader perspective, this approach to more efficiently use the noble metal can be transferred to further systems and reactions in heterogeneous catalysis.

Alloy Reconstruction in Pyrolytic Bowknot-like Heteronuclear CoFe Clusters for Electrocatalytic Application

The construction of doped molecular clusters is an intriguing way to perform bimetallic doping for electrocatalysts. However, efficiently harnessing the benefits of a doping strategy and alloy engineering to create a nanostructure for electrocatalytic application at the molecular level has consistently posed a challenge. Here we propose an in situ reconstruction strategy aimed at producing an alloy nanostructure through a pyrolysis process, originating from bowknot-like heterometallic clusters. The Schiff base, denoted as ligand L1 (o-vanillin ethylenediamine), was introduced as a precursor to coordinate Fe and Co metals, thereby yielding a heteronuclear metal cluster [(FeCo)(L1)2O]CH3CN. Subsequently, a comprehensive investigation of the in situ reconstruction process [(FeCo)(L1)2O](CH3CN) → [(FeCo)(L1)2O] → [M-O-M/M-O] [CH3+/CH3O+/H2C═N/C2H5+/C4H4+] → [FeCo/Fe3O4/Fe2O3/Co3O4][carbon layer] led to the formation of MOx/CoFe@NC-700 during the pyrolysis. This process reveals that the metals Fe and Co in the clusters undergo partly in situ evolution into FeCo alloys, resulting in the successful preparation of MOx/CoFe@NC (M = Fe, Co) nanomaterials that leverage the advantages of both doping strategies and alloy engineering. The synergistic interaction between alloy particles and metal oxides establishes active sites that contribute to the excellent oxygen evolution (OER) and hydrogen evolution (HER) catalytic behaviors. Notably, these materials exhibit outstanding OER and HER properties under alkaline conditions, with overpotentials of 191 and 88 mV for OER and HER, respectively, at 10 mA cm-2. Investigation of the in situ conversion of Schiff base bimetal clusters into alloy materials through pyrolysis offers a novel strategy for advancing electrocatalytic applications.

Strain-Driven Phase Transitions in Delafossite Cu1-xAxAlO2: A Key to Enhanced Photo(electro)catalytic Performance

This study investigates the impact of intrinsic strain and phase transitions on the thermodynamic stability and electronic properties of Cu1-xAxAlO2 solid solutions, which are key to their photocatalytic performance. It is demonstrated that Cu1-xAxAlO2 with A = Ag, Au, Pt can form continuous isostructural solid solutions due to relatively small compressive strain, while a substantial increase strain restricts Cu1-xPdxAlO2 to forming only limited solutions. For A = Li, Na, the formation of heterostructural solid solutions is facilitated by structural motif alterations, accommodating significant differences in ionic radii and A-O bond characteristics. Specifically, Cu1-xLixAlO2 exhibits a phase transition at x ≈ 0.333, whereas Cu1-xNaxAlO2 undergoes three distinct phase transitions. Electronic structure analysis indicates that in Cu1-xAxAlO2 (A = Ag, Au), d10-d10 closed-shell interactions dominate, enabling tunable band gaps with varying solubility. Nevertheless, increased intrinsic strain in metal sublattices, as seen in A = Pd and Pt, shifts antibonding states to the Fermi level, inducing a semiconductor-to-metal transition. Experimental evidence confirms that Ag+ ions modulate the band gaps and carrier dynamics in Cu1-xAgxAlO2, with Cu0.75Ag0.25AlO2 exhibiting heightened photoelectrochemical activity and a 38.5-fold enhancement in H2 production rate over CuAlO2. Additionally, the coordination environment changes between alkali metals and O, induced by phase transitions, effectively tune the band edge positions and carrier dynamics of Cu1-xAxAlO2 (A = Li, Na) heterostructural solid solutions. Therefore, 3R-Cu0.97Li0.03AlO2 with asymmetric nonlinear dumbbell O-Cu-O demonstrates the highest photocatalytic H2 production activity, 72.9 times greater than CuAlO2. In contrast, α-Cu1-xAxAlO2 with a smaller CuO6 octahedral splitting energy exhibits increased band gaps, resulting in diminished photocatalytic activity. This research underscores that strain-driven phase transition provides an additional control factor and new mechanism for regulating the photo(electro)catalytic activity of Cu1-xAxAlO2 solid solutions.

Tuning the Electronic Structures of Anchor Sites to Achieve Zero-Valence Single-Atom Catalysts for Advanced Hydrogenation

Single-atom catalysts (SACs) have recently become highly attractive for selective hydrogenation reactions owing to their remarkably high selectivity. However, compared to their nanoparticle counterparts, atomically dispersed metal atoms in SACs often show inferior activity and are prone to aggregate under reaction conditions. Here, by theoretical calculations, we show that tuning the local electronic structures of metal anchor sites on g-C3N4 by doping B atoms (BCN) with relatively lower electronegativity allows achieving zero-valence Pd SACs with reinforced metal-support orbital hybridizations for high stability and upshifted Pd 4d orbitals for high activity in H2 activation. The precise synthesis of Pd SACs on BCN supports with varied B contents substantiated the theoretical prediction. A zero-valence Pd1/BCN SAC was achieved on a BCN support with a relatively low B content. It exhibited much higher stability in a H2 reducing environment, and more strikingly, a hydrogenation activity, approximately 10 and 34 times greater than those high-valence Pd1/g-C3N4 and Pd1/BCN with a high B content, respectively.

Photocatalytic CO2 Reduction to Ethanol by ZnCo2O4/ZnO Janus Hollow Nanofibers

Photocatalytic carbon dioxide (CO2) reduction for high-value hydrocarbon fuel production is a promising strategy to tackle global energy demand and climate change. However, this technology faces formidable challenges, primarily stemming from low yield and poor selectivity of C2 products of the desired hydrocarbon fuels. This study reported ZnO/ZnCo2O4 Janus hollow nanofibers (ZnO/ZCO JHNFs) prepared by electrospinning and atomic layer deposition. Photocatalytic tests revealed an ethanol yield of 4.99 μmol g-1 h-1 for ZnO/ZnCo2O4 JHNFs, surpassing mixed ZnO/ZnCo2O4 nanofibers (ZnO/ZCO NFs) by 4.35 times and pure ZnO by 12.7 times. The selectivity of 58.8% is 2.38 and 4.49 times higher than those of ZnO/ZnCo2O4 NFs and ZnO, respectively. These enhancements are attributed to efficient carrier separation facilitated by the ordered internal electric field of the Z-scheme heterojunction interface, validated by the energy band evaluations from experimentation and density functional theory (DFT) simulations and charge separation characterizations of photocurrent, impedance, and photoluminescence spectra. The Janus structure also effectively exposes the surface of ZnCo2O4 to CO2 molecules, increasing the active site availability, as confirmed by BET nitrogen adsorption/desorption, temperature-programmed desorption tests, and DFT adsorption energy calculations. This study proposes a novel approach for efficient photocatalytic hydrocarbon fuel production, with potential applications in energy and climate crisis mitigation.

Constructing an artificial in vitro multi-enzyme cascade pathway to convert glycerol and CO2 into L-aspartic acid

Developing utilization technologies for biomass resources, exploring their applications in the fields of energy and chemical engineering, holds significant importance for promoting sustainable development and constructing a green, low-carbon society. In this study, we designed a non-natural in vitro multi-enzyme system for converting glycerol and CO2 into L-aspartic acid (L-Asp). The coupled system utilized eight enzymes, including alditol oxidase (ALDO), catalase-peroxidase (CAT), lactaldehyde dehydrogenase (ALDH), glycerate 2-kinase (GK), phosphopyruvate hydratase (PPH), phosphoenolpyruvate carboxylase (PPC), L-aspartate dehydrogenase (ASPD), and polyphosphate kinase (PPK), to convert the raw materials into L-Asp in one-pot coupled with NADH and ATP regeneration. Under optimal reaction conditions, 18.6 mM of L-Asp could be produced within 2.0 h at a total enzyme addition of 4.85 mg/mL, demonstrating the high efficiency and productivity characteristics of the designed system. Our technological application provides new insights and methods for the development of biomass resource utilization technologies.

Arginine-Modified Hemin Enhances G-Quadruplex DNAzyme Peroxidase Activity for High Sensitivity Detection

Hemin/G-quadruplex (hG4) complexes are frequently used as artificial peroxidase-like enzymatic systems (termed G4 DNAzymes) in many biosensing applications, in spite of a rather low efficiency, notably in terms of detection limits. To tackle this issue, we report herein a strategy in which hemin is chemically modified with the amino acids found in the active site of parent horseradish peroxidase (HRP), with the aim of recreating an environment conducive to high catalytic activity. When hemin is conjugated with a single arginine, it associates with G4 to create an arginine-hemin/G4 (R-hG4) DNAzyme that exhibits improved catalytic performances, characterized by kinetic analysis and DFT calculations. The practical relevance of this system was demonstrated with the implementation of biosensing assays enabling the chemiluminescent detection of G4-containing DNA and colorimetry detection of the flap endonuclease 1 (FEN1) enzyme with a high efficiency and sensitivity. Our results thus provide a guide for future enzyme engineering campaigns to create ever more efficient peroxidase-mimicking DNA-based systems.

Atomic-Dispersed Cu Catalysts for Electrochemical Nitrate Reduction: Coordination Engineering and Fundamental Insights

The development of Cu-based atomic dispersed catalysts with tailored coordination environments represents a significant step forward in enhancing the electrocatalytic reduction of nitrate to ammonia. By precisely modulating the electronic structures of Cu active centers, the binding strength of the *NO3 intermediates is successfully tuned, thereby substantially improving the catalytic activity toward electrochemical nitrate reduction reaction (eNO3RR). This study reveals that the N4-coordinated Cu single-atom catalyst (Cu-SAC) exhibits superior performance due to its robust interaction with coordinating atoms. Notably, this optimized catalyst achieves a low limiting potential of -0.38 V, while the dual-atom system further reduces this value to -0.32 V, demonstrating exceptional activity. Detailed electronic structure analysis, including the examination of d-band centers, Bader charges, and projected density of states (PDOS), provides a comprehensive understanding of the origin of this high activity. Specifically, the high and concentrated density of states near the Fermi level plays a crucial role in facilitating the electrocatalytic nitrate reduction process. This work not only offers crucial insights into the underlying mechanisms of eNO3RR but also provides valuable guidelines for the rational design of highly efficient electrocatalysts for this important reaction.

Suppressing Surface Oxidation of Pyrite FeS2 by Cobalt Doping in Lithium Sulfur Batteries

Lithium-sulfur batteries have emerged as a promising energy storage device due to ultra-high theoretical capacity, but the slow kinetics of sulfur and polysulfide shuttle hinder the batteries' further development. Here, the 10% cobalt-doped pyrite iron disulfide electrocatalyst deposited on acetylene black as a separator coating in lithium-sulfur batteries is reported. The adsorption rate to the intermediate Li2S6 is significantly improved while surface oxidation of FeS2 is inhibited: iron oxide and sulfate, thus avoiding FeS2 electrocatalyst deactivation. The electrocatalytic activity has been evaluated in terms of electronic resistivity, lithium-ion diffusion, liquid-liquid, and liquid-solid conversion kinetics. The coin batteries exhibit ultra-long cycle life at 1 C with an initial capacity of 854.7 mAh g-1 and maintained at 440.8 mAh g-1 after 920 cycles. Furthermore, the separator is applied to a laminated pouch battery with a sulfur mass of 326 mg (3.7 mg cm-2) and retained the capacity of 590 mAh g-1 at 0.1 C after 50 cycles. This work demonstrates that FeS2 electrocatalytic activity can be improved when Co-doped FeS2 suppresses surface oxidation and provides a reference for low-cost separator coating design in pouch batteries.

Non-Noble-Metal-Based Electrocatalysts for Acidic Oxygen Evolution Reaction: Recent Progress, Challenges, and Perspectives

The oxygen evolution reaction (OER) plays a pivotal role in diverse renewable energy storage and conversion technologies, including water electrolysis, electrochemical CO2 reduction, nitrogen fixation, and metal-air batteries. Among various water electrolysis techniques, proton exchange membrane (PEM)-based water electrolysis devices offer numerous advantages, including high current densities, exceptional chemical stability, excellent proton conductivity, and high-purity H2. Nevertheless, the prohibitive cost associated with Ir/Ru-based OER electrocatalysts poses a significant barrier to the broad-scale application of PEM-based water splitting. Consequently, it is crucial to advance the development of non-noble metal OER catalysis substance with high acid-activity and stability, thereby fostering their widespread integration into PEM water electrolyzers (PEMWEs). In this review, a comprehensive analysis of the acidic OER mechanism, encompassing the adsorbate evolution mechanism (AEM), lattice oxygen mechanism (LOM) and oxide path mechanism (OPM) is offered. Subsequently, a systematic summary of recently reported noble-metal-free catalysts including transition metal-based, carbon-based and other types of catalysts is provided. Additionally, a comprehensive compilation of in situ/operando characterization techniques is provided, serving as invaluable tools for furnishing experimental evidence to comprehend the catalytic mechanism. Finally, the present challenges and future research directions concerning precious-metal-free acidic OER are comprehensively summarized and discussed in this review.

Electrophotocatalytic Hydroxymethylation of Azaarenes with Methanol

The merging of electrochemistry and photocatalysis allowed the required selectivity for the hydroxymethylation of functionalized azaarenes with methanol, including bioactive substrates. The two electrophotocatalytic protocols developed in this work address this transformation, using nontoxic and readily available reagents under mild reaction conditions with electricity as the only "sacrificial oxidant".

A four-step biosynthetic pathway involving C-3 oxidation-reduction reactions from cycloastragenol to astragaloside IV in Astragalus membranaceus

Astragaloside IV is a significant chemical component derived from the medicinal plant Astragalus membranaceus. Despite the characterization of several glycosyltransferases from A. membranaceus, the complete biosynthetic pathway of astragaloside IV has not been fully elucidated. In this study, we propose a biosynthetic pathway for astragaloside IV that involves a sequence of oxidation-reduction reactions. The biosynthesis pathway from cycloastragenol to astragaloside IV encompasses four key steps: C-3 oxidation, 6-O-glucosylation, C-3 reduction, and 3-O-xylosylation. We identified a hydroxysteroid dehydrogenase AmHSD1 from A. membranaceus. AmHSD1 catalyzes the C-3 oxidation of cycloastragenol, yielding cycloastragenol-3-one, and the C-3 reduction of cycloastragenol-3-one-6-O-glucoside, resulting in cycloastragenol-6-O-glucoside. Additionally, the glycosyltransferases AmGT8 and AmGT1, previously reported by our groups, were identified as catalyzing the 6-O-glucosylation and 3-O-xylosylation steps, respectively. Astragaloside IV was successfully synthesized in transient expression in Nicotiana benthamiana using the combination of AmHSD1, AmGT8 and AmGT1. These results support the proposed four-step biosynthetic pathway and suggest that AmHSD1 probably plays a crucial role in the biosynthesis of astragaloside IV within A. membranaceus.

Coupling High-Entropy Core with Rh Shell for Efficient pH-Universal Hydrogen Evolution

Constructing high-entropy alloys (HEAs) with core-shell (CS) nanostructure is efficient for enhancing catalytic activity. However, it is extremely challenging to incorporate the CS structure with HEAs. Herein, PtCoNiMoRh@Rh CS nanoparticles (PtCoNiMoRh@Rh) with ∼5.7 nm for pH-universal hydrogen evolution reaction (HER) are reported for the first time. The PtCoNiMoRh@Rh just require 9.1, 24.9, and 17.1 mV to achieve -10 mA cm-2 in acid, neutral, and alkaline electrolyte, and the corresponding mass activity are 5.8, 2.79, and 91.8 times higher than that of Rh/C. Comparing to PtCoNiMoRh nanoparticles, the PtCoNiMoRh@Rh exhibit excellent HER activity attributed to the decrease of Rh 4d especially 4d5/2 unoccupied state induced by the multi-active sites in HEA, as well as the synergistic effect in Rh shell and HEA core. Theorical calculation exhibits that Rh-dyz, dx2, and dxz orbitals experience a negative shift with shell thickness increasing. The HEAs with CS structure would facilitate the rational design of high-performance HEAs catalysts.

Selective hydrogenation of nitro compounds to amines by coupled redox reactions over a heterogeneous biocatalyst

Cleaner synthesis of amines remains a key challenge in organic chemistry because of their prevalence in pharmaceuticals, agrochemicals and synthetic building blocks. Here, we report a different paradigm for chemoselective hydrogenation of nitro compounds to amines, under mild, aqueous conditions. The hydrogenase enzyme releases electrons from H2 to a carbon black support which facilitates nitro-group reduction. For 30 nitroarenes we demonstrate full conversion (isolated yields 78 - 96%), with products including pharmaceuticals benzocaine, procainamide and mesalazine, and 4-aminophenol - precursor to paracetamol (acetaminophen). We also showcase gram-scale synthesis of procainamide with 90% isolated yield. We demonstrate potential for extension to aliphatic substrates. The catalyst is highly selective for reduction of the nitro group over other unsaturated bonds, tolerant to a wide range of functional groups, and exhibits excellent stability in reactions lasting up to 72 hours and full reusability over 5 cycles with a total turnover number over 1 million, indicating scope for direct translation to fine chemical manufacturing.

Research Progress on Elemental Mercury (Hg0) Removal in Flue Gas Using Non-Thermal Plasma Technology

Elemental mercury (Hg0) removal is a crucial target for mercury pollution control in flue gas. This article focuses on Hg0 removal in flue gas using corona discharge (CD) and dielectric barrier discharge (DBD) technologies, and provides a mechanistic perspective on the development and influencing factors of non-thermal plasma (NTP) technology for Hg0 removal. The influence factors include reactor configurations, power supplies, energy density, residence time, oxidation methods, gas composition, and the synergy between NTP and catalysis/adsorption, etc. This study reveals that the use of a pulsating electrical power supply significantly increases electron densities in both CD and DBD systems, thereby ensuring high energy efficiency and economic viability. Cl2 proves to be more effective than HCl as a chlorine source for Hg0 removal. NO significantly reduces Hg0 oxidation efficiency, while the effects of SO2 and H2O remain unclear. Energy density distribution is closely related to plasma devices, power supplies, and overall reactor configurations. Direct oxidation proves to be more effective than indirect oxidation for Hg0 removal. The combination of NTP with adsorption/catalysis technologies shows significantly better Hg0 removal efficiency compared to using NTP alone. This study can provide theoretical support for enhancing Hg0 removal mechanisms and optimizing process control parameters in industrial applications of NTP technology.

Boosting oxygen evolution reaction by FeNi hydroxide-organic framework electrocatalyst toward alkaline water electrolyzer

The oxygen evolution reaction plays a vital role in modern energy conversion and storage, and developing cost-efficient oxygen evolution reaction catalysts with industrially relevant activity and durability is highly desired but still challenging. Here, we report an efficient and durable FeNi hydroxide organic framework nanosheet array catalyst that competently affords long-term oxygen evolution reaction at industrial-grade current densities in alkaline electrolyte. The desirable high-intensity performance is attributed to three aspects as follows. First, two-dimensional nanosheet porous arrays with maximum specific surface facilitate mass/charge transfer to accommodate high-current-density catalysis. Second, in situ derived FeNi hydroxide motifs offer bimetallic synergistic catalysis centers with high intrinsic activity. Third, carboxyl ligands alleviate metal oxidation favorable for charge tolerability against peroxidation dissolution under strong polarization. As a result, this catalyst requires an overpotential of only 280 mV to deliver high current density up to 1 A/cm2 with long durability over 1000 h. Moreover, an alkaline water electrolyzer with this catalyst alternative demonstrates an increased economic effectiveness compared to commercial levels at present.

The Application of Flow Chemistry for the Synthesis of Alkyl Sodium Compounds and Their Transformations with Weinreb Amides and Carboxylic Acids

Herein, we describe the application of a flow system for the generation of a soluble organo sodium compound and the transformation of this primary nucleophile with various Weinreb amides for the synthesis of alkyl-aryl ketones. Thereafter, the generation of secondary sodium intermediates, such as benzylic sodium nucleophiles or ortho-metalated sodium nucleophiles from various carbon pre-nucleophiles, is described. These transformations generated more complex ketones, and in this investigation the key aspect was to identify factors for the chemoselective and regioselective C-H deprotonation of concurring sites within the starting material. Finally, the direct synthesis of ketones from carboxylic acids and the organo sodium compound is described, revealing interesting aspects regarding the nucleophilicity and basicity of the alkyl sodium reagent.

Anisotropic Superprotonic Conduction in a Layered Single-Component Hydrogen-Bonded Organic Framework with Multiple In-Plane Open Channels

Hydrogen-bonded organic frameworks (HOFs) are promising proton conductive materials because of their inherent and abundant hydrogen-bonding sites. However, most superprotonic-conductive HOFs are constructed from multiple components to enable favorable framework architectures and structural integrity. In this contribution, layered HOF-TPB-A3 with a single component is synthesized and exfoliated. The exfoliated nanoplates exhibited anisotropic superprotonic conduction, with in-plane proton conductivities reaching 1.34 × 10-2 S cm-1 at 296 K and 98% relative humidity (RH). This outperforms the previously reported single-component HOFs and is comparable with the state-of-the-art multiple-component HOFs. The high and anisotropic proton conductive properties can be attributed to the efficient proton transport along multiple open channels parallel to their basal planes. Moreover, an all-solid-state (ASS) proton rectifier device is demonstrated by combining HOF-TPB-A3 and a hydroxide ion-conducting layered double hydroxide (LDH). This work suggests that single-component HOFs with multiple open channels offer more opportunities as versatile platforms for proton conductors, making them promising candidates for conducting media in protonic devices.

Electrochemical Dehydrogenative [3 + 2]/[5 + 2] Annulation of N-Arylacrylamides with γ,σ-Unsaturated Malonates via Direct C(sp3)-H/C(sp2)-H Functionalization

Herein, we introduce an electrochemical dehydrogenative [3 + 2]/[5 + 2] annulation of easily available N-arylacrylamides with γ,σ-unsaturated malonates through C(sp3)-H/C(sp2)-H functionalization. The employment of inexpensive ferrocene as the redox catalyst allows access to diverse benzo[b]azepin-2-ones in moderate to excellent yields without stoichiometric oxidants. This protocol features broad substrate scope and excellent selectivity, and mechanistic studies indicated that the reaction proceeded through the oxidation of a C(sp3)-H bond to generate an alkyl radical, radical addition across the C═C bond, [3 + 2]/[5 + 2] annulations, and C(sp2)-H functionalization cascades.

Unleashing the Potential of Single-Atom Nanozymes: Catalysts for the Future

Single-atom nanozymes (SANs) have become a breakthrough in atomically precise catalysis, which relies on the catalytic active site formed by the single-atom itself. From this angle, SANs and their advantages compared to natural enzymes as well as spaces for their application are emphasized. The SANs have outstanding control over their catalytic activities; this is compared with bulk materials and natural enzymes. The structure of the SANs has very promising potential for the next generation of biosensing and biomedical devices and environmental remediation. Although their capabilities are high, difficulties still arise. The specificity, scalability, biosafety, and catalysis mechanisms raise additional issues that require further research. We build up a vision of the perspectives of the better implementation of SANs, which are designed for diagnostic purposes, improving industrial technologies, and creating new sustainable technologies in the food processing industry. AI and machine learning systems may clarify the structure-performance relationship of SANs for improved material and process selectivity. The future of SANs is very promising, and by addressing these challenges and leveraging advancements in artificial intelligence and materials science, SANs have the potential to become powerful tools for a sustainable future.

Photoredox/Copper Dual-Catalyzed Phosphorothiolation of Propargylic Derivatives for the Switchable Synthesis of S-Alkyl, S-Vinyl and S-Allenyl Phosphorothioates

Herein, we report a photoredox/copper dual-catalyzed selective phosphorothiolation of propargylic derivatives from easily accessible [P(O)SH] compounds. This reaction provides a general, mild and versatile procedure to synthesize a variety of synthetically useful S-alkyl, S-vinyl and S-allenyl phosphorothioates selectively from the same set of simple starting materials.

Closed-loop recyclable polymers: from monomer and polymer design to the polymerization-depolymerization cycle

The extensive utilization of plastic, as a symbol of modern technological society, has consumed enormous amounts of finite and non-renewable fossil resources and produced huge amounts of plastic wastes in the land or ocean, and thus recycling and reuse of the plastic wastes have great ecological and economic benefits. Closed-loop recyclable polymers with inherent recyclability can be readily depolymerized into monomers with high selectivity and purity and repolymerized into polymers with the same performance. They are deemed to be the next generation of recyclable polymers and have captured great and increasing attention from academia and industry. Herein, we provide an overview of readily closed-loop recyclable polymers based on monomer and polymer design and no-other-reactant-involved reversible ring-opening and addition polymerization reactions. The state-of-the-art of circular polymers is separately summarized and discussed based on different monomers, including lactones, thiolactones, cyclic carbonates, hindered olefins, cycloolefins, thermally labile olefin comonomers, cyclic disulfides, cyclic (dithio) acetals, lactams, Diels-Alder addition monomers, Michael addition monomers, anhydride-secondary amide monomers, and cyclic anhydride-aldehyde monomers, and polymers with activatable end groups. The polymerization and depolymerization mechanisms are clearly disclosed, and the evolution of the monomer structure, the polymerization and depolymerization conditions, the corresponding polymerization yield, molecular weight, performance of the polymers, monomer recovery, and depolymerization equipment are also systematically summarized and discussed. Furthermore, the challenges and future prospects are also highlighted.

Role of Interfacial Water Structure in the Electroreduction of NO over Cu2O

The electrochemical nitric oxide reduction reaction (NORR), which utilizes water as the sole hydrogen source, has the potential to facilitate ammonia production while concurrently mitigating pollutants. However, limited research has been dedicated to characterizing the structure of interfacial water due to the challenges associated with probing this intricate system, impeding the development of more efficient catalysts for the NORR process. Herein, the Cu2O microcrystals with distinct exposed facets, including {100}, {110}, and {111}, are employed for the model catalysts to investigate interfacial water structure and intermediate species in the NORR process. The results from shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) indicated that the NORR performance in 0.1 M Na2SO4 (with heavy water as the solvent) was positively correlated to the proportion of hydrated Na+ ion water. In addition, a sequence of intermediates from the NORR, including *NOH, *NH, *NH2, and *NH3, was detected by employing a combination of multiple in situ characterization methods. Furthermore, in conjunction with experimental results and theoretical calculations, we revealed the potential reaction pathway of NORR. This study offers novel insights into the NORR mechanism and valuable guidance for the design of high-performance catalysts for ammonia production.