Catalytic Mechanism Research Articles

In Situ Raman Study of Layered Double Hydroxide Catalysts for Water Oxidation to Hydrogen Evolution: Recent Progress and Future Perspectives

With the increasing global emphasis on green energy and sustainable development goals, the electrocatalytic oxygen evolution reaction (OER) is gradually becoming a crucial focus in research on water oxidation for hydrogen generation. However, its complicated reaction processes associated with its high energy barrier severely limit the efficiency of energy conversion. Recently, layered double hydroxide (LDH) has been considered as one of the most promising catalysts in alkaline media. Nonetheless, lacking a deep insight into the kinetic process of the electrocatalytic OER process is detrimental to the further optimization of LDH catalysts. Therefore, monitoring the catalytic reaction kinetic process via surface-sensitive in situ spectroscopy is especially important. In particular, the in situ Raman technique is capable of providing fingerprint information for surface species and intermediates in the operating environment. From the perspective of Raman spectroscopy, this paper provides an exhaustive overview of research progress in in situ Raman for the characterization of the catalytic mechanism of LDH catalysts, providing theoretical guidance for designing LDH materials. Finally, we present an incisive discussion on the challenges of the electrocatalytic in situ Raman technique and its future development trend.

Transition Metals Doped into g-C3N4 via N,O Coordination as Efficient Electrocatalysts for the Carbon Dioxide Reduction Reaction.

The electrochemical carbon dioxide reduction reaction (CO2RR) is a potential and efficient method that can directly convert CO2 into high-value-added chemicals under mild conditions. Owing to the exceptionally high activation barriers of CO2, catalysts play a pivotal role in CO2RR. In this study, the transition metal (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) is doped into g-C3N4 with a unique N,O-coordination environment, namely, TM-N1O2/g-C3N4. Herein, the catalytic performance and reaction mechanism for the CO2RR on TM-N1O2/g-C3N4 are systematically investigated by density functional theory methods. Especially, through the calculation of ΔG*H and ΔG*COOH/ΔG*OCHO, the catalysts with preference for the CO2RR over the hydrogen evolution reaction (HER) are selected for further study. Furthermore, Gibbs free energy computation results of each elementary step for the CO2RR on these catalysts indicate that Ti-N1O2/g-C3N4 has significant catalytic activity and selectivity for reducing CO2 to methanol (CH3OH) with the limiting potential (UL) of -0.55 V. Finally, through frontier molecular orbital theory and charge transfer analyses, the introduction of the O atoms illustrates that it is instrumental in regulating the electron distribution of the catalytic active site, thereby improving the catalytic performance. This work provides insight into the design of single-atom catalysts with unique coordination structures for the CO2RR.

Nanozymes: a bibliometrics review.

As novel multifunctional materials that merge enzyme-like capabilities with the distinctive traits of nanomaterials, nanozymes have made significant strides in interdisciplinary research areas spanning materials science, bioscience, and beyond. This article, for the first time, employed bibliometric methods to conduct an in-depth statistical analysis of the global nanozymes research and demonstrate research progress, hotspots and trends. Drawing on data from the Web of Science Core Collection database, we comprehensively retrieved the publications from 2004 to 2024. The burgeoning interest in nanozymes research across various nations indicated a growing and widespread trend. This article further systematically elaborated the enzyme-like activities, matrix, multifunctional properties, catalytic mechanisms and various applications of nanozymes, and the field encounters challenges. Despite notable progress, and requires deeper exploration guide the future research directions. This field harbors broad potential for future developments, promising to impact various aspects of technology and society.

Investigation of AMA Synthase from Pyrenophora teres f. teres 0–1 for the Synthesis of Aspergillomarasmine A Analogues and Non‐Canonical Amino Acids

AbstractThe fungal natural product aspergillomarasmine A (AMA) is an inhibitor of metallo‐β‐lactamases and a promising co‐drug candidate for reversing bacterial β‐lactam resistance. The biosynthesis of AMA from L‐Asp and O‐phospho‐L‐serine is catalyzed by AMA synthase, which possesses high synthetic potential for the biocatalytic preparation of AMA and related aminopolycarboxylic acids. Here, we identified and structurally characterized an AMA synthase from Pyrenophora teres f. teres 0–1 (PteAMAS). Crystallographic analysis revealed a unique homotetrameric fold and a highly hydrophilic active site, which supports the PLP‐dependent β‐replacement catalytic mechanism. Furthermore, we demonstrated the utility of PteAMAS for the biocatalytic synthesis of AMA and its analogues, achieving structural diversification of the APA1 moiety through a modular two‐enzyme system involving PteAMAS and a selective C−N lyase, namely EDDS lyase or 3‐methylaspartate ammonia lyase variant MAL−Q73 A. In addition, we exhibited the usefulness of PteAMAS for convenient synthesis of various S‐alkyl, ‐aryl, and ‐arylalkyl substituted L‐cysteines, which are valuable non‐canonical amino acids with broad pharmaceutical applications. The present study has not only provided the structural basis for catalysis and substrate recognition by PteAMAS, but also paved the way for biocatalytic preparation of structurally complex AMA analogues and various non‐canonical amino acids.

Catalytic Syntheses of Thiol-End-Functionalized ROMP Polymers.

Thiol-functionalized polymers have become a crucial class of materials due to their distinct chemical properties and versatile reactivity, leading to a broad spectrum of applications. Herein, we report the straightforward syntheses of a wide range of thiol-end-functionalized ring-opening metathesis polymerization (ROMP) polymers exploiting our previously reported catalytic ROMP mechanisms using suitable chain transfer agents. All the synthesized polymers were characterized via SEC, 1H NMR spectroscopy and MALDI-ToF mass spectrometry techniques. Furthermore, the existence of thiol groups on the polymer chains was verified through the well-established thiol coating reaction on gold nanoparticle surfaces. We believe this method of synthesizing thiol-end-functionalized ROMP polymers (using a reduced amount of ruthenium metal compared to conventional living ROMP) will be of great importance to materials science and biochemical research.

Advanced Preparation Methods and Biomedical Applications of Single-Atom Nanozymes.

Metal nanoparticles with inherent defects can harness biomolecules to catalyze reactions within living organisms, thereby accelerating the advancement of multifunctional diagnostic and therapeutic technologies. In the quest for superior catalytic efficiency and selectivity, atomically dispersed single-atom nanozymes (SANzymes) have garnered significant interest recently. This review concentrates on the development of SANzymes, addressing potential challenges such as fabrication strategies, surface engineering, and structural characteristics. Notably, we elucidate the catalytic mechanisms behind some key reactions to facilitate the biomedical application of SANzymes. The diverse biomedical uses of SANzymes including in cancer therapy, wound disinfection, biosensing, and oxidative stress cytoprotection are comprehensively summarized, revealing the link between material structure and catalytic performance. Lastly, we explore the future prospects of SANzymes in biomedical fields.

Natural Chiral Ligand Strategy: Metal-Catalyzed Reactions with Ligands Prepared from Amino Acids and Peptides

Amino acids and peptides are readily available biomolecules and can function as chiral ligands for transition metal catalysis. An example is the copper complex catalyzed 1,4-addition of dialkylzinc to acyclic enones, which employs peptide ligands. This review provides a dataset of amino acids and peptides reported in the literature proving to be effective ligands for metal-centered catalysts. Several parameters were highlighted, including amino acid combination, metal atoms, carboxyl and amino protecting groups, modification of natural amino acids, and the mechanism of catalysis. Along with analyzing physical-chemical properties, the SMILES representation for each amino acid and/or peptide was generated and made available online, providing an easy-to-use means of training machine learning models. This review offers an opportunity for the development of more efficient peptide ligands for enantioselective metal-centered catalysts. The available online dataset is a reliable manually curated table, it enables the benchmark for comparison of new terminal functional groups. Moreover, the review provides insight into the structures of the more successful peptide ligands and can be used as the foundation for the development of the next generation of peptide-based chiral ligands.

Interface-Engineered CuxO@Bi2MoO6 Heterojunctions to Inhibit Piezoelectric Screening Effect and Promote Double-Nanozyme Catalysis for Antibacterial Treatment.

Sonodynamic therapy is confronted with the low acoustic efficiency of sonosensitizers, and nanozymes are accompanied by intrinsic low catalytic activity. Herein, to increase the piezopotential of N-type piezoelectric semiconductors, the P-N heterojunction is designed to inhibit the piezoelectric screening effect (PSE) and increase electron utilization efficiency to enhance nanozyme activity. P-type CuxO nanoparticles are in situ grown on N-type piezoelectric Bi2MoO6 (BMO) nanoflakes (NFs) to construct heterostructured CuxO@BMO by interface engineering. CuxO deposition leads to lattice distortion of BMO NFs to improve piezoelectric response, and the strong interface electric field (IEF) suppresses PSE and increases piezopotential. The nonlocal piezopotential, local IEF, and glutathione (GSH) inoculation enhances electron-hole separation and increases peroxidase (POD)-like activity of BMO and GSH oxidase (GSHOx)-like activity of CuxO with high selectivity. The heterojunction formation causes the transfer and rearrangement of interface electrons, and the increased piezopotential accelerates electron transfer at interfaces with bacteria, thus increasing the production of reactive oxidative species and interfering with adenosine triphosphate synthesis. The heterostructured nanozymes produce abundant intracellular ·OH and achieve 4log magnitude reductions in viable bacteria and effective biofilm dispersion. This study elucidates integral mechanisms of nanozyme and acoustic catalysis and opens up a new way to synergize high piezopotential and nanozyme-catalyzed therapy.

Biological Characteristics of a Novel Bibenzyl Synthase (DoBS1) Gene from Dendrobium officinale Catalyzing Dihydroresveratrol Synthesis

Bibenzyl compounds are one of the most important bioactive components of natural medicine. However, Dendrobium officinale as a traditional herbal medicine is rich in bibenzyl compounds and performs functions such as acting as an antioxidant, inhibiting cancer cell growth, and assisting in neuro-protection. The biosynthesis of bibenzyl products is regulated by bibenzyl synthase (BBS). In this study, we have cloned the cDNA gene of the bibenzyl synthase (DoBS1) from D. officinale using PCR with degenerate primers, and we have identified a novel type III polyketide synthase (PKS) gene by phylogenetic analyses. In a series of perfect experiments, DoBS1 was expressed in Escherichia coli, purified and some catalytic properties of the recombinant protein were investigated. The molecular weight of the recombinant protein was verified to be approximately 42.7 kDa. An enzyme activity analysis indicated that the recombinant DoBS1-HisTag protein was capable of using 4-coumaryol-CoA and 3 malonyl-CoA as substrates for dihydroresveratrol (DHR) in vitro. The Vmax and Km of the recombinant protein for DHR were 3.57 ± 0.23 nmol·min−1·mg−1 and 0.30 ± 0.08 mmol, respectively. The present study provides further insights into the catalytic mechanism of the active site in the biosynthetic pathway for the catalytic production of dihydroresveratrol by bibenzylase in D. officinale. The results can be used to optimize a novel biosynthetic pathway for the industrial synthesis of DHR.

Insights into Catalytic Oxidative Reaction Mechanisms of Pentane on the Ru(0001) Surface

Insights into Catalytic Oxidative Reaction Mechanisms of Pentane on the Ru(0001) Surface

The Kinetics of Carbon-Carbon-Bond Formation in Metazoan Fatty Acid Synthase and its Impact on Product Fidelity.

Fatty acid synthase (FAS) multienzymes are responsible for de novo fatty acid biosynthesis and crucial in primary metabolism. Despite extensive research, the molecular details of the FAS catalytic mechanisms are still poorly understood. For example, the b-ketoacyl synthase (KS) catalyzes the fatty acid elongating carbon-carbon-bond formation, which is the key catalytic step in biosynthesis, but factors that determine the speed and accuracy of his reaction are still unclear. Here, we report enzyme kinetics of the KS-mediated carbon-carbon bond formation, enabled by a continuous fluorometric activity assay. We observe that the KS is likely rate-limiting to the fatty acid biosynthesis, its kinetics are adapted to the length of the bound fatty acyl chain, and that the KS is also responsible for the fidelity of biosynthesis by preventing intermediates from undergoing KS-mediated elongation. To provide mechanistic insight into KS selectivity, we performed computational molecular dynamics (MD) simulations. We identify positive cooperativity of the KS dimer, which we suggest to affect the conformational variability of the multienzyme. Advancing our knowledge about the KS molecular mechanism will pave the ground for engineering FAS for biotechnology applications and the design of new therapeutics targeting the fatty acid metabolism.

Structure of the yeast ceramide synthase.

Ceramides are essential lipids involved in forming complex sphingolipids and acting as signaling molecules. They result from the N-acylation of a sphingoid base and a CoA-activated fatty acid, a reaction catalyzed by the ceramide synthase (CerS) family of enzymes. Yet, the precise structural details and catalytic mechanisms of CerSs have remained elusive. Here we used cryo-electron microscopy single-particle analysis to unravel the structure of the yeast CerS complex in both an active and a fumonisin B1-inhibited state. Our results reveal the complex's architecture as a dimer of Lip1 subunits bound to the catalytic subunits Lag1 and Lac1. Each catalytic subunit forms a hydrophobic crevice connecting the cytosolic site with the intermembrane space. The active site, located centrally in the tunnel, was resolved in a substrate preloaded state, representing one intermediate in ceramide synthesis. Our data provide evidence for competitive binding of fumonisin B1 to the acyl-CoA-binding tunnel.

The Kinetics of Carbon‐Carbon‐Bond Formation in Metazoan Fatty Acid Synthase and its Impact on Product Fidelity

Fatty acid synthase (FAS) multienzymes are responsible for de novo fatty acid biosynthesis and crucial in primary metabolism. Despite extensive research, the molecular details of the FAS catalytic mechanisms are still poorly understood. For example, the b‐ketoacyl synthase (KS) catalyzes the fatty acid elongating carbon‐carbon‐bond formation, which is the key catalytic step in biosynthesis, but factors that determine the speed and accuracy of his reaction are still unclear. Here, we report enzyme kinetics of the KS‐mediated carbon‐carbon bond formation, enabled by a continuous fluorometric activity assay. We observe that the KS is likely rate‐limiting to the fatty acid biosynthesis, its kinetics are adapted to the length of the bound fatty acyl chain, and that the KS is also responsible for the fidelity of biosynthesis by preventing intermediates from undergoing KS‐mediated elongation. To provide mechanistic insight into KS selectivity, we performed computational molecular dynamics (MD) simulations. We identify positive cooperativity of the KS dimer, which we suggest to affect the conformational variability of the multienzyme. Advancing our knowledge about the KS molecular mechanism will pave the ground for engineering FAS for biotechnology applications and the design of new therapeutics targeting the fatty acid metabolism.

Classification and Summary of Photocatalytic Chemical Reactions Driven by Triplet‐Triplet Annihilation Upconversion

AbstractTriplet‐triplet annihilation upconversion (TTA‐UC) technology could convert low‐energy light into high‐energy light, and it is a very promising one of the upconversion technologies due to its non‐coherent excitation light, low required excitation optical power density and sensitizer/annihilator flexible adjustability. The application of TTA‐UC into photocatalysis could not only broaden the range of solar energy spectrum utilization, but also bring mild reaction conditions and higher product yields via avoiding the side reaction. However, the detailed catalytic mechanism of TTA‐UC is unclear. Therefore, in this review, we summarized and classified TTA‐UC photocatalytic chemical reactions in terms of mechanism.

Bayesian Learning Aided Theoretical Optimization of IrPdPtRhRu High Entropy Alloy Catalysts for the Hydrogen Evolution Reaction.

The complex compositional space of high entropy alloys (HEAs) has shown a great potential to reduce the cost and further increase the catalytic activity for hydrogen evolution reaction (HER) by compositional optimization. Without uncovering the specifics of the HER mechanism on a given HEA surface, it is unfeasible to apply compositional modifications to enhance the performance and save costs. In this work, a combination of density functional theory and Bayesian machine learning is used to demonstrate the unique catalytic mechanism of IrPdPtRhRu HEA catalysts for HER. At high coverage of underpotential-deposited hydrogen, a d-band investigation of the active sites of the HEA surface is conducted to elucidate the superior catalytic performance through electronic interactions between elements. At low coverage, a novel Bayesian learning with oversampling approach is then outlined to optimize the HEA composition for performance improvement and cost reduction. This approach proves more efficacious and efficient and yields higher-quality structures with less training set bias compared with neural-network optimization. The proposed HEA optimization theoretically outperforms benchmark Pt catalysts' overpotential by ≈40% at a 15% reduced synthesis cost comparing to the equiatomic ratio HEA.

Advancements in the Engineering Modification of Sucrose Phosphorylase

Sucrose phosphorylase (SPase) is a member of the glycoside hydrolase family 13, catalyzing the reversible phosphorolysis of sucrose to produce α–glucose–1–phosphate and exhibiting transglycosylation activity toward multiple substrates. Its wide substrate specificity enables the synthesis of various glycosides, which are broadly applied in food, cosmetics, and pharmaceuticals. However, the industrial application of SPase is constrained by its poor thermostability and limited transglycosylation activity. Therefore, current research focuses on enhancing the thermostability and transglycosylation activity of SPase through efficient engineering strategies based on its crystal structure and catalytic mechanism. This paper systematically reviews the crystal structure and catalytic mechanism of SPase, outlines the application of protein engineering and immobilization strategies in improving the thermostability of SPase, and analyzes how modifications at key amino acid sites affect the synthesis of typical glycosylation products. It also summarizes the limitations of SPase engineering modification strategies and explores the potential of diversified approaches for SPase modification, highlighting its broad application prospects in industrial production and laying a solid foundation for further advancements in SPase engineering modification and its industrial application.

Phase Reconstruction‐Assisted Electron‐Li+ Reservoirs Enable High‐Performance Li‐S Battery Operation Across Wide Temperature Range

AbstractLithium‐sulfur batteries (LSBs) are known as high energy density, but their performance deteriorates sharply under high/low‐temperature surroundings, due to the sluggish kinetics of sulfur redox conversion and Li+ transport. Herein, a catalytic strategy of phase reconstruction with abundant “electron‐Li+” reservoirs has been proposed to simultaneously regulate electron and Li+ exchange. As a demo, the 1T‐phase lithiation molybdenum disulfide grown on hollow carbon nitride (1T‐LixMoS2/HC3N4) is achieved via in situ electrochemical modulation, where the 1T‐LixMoS2 serves as an auxiliary “Li+ source” for facilitating Li+ transport and the HC3N4 acts as an electron donor for electronic supplier. From the theoretical calculations, experimental and post‐modern analyses, the relationship between the catalytic behaviors and mechanism of “electron‐Li+” reservoirs in accelerating the rate‐determining kinetics of sulfur species are deeply understood. Consequently, the cells with 1T‐LixMoS2/HC3N4/PP functional separator demonstrate excellent long‐term electrochemical performance and stabilize the areal capacity of 6 mAh cm−2 under 5.0 mg cm−2. Even exposed to robust surroundings from high (60 °C) to low (0 °C) temperatures, the optimized cells exhibit high‐capacity retention of 76.2% and 90.4% after 100 cycles, respectively, pointing out the potential application of catalysts with phase reconstruction‐assisted “electron‐Li+” reservoirs in LSBs.

Catalytic Production and Upgrading of Furfural: A Platform Compound

Furfural is a renewable platform compound that can be derived from lignocellulosic biomass. The highly functionalized molecular structure of furfural enables us to prepare a variety of high value-added chemicals, which will help realize biomass high-value utilization, and alleviate energy and environmental problems. This paper reviews the research progress on furfural production and upgrading to C5 chemicals from the catalyst perspective. The emphasis is placed on summarizing and refining the catalytic mechanism and in-depth analysis of available data. Specifically, the reaction mechanism of furfural production and upgrading is summarized firstly from the perspective of reaction pathways and reaction kinetics. Then, the available data are further processed to evaluate the actual reaction efficiency of different catalytic systems from multiple dimensions. Finally, based on statistical analysis, the challenges and opportunities of furfural-based research are proposed.

Enhancing Oxygen Reduction Reaction Electrocatalytic Performance of Nickel‐Nitrogen‐Carbon Catalysts through Coordination Environment Engineering†

Comprehensive SummarySingle‐atom catalysts (SACs) have attracted significant attention due to their high atomic utilization and tunable coordination environment. However, the catalytic mechanisms related to the active center and coordination environment remain unclear. In this study, we systematically investigated the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic activities of NiN4, NiN3, NiN3H2, NiN4X, NiN3X, and NiN3H2X (X denotes axial ligand) through density functional theory (DFT) calculations. This study unveils two distinct reaction pathways for ORR and OER, involving proton‐electron pairs adsorbed from both the solution and the catalyst surface. The overpotential is the key parameter to evaluate the catalytic performance when proton‐electron pairs are adsorbed from the solution. NiN3 and NiN3H2 show promise as pH‐universal bifunctional electrocatalysts for both ORR and OER. On the other hand, when proton‐electron pairs are adsorbed from the catalyst surface, the reaction energy barrier becomes the crucial metric for assessing catalytic activity. Our investigation reveals that NiN3H2 consistently exhibits optimal ORR activity across a wide pH range, regardless of the source of proton‐electron pair (solvent or catalyst surface).

Rational Design of Diatomic Active Sites for Elucidating Oxygen Evolution Reaction Performance Trends

AbstractDiatomic catalysts, especially those with heteronuclear active sites, have recently attracted significant attention for their advantages over single‐atom catalysts in reactions with relatively high energy barrier, e.g. oxygen evolution reaction. Rational design and synthesis of heteronuclear diatomic catalysts are of immense significance but have so far been plagued by the lack of a definitive correlation between structure and catalytic properties. Here, we report macrocyclic precursor constrained strategy to fabricate series of transition metal (MT, Ni, Co, Fe, Mn, or Cu)‐noble (MN, Ir or Ru) centers in carbon material. One notable performance trend is observed in the order of Cu−MN<Mn−MN<Fe−MN<MN<Co−MN<Ni−MN. Meanwhile, the pathway has been not altered, still following the traditional adsorption reaction mechanism. The effect of the MT atoms on the performances could possibly originate from the distinct adsorption/desorption behaviors of key intermediates (i.e. *OH, *O and/or *OOH), strongly implying that ΔG*OOH–ΔG*OH could be used as the performance descriptor. We believe that our work provides useful strategy for synthesis of diatomic active sites with sole coordination configuration and varied composition, and in‐depth insight to their catalytic mechanism, which could be used for further optimization of diatomic catalysts towards oxygen electrocatalysis.