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High entropy materials (HEM) have been attracting much attention as emerging catalysts for electrochemical water splitting. HEM catalysts have unique properties such as an interesting cocktail effect, broad design space, customizable electronic structure, and excellent entropy stabilization effect compared with single-digit catalysts. This paper provides a comprehensive overview of the use of HEM as a catalyst for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and water splitting. HEM design strategies including phase structure modulation, defect engineering, electrode configuration engineering, and computational aids are discussed to develop HEM catalysts with high performance and stability. In particular, the importance of density functional theory, high-throughput screening techniques, and machine learning for the discovery and design of HEM catalysts is emphasized. Finally, the challenges and imminent difficulties are prospected, and the corresponding strategies to deal with these challenges are put forward to promote the development of HEM catalysts in the field of electrochemical water splitting. [ABSTRACT FROM AUTHOR]

The development of efficient non-noble metal electrocatalysts for the oxygen evolution reaction (OER) under acidic conditions remains a critical challenge. Herein, we report a N-doped carbonaceous component-engineered Co3O4 (NCEC) catalyst synthesized via the sol-gel method. Dopamine hydrochloride (DA)-derived nitrogen-doped carbonaceous components were found to boost the OER performance of Co3O4. The optimized catalyst can reach an overpotential as low as 330 mV in 1 M H2SO4 at a current density of 10 mA cm-2 and maintains a good long-term stability of 60 hours. In particular, we found that the thermodynamic overpotential was inversely proportional to the content of oxidized N and pyridinic N, whereas it was directly proportional to the pyrrolic-N content. Our experiments and density functional theory (DFT) calculations confirm that the optimized catalyst exhibits enhanced charge transfer and the oxidized N species on Co3O4 is responsible for the high catalytic activity. Our study suggests that the performance of NCEC in acidic media can be further optimized by enhancing the content of oxidized N species. [ABSTRACT FROM AUTHOR]

This study employs density functional theory at the SMD/B3LYP-D3/6-311+G(2d,p),def2-TZVPP//SMD/B3LYP-D3/6-31G(d),SDD level of theory to explore the mechanistic details of O2 generation from tBuOOH, using H218O as the solvent, in the presence of the Mn(II) catalyst [Mn2(mcbpen)2(H2O)2]2+. Since this chemistry was reported to occur through the reaction of Mn(III)(μ-O)Mn(IV)–O˙ with water, we first revaluated this proposal and found that it occurs with an activation barrier greater than 36 kcal mol−1, ruling out the functioning of such a dimer as the active catalyst. Experimental evidence has shown that the oxidation of [Mn2(mcbpen)2(H2O)2]2+ by tBuOOH in H218O produces the Mn(IV) species [Mn(18O)(mcbpen)]+. Our investigations revealed a plausible mechanism for this observation in which [Mn (18O)(mcbpen)]+ acts as the active catalyst, generating the tert-butyl peroxyl radical (tBuOO˙) through its reaction with tBuOOH. In this proposed mechanism, the O–O bond is formed through the interaction of tBuOO˙ with another [Mn(18O)(mcbpen)]+, finally leading to the formation of the 16O＝18O product. Our findings underscore the pivotal role of [Mn(18O)(mcbpen)]+ in both generating the active species tBuOO˙ and consuming it to produce 16O＝18O. With activation barriers as low as about 9 kcal mol−1, these elementary steps highlight the feasibility of our proposed mechanism. Moreover, this mechanism elucidates why, experimentally, one of the oxygen atoms in the released O2 comes from water, while the other originates from tBuOOH. This research broadens our understanding of high oxidation state manganese chemistry, setting the stage for the development of more efficient Mn-based catalysts, aimed at improving processes in both renewable energy and synthetic chemistry. [ABSTRACT FROM AUTHOR]

Biomass provides a promising source of carbon for obtaining environment-friendly carbon materials, but obtaining heteroatom-doped carbon materials (HDCMs) from biomass directly by a green method still remains challenging. This study successfully synthesized nitrogen and phosphorus co-doped porous carbon materials (Y-NPC) by the simple in situ pyrolysis of renewable yeast mixed with water from 800 to 950 °C. Various characterization methods show that nitrogen and phosphorus are doped into the carbon skeleton and mainly exist in the forms of graphite-N, pyridine-N, C–P, P–N, and P–O states. The catalyst Y-NPC-900 °C with a 3D hierarchical porous structure and high P–N content exhibited superior nitro hydrogenation performance and reaction stability using molecular hydrogen and hydrazine hydrate as hydrogen sources under mild conditions. Density functional theory (DFT) calculations and experiments attributed the exceptional catalytic performance to hydrogen activation and the good adsorption ability of substrates over N, P co-doped carbon (NPC). Therefore, this research proposes an eco-friendly and simple synthesis strategy for in situ N, P co-doping metal-free carbon catalysts derived from biomass, showing the significance of N, P co-doping and single N- or P-monodoping in the charge distribution of carbon materials. [ABSTRACT FROM AUTHOR]

This density functional theory (DFT) study explores the efficacy of cooperative catalytic systems in enabling the ionic hydrogenation of N2 with H2, leading to NH3 formation. A set of N-heterocyclic carbene-based pincer tungsten/molybdenum metal complexes of the form [(PCP)M1(H)2] (M1 = W/Mo) were chosen to bind N2 at the respective metal centres. Simultaneously, cationic rhodium/iridium complexes of type [Cp*M2{2-(2-pyridyl)phenyl}(CH3CN)]+ (Cp* = C5(CH3)5 and M2 = Rh/Ir), are employed as cooperative coordination partners for heterolytic H2 splitting. The stepwise transfer of protons and hydrides to the bound N2 and intermediate NxHy units results in the formation of NH3. Interestingly, the calculated results reveal an encouraging low range of energy spans ranging from ∼30 to 42 kcal mol−1 depending on different combinations of ligands and metal complexes. The optimal combination of pincer ligand and metal center allowed for an energy span of unprecedented 29.7 kcal mol−1 demonstrating significant potential for molecular catalysts for the N2/H2 reaction system. While exploring obvious potential off-cycle reactions leading to catalyst deactivation, the computed results indicate that no increase in energy span would need to be expected. [ABSTRACT FROM AUTHOR]

The quantitative structure-property relationship (QSPR) of constrained geometry catalysts (CGCs) has been analyzed by combining density functional theory (DFT) and multivariate linear regression (MLR). QSPR models for determining the reaction energy barriers of ethylene and 1-octene and molecular descriptors were established and validated with a testing set. At the initiation stage, the quaternary QSPR models for ethylene and 1-octene feature R² values of 0.90 and 0.82, respectively, while the corresponding leave-one-out Q² values for ethylene and 1-octene are determined to be 0.82 and 0.69. Using the generated QSPR models, the electronic effect was proven to be more critical for determining the energy barriers of ethylene and 1-octene insertion processes. At the propagation stage, the quaternary QSPR models for ethylene and 1-octene feature R² values of 0.97 and 0.96, respectively, while the corresponding leave-one-out Q² values for ethylene and 1-octene are determined to be 0.93. Particularly, the impact of the steric effect on the energy barriers of ethylene and 1-octene insertion is more pronounced. Furthermore, the correlation between the corresponding energy barriers and experimental activities with three series of CGCs was discussed, which revealed that theoretical calculations are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

The design of low-cost and high-performance bifunctional catalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is of great significance for overall water splitting. Herein, RuNi single atom alloy (SAA) decorated on reduced graphene oxide (RuNi@rGO) was synthesized by a facile strategy for use as a bifunctional HER/OER catalyst. The as-obtained RuNi@rGO catalyst exhibits outstanding electrocatalytic activities with an ultralow overpotential for the HER (15 mV) and the OER (240 mV) at a current density of 10 mA cm−2. Density functional theory (DFT) calculations demonstrate that the introduction of Ru single atoms can evidently change the electron distribution and coordination environment around Ni, and reduce the intermediate's adsorption free energy of RuNi@rGO, thus facilitating the HER/OER catalytic rate. Moreover, when used as the cathode and anode of a two-electrode system, the RuNi@rGO-based water splitting device exhibits a low potential of 1.52 V at a current density of 10 mA cm−2, as well as a high faradaic efficiency almost up to 100%, making RuNi@rGO bifunctional electrocatalysts attractive for energy storage and conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption energies of CO 2 on the surface oxygen vacancies of different crystalline In 2 O 3 were calculated using DFT. • The effect of the spatial distributions of two active components on the CO 2 hydrogenation to aromatics was studied. • The acidity of catalyst under different spatial distributions was studied through NH 3 -TPD. In tandem catalysts, not only good synergy between the two active components is required, but also the precise control of the spatial distribution between the two active components of metal oxides and zeolite is crucial for the migration and conversion of reaction intermediates in the direct conversion of CO 2 to hydrocarbons. The correlation between the metal and the acidic site of zeolite has traditionally been simplified as "the closer, the better". However, it should be noted that this principle only holds true for a portion of tandem catalysts. Therefore, this paper studied the effect of different crystalline In 2 O 3 (cubic phase, hexagonal phase, and mixed cubic/hexagonal phase) and sheet HZSM-5 zeolite tandem catalysts on the activity of CO 2 hydrogenation reaction under different spatial distribution. The generalized gradient approximation (GGA) of density functional theory (DFT) were used to simulate the adsorption energy of CO 2 by oxygen vacancy on c-In 2 O 3 (1 1 1) and h-In 2 O 3 (1 0 4) planes, it was found that O v1 on c-In 2 O 3 (1 1 1) and O v4 on h-In 2 O 3 (1 0 4) had the strongest adsorption energy for CO 2. In addition, it has been observed that the proximity of the two active components (e.g., during mortar mixing) results in decreased catalytic performance. This is due to the migration of metal In, which neutralizes the acid sites of zeolites and leads to inefficient conversion of methanol reaction intermediates to aromatics. As a result, CO 2 conversion and aromatic selectivity are decreased. [ABSTRACT FROM AUTHOR]

Copper-based catalysts have demonstrated notable efficacy in facilitating methanol conversion and hydrogen yield at low temperatures. Given the straightforward and cost-effective nature of the process, further investigation into this area is merited. This article provides a summary of the progress made in the development of copper-based catalysts for hydrogen production through methanol steam reforming. The catalytic performance of conventional Cu/ZnO/Al 2 O 3 catalysts can be exceeded by utilizing specific catalyst formulations and preparation procedures, which are characterized by their intricate structural and chemical properties. The studies about MSR mechanism have also been integrated. The realm of DFT research encompasses an examination of the monatomic systems, which have garnered significant attention in contemporary times. Furthermore, this paper presented potential avenues for future research on copper-based catalysts in the context of MSR. We believe that the forthcoming research will concentrate on the design, preparation, and molecular mechanism of copper-based catalysts that exhibit high stability, high activity, and low CO selectivity. [Display omitted] • Various copper-based catalysts for MSR are reviewed. • Research hotspots are given via disassembling the components of catalysts. • Synthesis processes for outstanding catalytic performances are underlined. • The MSR mechanisms are reviewed in detail. • DFT Studies considering experimental results are emphasized. [ABSTRACT FROM AUTHOR]

[Display omitted] • The main N 2 O removal methods and their catalysts are elucidated. • The previous mechanism studies using DFT are revealed. • The characteristics and improvement strategies of various catalysts are summarized. • The future development of more efficient N 2 O removal catalyst is proposed. • It furnishes theoretical basis and data support for exploring N 2 O removal catalysts. With the increasing global warming, the control of nitrous oxide (N 2 O) emissions in various fields has become urgent. Direct catalytic decomposition is currently the most widely used technology to reduce N 2 O emissions from the nitric acid industry. Selective catalytic reduction (SCR), which can utilize unburned NH 3 from engine exhaust as a reductant, is the most promising technology for reducing N 2 O emissions from ammonia-fueled engines. Increasing demands on the operating temperature window, O 2 /H 2 O/NO resistance, and hydrothermal stability of catalysts have stimulated the development of novel catalytic N 2 O removal catalysts. This review first summarizes the N 2 O generation mechanism, comprehensive N 2 O catalytic removal reaction mechanism and O 2 /H 2 O/NO inhibition mechanism, and then provides a comprehensive overview of the related catalysts, including Ru- and Rh-based precious metal catalysts, Cu- and Co-based non-precious metal catalysts, and Fe- and Cu-based molecular sieve catalysts, focusing on direct catalytic decomposition of N 2 O and N 2 O-SCR. Effective strategies for various catalysts to improve the acidity, redox cycling, and toxicity resistance of the catalysts through modification, creation of novel nanostructures, and exposure of specific crystalline surfaces are summarized, and the challenges and opportunities they face are presented. In addition, this paper summarizes some other methods for catalytic removal of N 2 O and develops a detailed description for the synergistic removal of N 2 O and NO x. Finally, this review provides some suggestions for future research directions. It is hoped that this review will provide a theoretical basis for the optimal preparation of catalysts to bridge the gap between catalyst performance and practical needs, and help to realize the commercial application of efficient catalysts in the near future. [ABSTRACT FROM AUTHOR]

• Optimized pathway for the production of methyl acetate as by-product in the gas-phase synthesis of vinyl acetate from ethylene. • Adsorption properties of species on PdAu(100) surface during methyl acetate generation. • The combination of density functional theory and kinetic Monte Carlo method. Methyl acetate is a byproduct that is difficult to completely remove in the gas-phase process of producing vinyl acetate from ethylene. High-quality vinyl acetate products require stringent control of the methyl acetate content. However, studies on the mechanism of methyl acetate formation have not been reported, which constrains the modification of catalysts to reduce its formation. This paper presents a comprehensive study on the generation mechanism of methyl acetate during the ethylene-based vinyl acetate synthesis process over PdAu catalysts, utilizing a combination of DFT (Density Functional Theory) and kMC (kinetic Monte Carlo) simulations. The reaction network for the formation of methyl acetate on PdAu catalysts was constructed. Initially, DFT calculations were employed to investigate the adsorption properties of relevant species on the PdAu(100) surface. The results indicate that surface species preferentially adsorb at the Pd-Au bridge sites, diagonal Pd-Pd hollows, and diagonal Pd-Au hollows on the PdAu(100) catalyst, with a stronger interaction between the Pd atoms and the adsorbed species. Subsequently, DFT calculations were performed to identify the optimal pathways for the generation of methyl acetate on PdAu(100). Based on the kinetic parameters obtained from DFT calculations, kMC simulations were conducted to stimulate the generation process of methyl acetate. The results demonstrate that the dominant pathway for the formation of methyl acetate during the ethylene-based vinyl acetate synthesis over PdAu(100) is through CH 2 CH 2 * + O * → CH 2 CH * + H * → CH 3 CH * → CH 3 * + CH * ( CH * + H * → CH 2 * + H * → CH 3 *) → CH 3 * + CH 3 COO * → CH 3 COOCH 3 *. The reaction between CH 3 COO* and CH 3 * to form methyl acetate is identified as the rate-determining step, with an energy barrier of 1.75 eV and an exothermic reaction heat of −0.53 eV. [Display omitted] [ABSTRACT FROM AUTHOR]

Dual-atom site catalysts with the adjacent metal atomic sites can cooperatively catalyze oxygen reduction reaction (ORR), showing great potential in ORR field. Herein, the ORR activity and mechanism of a supported metal dual-atom site catalyst M2-DAC (M is 3d transition metal) is explored thoroughly by density functional theory methods. By calculating Ed of M2-DAC, all structures are thermodynamically stable and are used for subsequent studies. Considering the adsorption of O2, total 6 kinds of M2-DAC are identified as potential candidate materials for catalyzing ORR due to their moderate adsorption of O2. The binding energy of ORR species and the change of Gibbs free energy in each step of ORR are calculated, and Co2-DAC exhibits notable catalytic activity (ηORR = 0.39 V). Moreover, the charge analysis of Co2-DAC shows that the ORR activity of the catalyst mainly comes from the metal atom and the O atoms coordinated with the metal atoms. [ABSTRACT FROM AUTHOR]

The electrocatalytic nitrogen reduction reaction (NRR) for synthesizing ammonia holds promise as an alternative to the traditional high-energy-consuming Haber–Bosch method. Rational and accurate catalyst design is needed to overcome the challenge of activating N2 and to suppress the competitive hydrogen evolution reaction (HER). Single-atom catalysts have garnered widespread attention due to their 100% atom utilization efficiency and unique catalytic performance. In this context, we constructed theoretical models of metal single-atom catalysts supported on titanate nanosheets (M-TiNS). Initially, density functional theory (DFT) was employed to screen 12 single-atom catalysts for NRR- and HER-related barriers, leading to the identification of the theoretically optimal NRR catalyst, Ru-TiNS. Subsequently, experimental synthesis of the Ru-TiNS single-atom catalyst was successfully achieved, exhibiting excellent performance in catalyzing NRR, with the highest NH3 yield rate reaching 15.19 μmol mgcat−1 h−1 and a Faradaic efficiency (FE) of 15.3%. The combination of experimental results and theoretical calculations demonstrated the efficient catalytic ability of Ru sites, validating the effectiveness of the constructed theoretical screening process and providing a theoretical foundation for the design of efficient NRR catalysts. [ABSTRACT FROM AUTHOR]

Li-O2 batteries are considered a highly promising energy storage solution. However, their practical implementation is hindered by the sluggish kinetics of the oxygen reduction (ORR) and oxygen evolution (OER) reactions at cathodes during discharging and charging, respectively. In this work, we investigated the catalytic performance of Wn+1Cn and Wn+1CnO2 MXenes (n = 1, 2, and 3) as cathodes for Li-O2 batteries using first principles calculations. Both Wn+1Cn and Wn+1CnO2 MXenes show high conductivity, and their conductivity is further enhanced with increasing atomic layers, as reflected by the elevated density of states at the Fermi level. The oxygen functionalization can change the electronic properties of WC MXenes from the electrophilic W surface of Wn+1Cn to the nucleophilic O surface of Wn+1CnO2, which is beneficial for the activation of the Li-O bond, and thus promotes the Li+ deintercalation during the charge–discharge process. On both Wn+1Cn and Wn+1CnO2, the rate-determining step (RDS) of ORR is the formation of the (Li2O)2* product, while the RDS of OER is the LiO2* decomposition. The overpotentials of ORR and OER are positively linearly correlated with the adsorption energy of the RDS LixO2* intermediates. By lowering the energy band center, the oxygen functionalization and increasing atomic layers can effectively reduce the adsorption strength of the LixO2* intermediates, thereby reducing the ORR and OER overpotentials. The W4C3O2 MXene shows immense potential as a cathode catalyst for Li-O2 batteries due to its outstanding conductivity and super-low ORR, OER, and total overpotentials (0.25, 0.38, and 0.63 V). [ABSTRACT FROM AUTHOR]

To satisfy the need for catalyst materials with high activity, selectivity, and stability for energy conversion, material design and discovery guided by theoretical insights are a necessity. In the past decades, the rise in theoretical investigations into the properties of catalyst materials, reaction mechanisms, and catalyst design principles has shed light on the catalysis field. Quantitative structure–activity relationships have been developed through incorporating spectroscopic simulations, electronic structure calculations, and reaction mechanistic studies. In this review, we report the state-of-the-art computational approaches to catalyst materials characterization for supported single-atom and cluster catalysts utilizing spectroscopic simulations, i.e., XANES simulation, and material properties investigation via electronic-structure calculations. Furthermore, approaches regarding reaction mechanisms, focusing on active site heterogeneity, are also discussed. [ABSTRACT FROM AUTHOR]

The absence of efficient and durable catalysts for oxygen evolution reaction (OER) is the main obstacle to hydrogen production through water splitting in an acidic electrolyte. Here, we report a controllable synthesis method of surface IrO x with changing Au/Ir compositions by constructing a range of sub-10-nm-sized core-shell nanocatalysts composed of an Au core and Au x Ir1−x alloy shell. In particular, Au@Au0.43Ir0.57 exhibits 4.5 times higher intrinsic OER activity than that of the commercial Ir/C. Synchrotron X-ray-based spectroscopies, electron microscopy and density functional theory calculations revealed a balanced binding of reaction intermediates with enhanced activity. The water-splitting cell using a load of 0.02 mgIr/cm2 of Au@Au0.43Ir0.57 as both anode and cathode can reach 10 mA/cm2 at 1.52 V and maintain activity for at least 194 h, which is better than the cell using the commercial couple Ir/C‖Pt/C (1.63 V, 0.2 h). [ABSTRACT FROM AUTHOR]

[Display omitted] • Descriptor of ethylene conversion and selectivity (E ads, C2H2 - E ads, C2H4), calculations show that the energy barrier difference between Ni-M is greater than Ni. • Excellent geometric and electronic structures of Ni-M allow ethylene to be weakly adsorbed on the surface through π bonds. • Charge density results of C 2 H 4 * suggest that the adsorption of ethylene was weakened due to the transfer of charge from Fe and Co atoms to Ni atoms. • The energy barrier of ethylene desorbed is less than that of hydrogenation, so the desorbed of ethylene is greater than the hydrogenation, ensuring the reaction selectivity. Nickel-based bimetallic catalysts exhibit excellent ethylene selectivity in acetylene hydrogenation reactions. However, the rational design and control of the interaction between active adsorbates and catalyst surfaces still remains a significant challenge. In this paper, the introduction of the second metals Fe, Co, Mn, and Mo dilutes the catalyst surface and alters the electronic properties of Ni. As a result of the geometric and electronic dual modulation between the bimetals, ethylene is adsorbed on the catalyst surface through weak π-bonds, which accelerates the desorption of ethylene. In addition, alloying a second metal in Ni significantly lowers the desorption energy of ethylene compared to the hydrogenation barrier, which improves the selectivity of the reaction, and the experimental findings further confirm the validity of the calculations. This work offering a new strategy to the development Ni-based bimetallic catalysts by modulating the strength of adsorbed species on the catalyst surface to attain superior catalytic performance in hydrogenation reactions. [ABSTRACT FROM AUTHOR]

• Secondary and tertiary carbamates are prepared in high efficiency in an unprecedentive strategy. • Active transition metal-functionalized MOFs are synthesized via an in situ -grown protocolunder solvent-free mechanochemical conditions. • Both aminesand aniline are well tolerated. The solvent-free synthesis of MOF represents a promising and environmentally benign protocol. This paper outlines a green one-pot mechanochemical method for the synthesizing of UiO-66 in the absence of solvent, along with the implantation of three different metals (Cu, Ni, and Pd) into the defect sites. The materials have proven to be effective catalysts in the transformation between azidocarbonate and amines/anilines in moderate to excellent isolated yields (up to 94%), exhibiting better advantages compared with the exiting methodologies. More interestingly, Cu and Ni exhibited very good catalytic performance towards primary and secondary amines, respectively. It also should be noted that high yield was still observed after six cycles. Our work presents a novel and straightforward strategy for the preparation of secondary and tertiary carbamates in an unprecedented fashion, greatly enriched the toolbox for the synthetic community. Moreover, the combination of experimental studies and density functional theory (DFT) calculations gave more insight and evidence for the mechanism. Accompanied by the advantages of the effective and recyclable catalyst, the broad substrate scope, good functional group tolerance, and excellent reaction yields made the established method attractive in heterogeneous catalysis and the carbamates synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A system containing NiCe-based MOF catalyst was designed for HDO of vanillin. • Highly selective HDO of lignin derived vanillin to biofuel was achieved. • Metallic acid sites and oxygen vacancies enhanced HDO performance. • Ethanol was used as hydrogen donor solvent for the catalytic system. • 3Ni-Ce/C catalyst exhibited excellent stability after four recycling runs. Exploring an advanced catalytic strategy for the high value utilization of lignin derived chemicals into value-added aromatics has attracted tremendous sights for green manufacturing. In this paper, a series of bifunctional 3D rod-shaped mesoporous NiCe metal–organic framework catalysts coupling with hydrogen-donner solvent were reported for the hydrodeoxygenation of vanillin to obtain 2-methoxy-4-methylphenol. Under the optimal conditions, 3Ni-Ce/C catalyst realized the highest conversion of vanillin (>95.0 %) and selectivity of 81.4 % in the absence of additional hydrogen pressure. The characterization results indicated that the interaction of metallic Ni and CeO 2 promoted the generation of Ni-CeO 2-x interface and oxygen vacancies (Ov), which could efficiently adsorb and activate aldehyde group of vanillin to obtain reactive intermediates. And then metallic Ni sites activated the hydrogen-donner solvent to form adsorbed H atoms, which then spilled over to the adjacent Ov to stabilized reactive intermediates. Whereafter, bifunctional 3D rod-shaped mesoporous NiCe metal–organic framework catalysts achieved the hydrodeoxygenation upgrading of vanillin to obtain 2-methoxy-4-methylphenol. Density functional theory (DFT) calculations further revealed that the synergistic effect of Ni-CeO 2 and oxygen vacancies promoted the activation and dissociation of aldehyde group bond in vanillin, enhanced the ability of protonation hydrogenolysis. Additionally, 3Ni-Ce/C catalyst displayed robust activity for no less than four recycles, which provided a feasible method for the build of simultaneous utilization of lignin derivates to value-added fuels and chemicals. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) computational studies of a series of single-atom catalysts (SACs). Geometry of M1/PTA (M1 = Mn, Fe, Co, Ru, Rh, Pd, Os, Ir, Pt; phosphor tungstic acid (PTA) = [PW12O40]3−), different spin multi-gravity, adsorption site screening, metal–support interactions and M1/PTA SACs catalyzed catalytic cycle for O2 and olefin oxidation. Studies have shown that the most likely anchoring sites for isolated single atoms on M1/PTA SACs are quadruple holes on the surface of the PTA support. According to the PTA-Os bond, all single Os-based MOs are responsible for the non-bonding nature. It greatly maintains the catalytic activity of the PTA-loaded single-atom catalyst. Among these M1/PTA SACs, Os/PTA and Ru/PTA SACs have better activation ability for oxygen molecules, because the catalyst can produce dissociative adsorption of O2 and greatly weaken the bond energy of the O–O bond. Finally, the mechanism of Os/PTA SAC catalyzing the epoxidation of O2 and propylene is proposed. The reaction process of Os/PTA SAC activated O2 with propylene epoxidation, the relative energies, structures of intermediates and transition states were analyzed, and the reaction energy barrier of the rate determination step (RDS) was 24.48 kcal·mol−1 for the reaction between the second oxygen atom and C3H6. This indicates the reaction is thermodynamically and kinetically feasible and provides an important and reliable theoretical basis for the experimental synthesis and application. [ABSTRACT FROM AUTHOR]

Catalytic oxidation is used to control carbon monoxide (CO) emissions from industrial exhaust. In this study, a mesoporous silica material, KCC-1, was synthesized and used as a carrier with a high specific surface area to confine active component FeOx nanoparticles (NPs), and the CO catalytic oxidation performance of x%Fe@KCC-1 catalysts (x represents the mass loading of Fe) was studied. The experimental results showed that due to its large specific surface area and abundant mesopores, the FeOx NPs were highly dispersed on the surface of the KCC-1 carrier. The particle size of FeOx was very small, resulting in strong interactions between FeOx NPs and KCC-1, which enhanced the catalytic oxidation reaction on the catalyst. The FeOx loading improved the CO adsorption capability of the catalyst, which facilitated the catalytic oxidation of CO, with the 7%Fe@KCC-1 catalyst achieving 100% CO conversion at 160 °C. The CO catalytic removal mechanism was investigated by a combination of in-situ DRIFTS and DFT calculations. This study advances scientific understanding of the application potential of nano-catalysts in important oxidation reactions and provides valuable insights into the development of efficient CO oxidation catalysts. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) production by the electrochemical 2‐electron oxygen reduction reaction (2e− ORR) is a promising alternative to the energy‐intensive anthraquinone process, and single‐atom electrocatalysts show the unique capability of high selectivity toward 2e− ORR against the 4e− one. The extremely low surface density of the single‐atom sites and the inflexibility in manipulating their geometric/electronic configurations, however, compromise the H2O2 yield and impede further performance enhancement. Herein, we construct a family of multiatom catalysts (MACs), on which two or three single atoms are closely coordinated to form high‐density active sites that are versatile in their atomic configurations for optimal adsorption of essential *OOH species. Among them, the Cox–Ni MAC presents excellent electrocatalytic performance for 2e− ORR, in terms of its exceptionally high H2O2 yield in acidic electrolytes (28.96 mol L−1 gcat.−1 h−1) and high selectivity under acidic to neutral conditions in a wide potential region (>80%, 0–0.7 V). Operando X‐ray absorption and density functional theory analyses jointly unveil its unique trimetallic Co2NiN8 configuration, which efficiently induces an appropriate Ni–d orbital filling and modulates the *OOH adsorption, together boosting the electrocatalytic 2e− ORR capability. This work thus provides a new MAC strategy for tuning the geometric/electronic structure of active sites for 2e− ORR and other potential electrochemical processes. [ABSTRACT FROM AUTHOR]