Hydrogenation Of Intermediates Research Articles

Operando Unveiling of Hydrogen Spillover Mechanisms on Tungsten Oxide Surfaces.

Hydrogen spillover is an important process in catalytic hydrogenation reactions, facilitating H2 activation and modulating surface chemistry of reducible oxide catalysts. This study focuses on the operando unveiling of platinum-induced hydrogen spillover on monoclinic tungsten trioxide (γ-WO3), employing ambient pressure X-ray photoelectron spectroscopy, density functional theory calculations and microkinetic modeling to investigate the dynamic evolution of surface states at varied temperatures. At room temperature, hydrogen spillover results in the formation of W5+ and hydrogen intermediates (hydroxyl species and adsorbed water), facilitated by Pt metal clusters. With increasing temperature, water desorption, reverse hydrogen spillover and surface-to-bulk diffusion of hydrogen atoms compete with each other, leading initially to reoxidation and then further reduction of W atoms in the near-surface. The combined experimental results and simulations provide a comprehensive understanding of the mechanisms underlying hydrogen interaction with reducible metal oxides, lending insights of relevance to the design of enhanced hydrogenation catalysts.

Engineering Lattice Dislocations of TiO2 Support of PdZn-ZnO Dual-Site Catalysts to Boost CO2 Hydrogenation to Methanol.

CO2 hydrogenation to methanol using green hydrogen derived from renewable resources provides a promising method for sustainable carbon cycle but suffers from high selectivity towards byproduct CO. Here, we develop an efficient PdZn-ZnO/TiO2 catalyst by engineering lattice dislocation structures of TiO2 support. We discover that this modification orders irregularly arranged atoms in TiO2 to stabilize crystal lattice, and consequently weakens electronic interactions with supported active phases. It facilitates the transformation of metallic Pd into PdZn alloy, effectively suppressing CO production through inhibiting the reverse water-gas shift reaction mediated by the carboxylate pathway on Pd0 sites. Moreover, it enables the efficient transfer of hydrogen species via hydrogen spillover from PdZn alloy to ZnO for compensating the poor hydrogen dissociation ability of ZnO, thereby creating both more oxygen vacancies essential for CO2 activation and a hydroxyl-rich environment conducive to hydrogenation of intermediates. These collective modifications on PdZn-ZnO dual sites synergistically induce the propensity of the formate pathway for methanol synthesis. Consequently, compared to the unmodified catalyst, our as-designed catalyst increases methanol selectivity from 64.2 to 80.0 %, reduces CO selectivity from 35.0 to 19.8 %, and achieves an impressive methanol space-time yield of 9028.0 mgMeOH gPd+Zn -1 h-1 at a similar CO2 conversion (~8.0 %).

Engineering lattice dislocations of TiO2 support of PdZn‐ZnO dual‐site catalysts to boost CO2 hydrogenation to methanol

CO2 hydrogenation to methanol using green hydrogen derived from renewable resources provides a promising method for sustainable carbon cycle but suffers from high selectivity towards byproduct CO. Here, we develop an efficient PdZn‐ZnO/TiO2 catalyst by engineering lattice dislocation structures of TiO2 support. We discover that this modification orders irregularly arranged atoms in TiO2 to stabilize crystal lattice, and consequently weakens electronic interactions with supported active phases. It facilitates the transformation of metallic Pd into PdZn alloy, effectively suppressing CO production through inhibiting the reverse water‐gas shift reaction mediated by the carboxylate pathway on Pd0 sites. Moreover, it enables the efficient transfer of hydrogen species via hydrogen spillover from PdZn alloy to ZnO for compensating the poor hydrogen dissociation ability of ZnO, thereby creating both more oxygen vacancies essential for CO2 activation and a hydroxyl‐rich environment conducive to hydrogenation of intermediates. These collective modifications on PdZn‐ZnO dual sites synergistically induce the propensity of the formate pathway for methanol synthesis. Consequently, compared to the unmodified catalyst, our as‐designed catalyst increases methanol selectivity from 64.2 to 80.0%, reduces CO selectivity from 35.0 to 19.8%, and achieves an impressive methanol space‐time yield of 9028.0 mgMeOH gPd+Zn‐1 h‐1 at a similar CO2 conversion (~8.0%).

Controllable Active Intermediate in CO2 Hydrogenation Enabling Highly Selective N,N-Dimethylformamide Synthesis via N-Formylation.

N,N-Dimethylformamide (DMF) is a widely used solvent, and its green and low-carbon synthesis methods are in high demand. Herein, we report a new approach for DMF synthesis using a continuous flow reaction system with a fixed-bed reactor and a ZnO-TiO2 solid solution catalyst. This catalyst effectively utilizes CO2, H2, and dimethylamine (DMA) as feedstocks, demonstrating performance with 99% DMF selectivity and single-pass DMA conversion approaching thermodynamic equilibrium. Moreover, the catalyst demonstrates good stability, with no signs of deactivation over 1000 h of continuous operation. The key to superior activity lies in the synergetic effect of the Zn and Ti sites, which facilitates the formation of active formate species. These species act as crucial intermediates, reacting with DMA to produce DMF. Importantly, the slow hydrogenation kinetics of the formate species prevent the formation of CH2O* species, thereby suppressing the formation of the undesired byproduct, trimethylamine. This work underscores the potential of kinetically controlling active intermediates in CO2 hydrogenation to prepare high-value-added chemicals by coupling them to platform molecules. It presents a promising strategy for the efficient utilization of CO2 resources and offers a valuable solution for large-scale DMF synthesis.

Constructing Lewis Acid-Base Pairs to Boost Electrocatalytic Hydrogenation of p-Nitrobenzoic Acid to Valuable p-Aminobenzoic Acid Using Water as the Hydrogen Source.

Electrocatalytic hydrogenation of toxic nitrobenzene to value-added aniline is of great significance in addressing the issues of energy crisis and environmental pollution. However, it is a considerable challenging and crucial to develop highly efficient and earth-abundant transition metal-based electrocatalysts with superior durability for the electro-hydrogenation of nitrobenzene due to the competitive hydrogen evolution reaction (HER). In this work, a facile approach is designed and introduced to constructing an integrated self-supported heterostructured Co1- xNix(OH)(CO3)/Al(OH)3 nanoarrays (CoNiCH/Al(OH)3) for the electrocatalytic reduction of nitrobenzoic acid (PNBA) to p-aminobenzoic acid (PABA) and its electrocatalytic mechanism for PNBA reduction is investigated. This unique Lewis acid-base pairs with abundant oxygen vacancies (OVs) can effectively regulate the adsorption energy of PNBA and active hydrogen intermediates, facilitate the proton-coupled electrocatalytic reduction process, leading to the high activity and selectivity for PNBA to PABA. The optimal CoNiCH/Al(OH)3-0.5 exhibits outstanding performance for the electrocatalytic hydrogenation of PNBA to PABA with a yield of 92%, selectivity of 95% and Faraday efficiency (FE) of 92% at -0.545V (vs reversible hydrogen electrode, RHE) under 0.1m phosphate buffered solution (PBS) neutral electrolyte. Besides, it can maintain a high electrocatalytic activity for at least eight electrocatalytic cycle-test.

A five‐fold twin structure copper for enhanced electrocatalytic nitrogen reduction to sustainable ammonia

AbstractUtilizing N₂ from the air and water for the electrocatalytic nitrogen reduction reaction shows promise for NH₃ synthesis under mild conditions. However, the chemical stability of N₂ and the thermodynamic limitations of NH₃ synthesis hinder its effectiveness. Herein, we integrated a specially designed Cu nanowire catalyst with a five‐fold twin structure (T‐CuNW) into an electrocatalytic system, combining electrocatalytic nitrogen reduction with nonthermal plasma‐assisted N₂ activation. This work achieved an NH₃ yield of 45 mg·mgcat.−1·h−1 and a Faradaic efficiency of over 95% at −0.5 V versus RHE after a 90‐h stability test. In situ characterization revealed that the T‐CuNW's twin structure plays a crucial role for the generation of a large quantity of Hads, essential for the hydrogenation of nitrate intermediates, particularly nitrite (NO₂−). This enhanced hydrogenation process significantly contributes to the high performance of the ammonia synthesis system.

MXene-supported 2D bimetallic chalcogenide electrocatalyst: Enhanced electrochemical seawater splitting

Hydrogen energy holds immense potential for revolutionizing modern energy technologies. Seawater electrolysis is a promising strategy for hydrogen production; however, the lack of effective electrodes limits its widespread application. Therefore, developing high-performance, cost-effective catalysts for water splitting is essential for sustainable energy conversion. In this context, we report a novel hybrid bimetallic selenide (CoMoSe2) and MXene (Ti3C2Tx) electrocatalyst, which exhibits remarkable catalytic performance for seawater electrolysis. The CoMoSe2@Ti3C2Tx electrocatalyst demonstrates outstanding catalytic capabilities, achieving overpotentials of 82 mV for hydrogen evolution reaction (HER) and 329 mV for oxygen evolution reaction (OER) at a current density of 10 mA cm⁻2 in alkaline conditions. The Tafel slope values are 124 mV dec⁻1 for hydrogen evolution and 69 mV dec⁻1 for oxygen evolution, outperforming their individual components. The enhanced bifunctional catalytic performance of the hybrid catalyst is attributed to the synergistic effect of Mo atoms within the CoSe2 crystal structure, which modifies the electronic structure and lowers the chemisorption energies of hydrogen and oxygen intermediates. The abundance of oxygen vacancies provides more reactive active sites and improves electrical conductivity. Additionally, the CoMoSe2@Ti3C2Tx composite has demonstrated remarkable bifunctional electrocatalytic performance for seawater splitting, achieving 10 mA cm⁻2 at overpotentials of 161 mV for HER and 354 mV for OER in alkaline seawater. The Volmer-Heyrovsky mechanism drives the remarkable long-term stability of the catalyst. This novel approach contributes to sustainable energy solutions by providing a fresh avenue for the development of effective catalysts to produce hydrogen from seawater.

Nanoporous nonprecious multi-metal alloys as multisite electrocatalysts for efficient overall water splitting

Developing robust nonprecious metal-based electrocatalysts toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for hydrogen production via electrochemical water splitting. Herein, the NiFeCoCuTi alloy is described as a multisite electrocatalyst for highly effective hydrogen and oxygen evolution in alkaline environments. This is achieved by utilizing heterogeneous atoms on the surface that exhibit distinct adsorption behaviors for hydrogen and hydroxyl, thereby accelerating the dissociation of water and mediating the adsorption of hydrogen intermediates required for molecule formation. The monolithic nanoporous multi-metal NiFeCoCuTi alloy electrode displays remarkable alkaline HER and OER electrocatalysis, exhibiting low overpotentials of 48.7 and 264.2 mV, respectively, to deliver a current density of 10 mA cm−2. Furthermore, it demonstrates exceptional stability for over 100 h in 1 M KOH electrolyte. The exceptional qualities of nanoporous NiFeCoCuTi alloy electrodes make them a highly desirable option for utilization as the cathode and anode material in water electrolysis, which produces hydrogen. They also imply that this is the optimal platform for the development of multisite electrocatalysts.

Constructing Dense CoRu-CoMoO4 Heterointerfaces with Electron Redistribution for Synergistically Boosted Alkaline Electrocatalytic Water Splitting.

Constructing metal alloys/metal oxides heterostructured electrocatalysts with abundant and strongly coupling interfaces is vital yet challenging for practical electrocatalytic water splitting. Herein, CoRu nanoalloys uniformly anchored on CoMoO4 nanosheet heterostructured electrocatalyst (CoRu-CoMoO4/NF) are synthesized via a self-templated strategy by simply annealing of Ru-etched CoMoO4/NF precursor in a reduction atmosphere. The dense and robustly coupled interface not only provides abundant active sites for water splitting but also strengthens the charge transfer efficiency. Furthermore, the theoretical calculations unveil that the strong electronic interaction at CoRu-CoMoO4 interface can induce an interfacial electron redistribution and reduce the energetic barriers for the hydrogen and oxygen intermediates, thereby accelerating the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics. The resultant catalyst only requires the overpotentials of 49mV for HER and 209mV for OER at 10mAcm-2. Moreover, the constructed CoRu-CoMoO4||CoRu-CoMoO4 two-electrode cell achieves a cell voltage of 1.54V at 10mAcm-2, outperforming the benchmark Pt/C||IrO2. This work explores an avenue for the rational design of heterostructured electrocatalysts with abundant interfaces for practical water-splitting electrocatalysis.

Operando Investigation of the Solid Electrolyte Interface in the Electrochemical Lithium-Mediated Ammonia Synthesis

Ammonia plays a crucial role in fertilizer production, but its conventional synthesis via the Haber-Bosch process is marked by high energy consumption, centralization, and dependence on non-renewable resources, resulting in considerable carbon emissions. In contrast, the lithium-mediated electrochemical nitrogen reduction reaction (Li-NRR) emerges as an innovative solution, enabling ammonia synthesis at room pressure and temperature with the potential for renewable energy integration [1]. This approach also promotes the decentralization of ammonia manufacturing. Within the Li-NRR framework, metallic lithium undergoes electrochemical deposition in an organic electrolyte and is believed to subsequently interact with inert nitrogen molecules, facilitating its protonation and the formation of ammonia [2].In recent years, significant research efforts aimed at boosting the selectivity and efficiency of the Li-NRR through the modification of electrolyte salt composition and concentration, alongside the implementation of potential cycling techniques [3-4]. These advancements are often attributed to alterations in the structure and composition of the solid electrolyte interface (SEI) formed on the cathode's surface, analogous to phenomena observed in lithium-ion batteries. Nonetheless, our current understanding of SEI properties primarily stems from ex situ analyses of the catalysts and the bulk electrolyte, leaving the behavior of this interface under reaction conditions largely unexplored.In this study, our aim is to deepen our understanding of the SEI's structure and composition under Li-NRR reaction conditions. Therefore, we employed cutting-edge operando spectroscopic techniques, such as surface-enhanced Raman spectroscopy, to closely examine the electrochemical interface during operational conditions. Taking inspiration from our expertise in lithium batteries we studied various electrolyte compositions and concentrations, including LiClO4 and LiFSI in tetrahydrofuran and ethanol to correlate the SEI’s properties with the performance of Li-NRR for ammonia production [5]. This approach enabled us to monitor the early stages of lithium plating and the subsequent formation and evolution of the SEI. Consequently, we could observe the changes and stability of various inorganic and organic SEI species, influenced by the initial composition of the electrolyte, and link them to the ammonia performance. Importantly, our investigations revealed ethanol's critical role in forming the organic SEI layer. By tracking nitrogen and hydrogen intermediates, we could further establish their correlation to the Li-NRR's efficiency, underscoring the competition with the hydrogen evolution reaction (HER). The mechanistic insights garnered from this study will aid in fine-tuning and enhancing the electrolyte composition for the improvement of Li-NRR in industrial applications.

A Generalizable Electrochemical Platform for Batch-to-Continuous Transitions

Greenhouse gas emissions from the chemical industry are massive, amounting by some estimates to ~5% of the global total.1 Chemical manufacturing is also very difficult to decarbonize due to the dual use of hydrocarbons as a fuel and feedstock.2 Hence, to eliminate anthropogenic greenhouse gas emissions the chemical industry must undergo a fundamental change in how it uses energy and materials. Organic electrosynthesis has seen a significant increase in research interest as an alternative to the traditional thermochemical approach for chemical production. Electrochemical transformations offer a direct path to electrification via driving reactions with electricity rather than heat. This means that as grid electricity decarbonizes, so too do electrochemical processes. Moreover, environmentally hazardous chemical oxidants, such as fuming acid mixtures, and reductants like methane-derived hydrogen, can be replaced by oxygen and hydrogen intermediates generated on the surface of electrodes through water electrolysis.Despite the potential advantages for broad implementation of industrial electrosynthesis, research interest falls primarily on the production of commodity chemicals, such as CO2 valorization and nitrogen fixation. Successful implementation of these schemes could certainly drive a significant amount of global decarbonization, but this focus has also led to underdevelopment of other electrochemical reactions that could be implemented today with significant emissions reductions. The focus of this presentation is on these types of under-explored organic electrosynthetic transformations that are specifically relevant to specialty chemical manufacturing.The electrochemical literature has many examples of batchwise electrosynthesis of specialty chemicals.3 Scaling these processes to industrially relevant levels very often benefits from the development of continuous reactor systems. Although continuous electrosynthetic reactors have made extensive progress, there does not yet exist a well- developed and standardized set of methods, reactor architectures, and design principles for these types of cells. This lack of standardization stands as a significant impediment to adoption, especially in commercial settings. To address this knowledge gap, our lab is researching and designing a generalizable, modular electrochemical reactor to aid the transition from batch to continuous processing.This presentation will detail our recent work to determine the key differentiating characteristics of electrochemical reactions to design a modular and easily reconfigurable platform. Eight electrochemical reactions of various electrolyte composition and phase relationships were chosen as a basis to develop the reactor platform. The relevant design criteria for reactor design encompassed considerations of: (a) the composition of the electrolyte, including pH, reactant/product phase, material compatibility; (b) the electrode structure and functionalization, to be tuned to the intended reaction; and (c) the requirement of a divider, such as a porous separator or ion exchange membrane. By studying these and literature examples of successful batch-to-continuous transitions, we determined that reactors aimed at maximizing electrode-electrolyte contact converge toward a filter-press style. Next, we used these characteristics to design and fabricate a single reconfigurable filter press cell designed to accomplish each of the eight reactions of interest. Through its design and materials of construction, this cell is capable of handling a wide range of pH, any geometry of compressible or plate electrodes, and can be operated with or without a separator. Finally, we validated this platform by demonstrating the ability to generate reaction products with performance criteria that match or exceed those from an analogous batch reactor configuration. This validation also leads to several improvements to be made on this basic design, which will be incorporated into future iterations.References(1) Gabrielli, P.; Rosa, L.; Gazzani, M.; Meys, R.; Bardow, A.; Mazzotti, M.; Sansavini, G. Net-Zero Emissions Chemical Industry in a World of Limited Resources. One Earth 2023, 6 (6), 682–704. https://doi.org/10.1016/j.oneear.2023.05.006.(2) Gross, S. The Challenge of Decarbonizing Heavy Industry, 2021. https://www.brookings.edu/wp-content/uploads/2021/06/FP_20210623_industrial_gross_v2.pdf.(3) Li, Y.; Dana, S.; Ackermann, L. Recent Advances in Organic Electrochemical Functionalizations for Specialty Chemicals. Curr. Opin. Electrochem. 2023, 40, 101312. https://doi.org/10.1016/j.coelec.2023.101312.

Controlling the microenvironment by introducing dual metal atoms into ZIF-L to enhance hydrogen evolution activity

In this study, we introduce an efficient strategy to enhance the electrocatalytic performance of ZIF-L by injecting dual metal atoms, specifically Co and Cu, using a facile hydrothermal reaction method. The optimized Co,Cu-ZIF-L composites showed exceptional hydrogen evolution activities with overpotentials of 70 and 145 mV under 10 and 50 mA cm−2 in alkaline media. The Co,Cu-ZIF-L composites also displayed excellent cycling stability (∼ 90 h) for hydrogen evolution. The enhanced electrocatalytic performance is attributed to the dual metal atoms, which not only introduce abundant active sites but also improve the structural integrity and catalytic kinetics by regulating the catalytic microenvironment. Density functional theory calculations further support that the injection of Co and Cu atoms into the ZIF-L optimizes the free adsorption energy of hydrogen intermediates, accelerating HER kinetics. This work confirms that injecting highly conductive metal atom into MOFs to regulate the catalytic microenvironment is a potential route to significantly increase the electrocatalytic activity of MOFs.

Synergistic effects of Co single atoms and Co nanoparticles for electrocatalytic nitrate-to-ammonium conversion in strongly acidic wastewater

Efficient ammonium (NH4+) production from strongly acidic wastewater through electrocatalytic nitrate reduction reaction (NO3RR) holds promise, yet faces challenges due to hydrogen evolution competition and catalyst corrosion. This work reports a novel catalyst (i.e., CoSA-CoNP@N-CNA/CC), which consists of carbon cloth (CC) supporting a nitrogen-doped carbon nanotube array (N-CNA) that contains atomically dispersed Co single atoms (CoSA) and Co nanoparticles (CoNP), achieving exceptional NO3−-to-NH4+ conversion at pH 1. The resulting cathode produces NH4+ at a rate of 0.275 mmol h−1 cm−2 with a Faradaic efficiency of 95.6 %, without concurrent NO2− production at −0.6 V (vs. RHE). The study reveals that the synergy between individual Co atoms and encapsulated Co nanoparticles facilitates electron transfer, hindering hydrogen adsorption, enhancing NO3− adsorption and activation, and reducing the energy barrier for the rate-determining step involving intermediate *NO hydrogenation. Validation with real acidic samples underscores the exceptional capability of CoSA-CoNP@N-CNA/CC for NH4+ recovery via NO3RR.

Unconventional Hexagonal Close-Packed High-Entropy Alloy Surfaces Synergistically Accelerate Alkaline Hydrogen Evolution.

Accelerating the alkaline hydrogen evolution reaction (HER), which involves the slow cleavage of HO-H bonds and the adsorption/desorption of hydrogen (H*) and hydroxyl (OH*) intermediates, requires developing catalysts with optimal binding strengths for these intermediates. Here, the unconventional hexagonal close-packed (HCP) high-entropy alloy (HEA) atomic layers are prepared composed of five platinum-group metals to enhance the alkaline HER synergistically. The breakthrough is made by layer-by-layer heteroepitaxial deposition of subnanometer RuRhPdPtIr HEA layers on the HCP Ru seeds, despite the thermodynamic stability of Rh, Pd, Pt, and Ir in a face-centered cubic (FCC) structure except for Ru. The synchrotron X-ray absorption spectroscopy (XAS) confirms the atomic mixing and coordination environment of HCP RuRhPdPtIr HEA. Most importantly, they exhibit notable improvements in both electrocatalytic activity and durability for the HER in an alkaline environment, as compared to their FCC RuRhPdPtIr counterparts. Electrochemical measurements, operando XAS analysis, and density functional theory unveil that the binding strengths of H* and OH* intermediates on the active Pt and Ir sites can be weakened and strengthened to a moderate level, respectively, by mixing non-active Ru, Rh, and Pd atoms with Pt and Ir atoms within the HCP HEA with strong synergistic electronic effects.

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p-d Orbital Hybridization Effect with Ru.

Topological defects are inevitable existence in carbon-based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under-explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon-rings is probed by constructing pentagonal ring-rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p-d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron-deficient Ru species leads to a notable negative shift in d-band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm-2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm-2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p‐d Orbital Hybridization Effect with Ru

AbstractTopological defects are inevitable existence in carbon‐based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under‐explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon‐rings is probed by constructing pentagonal ring‐rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p‐d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron‐deficient Ru species leads to a notable negative shift in d‐band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm−2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm−2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

Operando Stable Palladium Hydride Nanoclusters Anchored on Tungsten Carbides Mediate Reverse Hydrogen Spillover for Hydrogen Evolution

AbstractProton exchange membrane (PEM) electrolysis holds great promise for green hydrogen production, but suffering from high loading of platinum‐group metals (PGM) for large‐scale deployment. Anchoring PGM‐based materials on supports can not only improve the atomic utilization of active sites but also enhance the intrinsic activity. However, in practical PEM electrolysis, it is still challenging to mediate hydrogen adsorption/desorption pathways with high coverage of hydrogen intermediates over catalyst surface. Here, operando generated stable palladium (Pd) hydride nanoclusters anchored on tungsten carbide (WCx) supports were constructed for hydrogen evolution in PEM electrolysis. Under PEM operando conditions, hydrogen intercalation induces formation of Pd hydrides (PdHx) featuring weakened hydrogen binding energy (HBE), thus triggering reverse hydrogen spillover from WCx (strong HBE) supports to PdHx sites, which have been evidenced by operando characterizations, electrochemical results and theoretical studies. This PdHx‐WCx material can be directly utilized as cathode electrocatalysts in PEM electrolysis with ultralow Pd loading of 0.022 mg cm−2, delivering the current density of 1 A cm−2 at the cell voltage of ~1.66 V and continuously running for 200 hours without obvious degradation. This innovative strategy via tuning the operando characteristics to mediate reverse hydrogen spillover provide new insights for designing high‐performance supported PGM‐based electrocatalysts.

MXene quantum dots-Co(OH)2 heterojunction stimulated Co2+δ sites for boosted alkaline hydrogen evolution

Persevering structural stability of the active species after phase reconfiguration poses a key challenge for various sustainable catalytic systems. In this study, we construct a robust β-Co(OH)2 electrocatalyst via self-adaptive coordination of MXene quantum dots (MQDs) during phase transition from the Co2(OH)3Cl precursor to β-Co(OH)2 (MQDs/β-Co(OH)2/Co foam). The heterojunction induced the excellent electron transfer, causing the lattice strain of β-Co(OH)2, and the accumulated electrons at the MQDs end regulated the electronic density of Co sites (Co2+δ), reversing the structural instability of β-Co(OH)2 within the applied reduction potential range. Furthermore, density functional theory calculation confirms the role of well-matched heterogeneous interfaces in HER. The result shows the high-valance Co2+δ sites promote adsorption and dissociation of H2O, increasing proton supply and accelerating reaction rate. Concurrently, MQDs facilitate the adsorption of hydrogen intermediates and H2 generation. Our architected catalyst exhibited exceptional alkaline hydrogen evolution reactions (HERs) performance (91 mV@10 mA cm−2) and superior stability outperforms most reported β-Co(OH) 2-based catalysts. Our work demonstrates the efficacy of MQDs as co-catalysts in enhancing the activity and structural stability of catalysts.

Built-in electric field-driven electron transfer behavior at Ru-RuP2 heterointerface fosters efficient and CO-resilient alkaline hydrogen oxidation

Exploiting a cost-effective electrocatalyst for hydrogen oxidation reaction (HOR) with high-performance and CO poisoning resistance is essential for the widespread application of alkaline anion exchange membrane fuel cells (AEMFCs). Herein, we craft a unique Ru-RuP2 heterostructure within hollow mesoporous carbon sphere (Ru-RuP2@C) using phosphide-controlled phase-transition approach. Benefiting from the interfacial electron transfer from RuP2 to Ru, the Ru-RuP2@C electrocatalyst exhibits impressive HOR performance with a mass activity of 2.87 mA μgRu−1. Notably, Ru-RuP2@C demonstrates strong tolerance to 1000 ppm CO, a capability lacking in PtRu/C and Pt/C. When serves as an anode catalyst for AEMFC, it achieves a peak power density of 521 mW cm−2, comparable to Pt/C. Experimental and theoretical analyses reveal that the built-in electric field, resulting from work function differences, creates an asymmetric charge distribution that modulates the d-band center of Ru-RuP2@C. This optimizes the adsorption strength of hydrogen and hydroxide intermediates, thereby accelerating HOR catalytic kinetics.

New Insights for High-Throughput CO2 Hydrogenation to High-Quality Fuel.

In the case of CO2 thermal-catalytic hydrogenation, highly selective olefin generation and subsequent olefin secondary reactions to fuel hydrocarbons in an ultra-short residence time is a huge challenge, especially under industrially feasible conditions. Here, we report a pioneering synthetic process that achieves selective production of high-volume commercial gasoline with the assistance of fast response mechanism. In situ experiments and DFT calculations demonstrate that the designed NaFeGaZr presents exceptional carbiding prowess, and swiftly forms carbides even at extremely brief gas residence times, facilitating olefin production. The created successive hollow zeolite HZSM-5 further reinforces aromatization of olefin diffused from NaFeGaZr via optimized mass transfer in the hollow channel of zeolite. Benefiting from its rapid response mechanism within the multifunctional catalytic system, this catalyst effectively prevents the excessive hydrogenation of intermediates and controls the swift conversion of intermediates into aromatics, even in high-throughput settings. This enables a rapid one-step synthesis of high-quality gasoline-range hydrocarbons without any post-treatment, with high commercial product compatibility and space-time yield up to 0.9 kggasoline ⋅ kgcat -1 ⋅ h-1. These findings from the current work can provide a shed for the preparation of efficient catalysts and in-depth understanding of C1 catalysis in industrial level.