Activity For Oxidation Reaction Research Articles

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

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

Theoretical study of adsorption properties and CO oxidation reaction on surfaces of higher tungsten boride

Most modern catalysts are based on precious metals and rear-earth elements, making some of organic synthesis reactions economically insolvent. Density functional theory calculations are used here to describe several differently oriented surfaces of the higher tungsten boride WB5-x, together with their catalytic activity for the CO oxidation reaction. Based on our findings, WB5-x appears to be an efficient alternative catalyst for CO oxidation. Calculated surface energies allow the use of the Wulff construction to determine the equilibrium shape of WB5-x particles. It is found that the (010) and (101) facets terminated by boron and tungsten, respectively, are the most exposed surfaces for which the adsorption of different gaseous agents (CO, CO2, H2, N2, O2, NO, NO2, H2O, NH3, SO2) is evaluated to reveal promising prospects for applications. CO oxidation on B-rich (010) and W-rich (101) surfaces is further investigated by analyzing the charge redistribution during the adsorption of CO and O2 molecules. It is found that CO oxidation has relatively low energy barriers. The implications of the present results, the effects of WB5-x on CO oxidation and potential application in the automotive, chemical, and mining industries are discussed.

Ni-Pt-Pd ternary alloy nanoparticles supported on carboxyl-modified carbon nanotubes as highly efficient catalyst for methanol and ethanol electrooxidation

Pt-based catalysts are currently the most efficient anode catalysts in alcohol fuel cells. However, their widespread commercialization is hindered by their high cost. In this study, a straightforward method was employed to deposit Ni-Pt-Pd ternary alloy nanoparticles onto carboxyl-modified multi-walled carbon nanotubes (CNTs) and subsequently annealed the synthesized catalysts at different temperatures to adjust the surface composition and alloying degree. The Ni-Pt-Pd alloy exhibits a synergistic effect between Pt and Ni. The presence of Ni effectively modulates the d-band center of Pt, thereby enhancing the electrochemical performance of for alcohol oxidation. The synergistic effect of Pt-Pd alloy is harnessed to enhance both catalytic activity and stability of the catalyst for oxidation of methanol or ethanol. Density functional theory (DFT) calculations demonstrated that alloying Pt with Pd and Ni effectively reduced the Gibbs free energy during EOR and MOR reactions. The resulting catalysts, denoted as Ni6Pt6Pd6 NPs/CNTs-M2, exhibited exceptional catalytic oxidation performance for both ethanol and methanol. Specifically, their electrochemical mass activity for ethanol oxidation reaction (EOR) reached 2345 mA mg-1Pt+Pd, which was 15.5-fold and 2.56-fold higher than that of commercial Pt/C and Pd/C catalysts respectively. Moreover, their mass activity for methanol oxidation reaction (MOR) was measured at 2995 mA mg-1Pt+Pd, which was 8.2-fold and 5.3-fold higher than that of Pt/C and Pd/C catalysts respectively.

Study of Se-based microgel catalyst for heterophase benzaldehyde oxidation

Benzaldehyde was oxidized with hydrogen peroxide in the heterophase system with different ratios of benzene and water using selenium-based catalysts. For the reaction, which was carried out in the ratio of benzene:water = 4:1, Se-microgel proved to be a highly active colloidal catalyst and allowed to achieve 94.1 % yield of benzoic acid at 60 °C. The synthesized Se-modified microgel demonstrates exceptional catalytic activity in oxidation reactions at the interface in various heterophase systems at different temperatures.

Boosting borohydride oxidation kinetics by manipulating hydrogen evolution and oxidation through octahedral Pt–Ni/C for high-performance direct borohydride fuel cells

Direct borohydride fuel cells (DBFCs) outperform the other direct liquid fuel cells by a higher open circuit voltage and energy density. However, their benign performance and efficiency are highly dependent on high-performance anode catalysts. This study delves into the enhancement of borohydride oxidation reaction (BOR) kinetics through an octahedral Pt–Ni/C catalyst. The Pt(111) facets of the catalyst exhibit a combination of abundant active sites exposed for BOR and the inherent ability to suppress hydrolysis reaction. Furthermore, the synergistic incorporation of Ni modifies the electronic structure of Pt, resulting in enhanced OH− adsorption and hydrogen oxidation reaction (HOR) activity. This multifaceted approach not only mitigates hydrogen accumulation but also boosts the overall BOR efficiency. The elaborate electrochemical measurements along with comprehensive characterizations elucidate the superior catalytic activity and stability of Pt–Ni/C over commercial Pt/C catalysts. Specifically, DBFCs employing the Pt–Ni/C catalyst manifest considerably higher open circuit voltage (1.05 V), peak power density (1.82 W cm−2) and fuel efficiency (63.96 %) than those of DBFCs employing Pt/C catalyst. Through these efforts, we provide significant insight into the design of high-performance anode catalyst for DBFCs.

Influence of Chromium Carbide-Derived Carbon Support and Ceria Nanocrystals on Pt–CeO2/C Catalysts for Fuel Cell Applications

The influence of different synthesis parameters on CeO2 and Pt nanoparticle (NP) deposition on Ketjenblack carbon (C(KB)) was examined. The Pt NP diameter (3.1–4.1 nm) was not influenced by CeO2 synthesis parameters. The CeO2 NPs synthesized using ultrasound sonication contribute to a better durability of the Pt–CeO2/C against CO poisoning. In contrast, CeO2 synthesized using the microwave heating method contributes to better methanol oxidation reaction (MOR) activity at low electrode potential. Synthesis parameters of CeO2 and Pt NPs developed for the C(KB)-based catalysts were applied for C(Cr3C2)-based catalysts. The Pt NP diameter of C(Cr3C2)-based catalysts was slightly higher (7.2 nm) as some Pt NPs were agglomerated. The C(Cr3C2) support facilitates the MOR and CO stripping, especially in the case of the Pt/C on C(Cr3C2) support. The MOR activity at 0.85 V of Pt NPs on the C(Cr3C2) support is as good as the MOR activity for the best Pt–CeO2 on the C(KB) support. The C(Cr3C2) support also improves the CO removal from the Pt surface. All the synthesized catalysts had better MOR activity than the commercial Pt/C(Vulcan) catalyst. The oxygen reduction reaction activity of Pt–CeO2/C catalysts with higher CeO2 content synthesized with the microwave heating method was very good.

Achieving a high-performance electrochemical sensor for electrochemical detection of ammonia–nitrogen based on electrodepositing PtAu alloys and polypyrrole on Ni foam

The environment pollution problmes resulting from ammonia-nitrogen have been paid more attentions. Efficient and accurate detection of ammonia–nitrogen in aqueous enivronment including tap water, lake water and sea water is meaningful. In this work, a novel PtAu alloy sensor was designed and fabricated via coelectrodeposition method on Ni foam (NF). In addition, polypyrrole (PPy) was electrochemically grown on NF surface to avoid corrosion of NF during the electrodepositing process of PtAu alloy. Under the optimal condition, the prepared Pt5Au3-PPy-NF-1 showed the great electrocatalytic performance for ammonia oxidation reaction with the current density of 15.55 mA and great detection ability with the high sensitivity of 8.2 µA µM−1, low detection limit of 1.05 µM and three linear ranges from 4 to 50 µM, from 50 to 400 µM and from 400 to 1000 µM. The enhanced performances could be attriubted to: 1) Pt showed the electrochemial catalytic activity for ammonia oxidation reaction and Au showed the lower adsortion energy to N atom, as well as optimized electronic structure of Pt and Au.

Mesoporous Pdx-Nix aerogels for electrocatalytic evaluation of urea-assisted electrolysis

This work presents the synthesis and evaluation of Pd-Ni aerogels toward the urea oxidation reaction (UOR). The incorporation of Ni led to a 0.13 V reduction in the energy required for the oxidation and reduction of PdO compared to monometallic Pd, both in alkaline medium with and without urea. Varying the Ni ratios in Pd (Pd-Ni 4:1, Pd-Ni 1:1, and Pd-Ni 1:4) led to significant changes in the electrochemical behaviour. In alkaline medium without urea, PdNi 4:1 showed the formation of NiOOH at 1.35 V, which promoted oxygen diffusion on the electrode surface and increased the current density, confirming the increase in the active sites of NiOOH and NiPdOOH and enabling urea-based electrolysis at these sites. While palladium aerogels alone are ineffective for UOR, the presence of nickel plays a key role in enhancing the UOR efficiency. On the other hand, physicochemical characterisation revealed that PdNi 4:1 has a crystal size of 4.37 nm and a larger shift in the 2θ positions of the (111) and (200) planes, which favours electronic changes that were investigated by XPS. These changes affected the electrocatalytic activity, which is primarily related to electronic effects. The results of SEM and TEM studies and nitrogen adsorption-desorption isotherm confirmed that the aerogels are highly porous and have an effective surface area and abundant active sites for reactions that allow efficient mass transfer and low diffusion resistance. TEM observations revealed interconnected nanochains indicating optimal electrocatalytic activity for both ORR and UOR due to high mass transfer. These interconnected networks are crucial for improving electrocatalytic activity in the urea oxidation reaction.

Breaking Highly Ordered PtPbBi Intermetallic with Disordered Amorphous Phase for Boosting Electrocatalytic Hydrogen Evolution and Alcohol Oxidation.

Constructing amorphous/intermetallic (A/IMC) heterophase structures by breaking the highly ordered IMC phase with disordered amorphous phase is an effective way to improve the electrocatalytic performance of noble metal-based IMC electrocatalysts because of the optimized electronic structure and abundant heterophase boundaries as active sites. In this study, we report the synthesis of ultrathin A/IMC PtPbBi nanosheets (NSs) for boosting hydrogen evolution reaction (HER) and alcohol oxidation reactions. The resulting A/IMC PtPbBi NSs exhibit a remarkably low overpotential of only 25 mV at 10 mA cm-2 for the HER in an acidic electrolyte, together with outstanding stability for 100 h. In addition, the PtPbBi NSs show high mass activities for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), which are 13.2 and 14.5 times higher than those of commercial Pt/C, respectively. Density functional theory calculations demonstrate that the synergistic effect of amorphous/intermetallic components and multimetallic composition facilitate the electron transfer from the catalyst to key intermediates, thus improving the catalytic activity of MOR. This work establishes a novel pathway for the synthesis of heterophase two-dimensional nanomaterials with high electrocatalytic performance across a wide range of electrochemical applications.

Breaking Highly Ordered PtPbBi Intermetallic with Disordered Amorphous Phase for Boosting Electrocatalytic Hydrogen Evolution and Alcohol Oxidation

AbstractConstructing amorphous/intermetallic (A/IMC) heterophase structures by breaking the highly ordered IMC phase with disordered amorphous phase is an effective way to improve the electrocatalytic performance of noble metal‐based IMC electrocatalysts because of the optimized electronic structure and abundant heterophase boundaries as active sites. In this study, we report the synthesis of ultrathin A/IMC PtPbBi nanosheets (NSs) for boosting hydrogen evolution reaction (HER) and alcohol oxidation reactions. The resulting A/IMC PtPbBi NSs exhibit a remarkably low overpotential of only 25 mV at 10 mA cm−2 for the HER in an acidic electrolyte, together with outstanding stability for 100 h. In addition, the PtPbBi NSs show high mass activities for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), which are 13.2 and 14.5 times higher than those of commercial Pt/C, respectively. Density functional theory calculations demonstrate that the synergistic effect of amorphous/intermetallic components and multimetallic composition facilitate the electron transfer from the catalyst to key intermediates, thus improving the catalytic activity of MOR. This work establishes a novel pathway for the synthesis of heterophase two‐dimensional nanomaterials with high electrocatalytic performance across a wide range of electrochemical applications.

Accumulated charge density at the interface boosts the urea oxidation reaction activity of Ni3N/Ni3S2 heterointerface

Optimizing the adsorption strength of multiple intermediates at one single active site at the same time is rather difficult. Heterointerface engineering provides more than one type of active sites to function, which may dramatically enhance the intrinsic urea oxidation reaction (UOR) activity of catalysts. Herein, a Ni3N (110)/Ni3S2 (010) heterointerface was fabricated. The electronic interactions between the two phases generates an accumulated charge density heterointerface and endows the heterointerface with more enhanced density of states, which facilitates the adsorption and desorption of more UOR intermediates, thus lowering the theoretical reaction barrier for the rate-controlling step of *CONHN to *CONN. The nickel moieties on Ni3N side tends to bond carbonyl and the nickel moieties on Ni3S2 side preferentially bond amnio. The cooperation of both nickel moieties contributes to the superb intrinsic UOR activity of Ni3N (110)/Ni3S2 (010) heterointerface. As a consequence, Ni3N (110)/Ni3S2 (010) heterointerface showcases outstanding UOR activity, reaching 105.66 mA·cm−2 at 1.6 V. This work provides an excellent UOR catalyst and helps to better understand the cooperation mechanism of the active sites at the heterointerface.

Production of H2 and Glucaric Acid Using Electrocatalyst Glucose Oxidation by the Ta NiFe LDH Electrode.

The slow anodic oxygen evolution reaction (OER) significantly limits electrocatalytic water splitting for hydrogen production. We proposed the electrocatalyst for glucose oxidation by Ta-doping NiFe LDH nanosheets to simultaneously obtain glucaric acid (GRA) and hydrogen gas as a useful byproduct. Superior glucose oxidation reaction (GOR) activity is demonstrated by the optimized Ta-NiFe LDH, which has a low overpotential of 192 mV, allowing for a small Tafel slope of 70 mV dec-1 and a current density of 50 mA cm-2. The Ta NiFe LDH-oxidized glucose to GRA with a 72.94% yield and 64.3% Faradaic efficiency at 1.45 VRHE. Herein, we report the Ta NiFe LDH/NF electrode for the GOR&hydrogen evolution reaction (HER), which exhibits a cell voltage of 1.62 V to reach a current density of 10 mA cm-2, which is 250 mV lower compared to OER&HER (1.87 V). This study reveals that GOR is an energy-efficient and cost-effective method for producing H2 and valorizing biomass.

Porous Ruthenium-Tungsten-Zinc Nanocages for Efficient Electrocatalytic Hydrogen Oxidation Reaction in Alkali.

With the rapid development of anion exchange membrane technology and the availability of high-performance non-noble metal cathode catalysts in alkaline media, the commercialization of anion exchange membrane fuel cells has become feasible. Currently, anode materials for alkaline anion-exchange membrane fuel cells still rely on platinum-based catalysts, posing a challenge to the development of efficient low-Pt or Pt-free catalysts. Low-cost ruthenium-based anodes are being considered as alternatives to platinum. However, they still suffer from stability issues and strong oxophilicity. Here, we employ a metal-organic framework compound as a template to construct three-dimensional porous ruthenium-tungsten-zinc nanocages via solvothermal and high-temperature pyrolysis methods. The experimental results demonstrate that this porous ruthenium-tungsten-zinc nanocage with an electrochemical surface area of 116 m2 g-1 exhibits excellent catalytic activity for hydrogen oxidation reaction in alkali, with a kinetic density 1.82 times and a mass activity 8.18 times higher than that of commercial Pt/C, and a good catalytic stability, showing no obvious degradation of the current density after continuous operation for 10,000 s. These findings suggest that the developed catalyst holds promise for use in alkaline anion-exchange membrane fuel cells.

What Elements Really Intercalate into Pd Lattice When Heated in Dimethylformamide?

Palladium hydrides (PdHx) are pivotal in both fundamental research and practical applications across a wide spectrum. PdHx nanocrystals, synthesized by heating in dimethylformamide (DMF), exhibit remarkable stability, granting them widespread applications in the field of electrocatalysis. However, this stability appears inconsistent with their metastable nature. The substantial challenges in characterizing nanoscale structures contribute to the limited understanding of this anomalous phenomenon. Here, through a series of well-conceived experimental designs and advanced characterization techniques, including aberration-corrected scanning transmission electron microscopy (AC-STEM), in situ X-ray diffraction (XRD), and time-of-flight secondary ion mass spectrometry (TOF-SIMS), we have uncovered evidence that indicates the presence of C and N within the lattice of Pd (PdCxNy), rather than H (PdHx). By combining theoretical calculations, we have thoroughly studied the potential configurations and thermodynamic stability of PdCxNy, demonstrating a 2.5:1 ratio of C to N infiltration into the Pd lattice. Furthermore, we successfully modulated the electronic structure of Pd nanocrystals through C and N doping, enhancing their catalytic activity in methanol oxidation reactions. This breakthrough provides a new perspective on the structure and composition of Pd-based nanocrystals infused with light elements, paving the way for the development of advanced catalytic materials in the future.

An all-metallic nanovesicle for hydrogen oxidation.

Vesicle, a microscopic unit that encloses a volume with an ultrathin wall, is ubiquitous in biomaterials. However, it remains a huge challenge to create its inorganic metal-based artificial counterparts. Here, inspired by the formation of biological vesicles, we proposed a novel biomimetic strategy of curling the ultrathin nanosheets into nanovesicles, which was driven by the interfacial strain. Trapped by the interfacial strain between the initially formed substrate Rh layer and subsequently formed RhRu overlayer, the nanosheet begins to deform in order to release a certain amount of strain. Density functional theory (DFT) calculations reveal that the Ru atoms make the curling of nanosheets more favorable in thermodynamics applications. Owing to the unique vesicular structure, the RhRu nanovesicles/C displays excellent hydrogen oxidation reaction (HOR) activity and stability, which has been proven by both experiments and DFT calculations. Specifically, the HOR mass activity of RhRu nanovesicles/C are 7.52 A mg(Rh+Ru)-1 at an overpotential of 50mV at the rotating disk electrode (RDE) level; this is 24.19 times that of commercial Pt/C (0.31mA mgPt-1). Moreover, the hydroxide exchange membrane fuel cell (HEMFC) with RhRu nanovesicles/C displays a peak power density of 1.62W cm-2 in the H2-O2 condition, much better than that of commercial Pt/C (1.18W cm-2). This work creates a new biomimetic strategy to synthesize inorganic nanomaterials, paving a pathway for designing catalytic reactors.

Pt nanorods supported on Nb-doped ceria: A promising anode catalyst for polymer electrolyte fuel cells

For polymer electrolyte fuel cells (PEFCs), platinum nanoparticles supported on carbon black (Pt/C) serve as the commonly used hydrogen anode catalyst, exhibiting high activity for the hydrogen oxidation reaction (HOR), while the carbon support is susceptible to corrosion under PEFC operation. Here, a highly active HOR anode catalyst of Pt nanorod supported on niobium (Nb)-doped ceria without using corrosive carbon support was developed, which exhibits high durability at high potentials associated with hydrogen starvation. The production of hydrogen peroxide (H2O2), which can degrade the polymer electrolyte membrane, was also found to be significantly suppressed on the Pt nanorod/doped ceria catalyst. Density functional theory (DFT) calculations suggests that the Pt nanorod geometry and interaction with Nb and Ce favor HOR activity and stability while suppressing H2O2 production by modulating the adsorption of key reaction intermediates. This new catalyst has the potential to be used as an anode for high-performance and high-durability PEFCs.

One-step constructing advanced N-doped carbon@metal nitride as ultra-stable electrocatalysts via urea plasma under room temperature

Highly active transition metal nitrides are desirable for electrocatalytic reactions, but their long-term stability is still unsatisfactory and thus limiting commercial applications. Herein, for the first time, we report a unique and universal room-temperature urea plasma method for controllable synthesis of N-doped carbon coated metal (Fe, Co, Ni, etc.) nitrides arrays electrocatalysts. The preformed metal oxides arrays can be successfully converted into metal nitrides arrays with preserved nanostructures and a thin layer of N-doped carbon (NC) via one-step urea plasma. Typically, as a representative case, NC@CoN nanowire arrays are illustrated and corresponding formation mechanism by plasma is proposed. Notably, the designed NC@CoN catalysts deliver excellent electrocatalytic activity and long-term stability both in oxygen evolution reaction (OER) and urea oxidation reaction (UOR). For OER, a low overpotential (264 mV at 10 mA/cm2) and high stability (>50 h at 20 mA/cm2) are acquired. For UOR, a current density of 100 mA/cm2 is achieved at only 1.39 V and maintain over 100 h. Theoretical calculations reveal that the synergetic coupling effect of CoN and NC can significantly facilitate the charge-transfer process, optimize adsorbed intermediates binding strength and further greatly decrease the energy barrier. This strategy provides a novel method for fabrication of NC@ metal nitrides as highly active and stable catalysts.

A High-Performance and Durable Direct-Ammonia Symmetrical Solid Oxide Fuel Cell with Nano La0.6Sr0.4Fe0.7Ni0.2Mo0.1O3-δ-Decorated Doped Ceria Electrode.

Solid oxide fuel cells (SOFCs) offer a significant advantage over other fuel cells in terms of flexibility in the choice of fuel. Ammonia stands out as an excellent fuel choice for SOFCs due to its easy transportation and storage, carbon-free nature and mature synthesis technology. For direct-ammonia SOFCs (DA-SOFCs), the development of anode catalysts that have efficient catalytic activity for both NH3 decomposition and H2 oxidation reactions is of great significance. Herein, we develop a Mo-doped La0.6Sr0.4Fe0.8Ni0.2O3-δ (La0.6Sr0.4Fe0.7Ni0.2Mo0.1O3-δ, LSFNM) material, and explore its potential as a symmetrical electrode for DA-SOFCs. After reduction, the main cubic perovskite phase of LSFNM remained unchanged, but some FeNi3 alloy nanoparticles and a small amount of SrLaFeO4 oxide phase were generated. Such reduced LSFNM exhibits excellent catalytic activity for ammonia decomposition due to the presence of FeNi3 alloy nanoparticles, ensuring that it can be used as an anode for DA-SOFCs. In addition, LSFNM shows high oxygen reduction reactivity, indicating that it can also be a cathode for DA-SOFCs. Consequently, a direct-ammonia symmetrical SOFC (DA-SSOFC) with the LSFNM-infiltrated doped ceria (LSFNM-SDCi) electrode delivers a superior peak power density (PPD) of 487 mW cm-2 at 800 °C when NH3 fuel is utilised. More importantly, because Mo doping greatly enhances the reduction stability of the material, the DA-SSOFC with the LSFN-MSDCi electrode exhibits strong operational stability without significant degradation for over 400 h at 700 °C.

High Entropy Alloys Enable Durable and Efficient Lithium-Mediated CO2 Redox Reactions.

Designing electrocatalysts with high activity and durability for multistep reduction and oxidation reactions is challenging. High-entropy alloys (HEAs) are intriguing due to their tunable geometric and electronic structure through entropy effects. However, understanding the origin of their exceptional performance and identifying active centers is hindered by the diverse microenvironment in HEAs. Herein, NiFeCoCuRu HEAs designed with an average diameter of 2.17 nm, featuring different adsorption capacities for various reactants and intermediates in Li-mediated CO2 redox reactions, are introduced. The electronegativity-dependent nature of NiFeCoCuRu HEAs induces significant charge redistribution, shifting the d-band center closer to Fermi level and forming highly active clusters of Ru, Co, and Ni for Li-based compounds adsorptions. This lowers energy barriers and simultaneously stabilizes *LiCO2 and LiCO3+CO intermediates, enhancing the efficiency of both CO2 reduction and Li2CO3 decomposition over extended periods. This work provides insights into specific active site interactions with intermediates, highlighting the potential of HEAs as promising catalysts for intricate CO2 redox reactions.

Tailoring competitive adsorption sites of hydroxide ion to enhance urea oxidation-assisted hydrogen production

Alloys with bimetallic electron modulation effect are promising catalysts for the electrooxidation of urea. However, the side reaction oxygen evolution reaction (OER) originating from the competitive adsorption of OH− and urea severely limited the urea oxidation reaction (UOR) activity on the alloy catalysts. This work successfully constructs the defect-rich NiCo alloy with lattice strain (PMo-NiCo/NF) by rapid pyrolysis and co-doping. By taking advantage of the compressive strain, the d-band center of NiCo is shifted downward, inhibiting OH− from adsorbing on the NiCo site and avoiding the detrimental OER. Meanwhile, the oxygenophilic P/Mo tailored specific adsorption sites to adsorb OH− preferentially, which further released the NiCo sites to ensure the enriched adsorption of urea, thus improving the UOR efficiency. As a result, PMo-NiCo/NF only requires 1.27 V and −57 mV to drive a current density of ±10 mA cm−2 for UOR and hydrogen evolution reaction (HER), respectively. With the guidance of this work, reactant competing adsorption sites could be tailored for effective electrocatalytic performance.