Bifunctional Catalytic Activity Research Articles

Precisely Constructing Orbital-Coupled Fe─Co Dual-atom Sites for High-Energy-Efficiency Zn-Air/Iodide Hybrid Batteries.

Rechargeable Zn-air batteries (ZABs) are promising for energy storage and conversion. However, the high charging voltage and low energy efficiency hinder their commercialization. Herein, these challenges are addressed by employing precisely constructed multifunctional Fe-Co diatomic site catalysts (FeCo-DACs) and integrating iodide/iodate redox into ZABs to create Zinc-air/iodide hybrid batteries (ZAIHBs) with highly efficient multifunctional catalyst. The strong coupling between the 3d orbitals of Fe and Co weakens the excessively strong binding strength between active sites and intermediates, enhancing the catalytic activities for oxygen reduction/evolution reaction and iodide/iodate redox. Consequently, FeCo-DACs exhibit outstanding bifunctional oxygen catalytic activity with a small potential gap (ΔE=0.66V) and outstanding stability. Moreover, an outstanding catalytic performance toward iodide/iodate redox is obtained. Therefore, FeCo-DAC-based ZAIHBs exhibit high energy efficiency of up to 75% at 10mAcm-2 and excellent cycling stability (72% after 500h). This research offers critical insights into the rational design of DACs and paves the way for high-energy efficiency energy storage devices.

MoO3/V2O5/Ni(OH)2 with multiple heterojunction interfaces for the hydrogen preparation from urea-containing wastewater

Compared to a single heterostructure, constructing multiple heterojunction interfaces to enhance bifunctional catalytic activity still faces challenges. Herein, a nanoflower-like electrocatalyst with multiple heterojunction interfaces, which consists of MoO3, V2O5, and Ni(OH)2 in-situ grown on nickel foam, is prepared through a one-step hydrothermal method (MoO3/V2O5/Ni(OH)2/NF, named MVN/NF). The MVN/NF exhibits superior catalytic performance, attributable to enhanced electron transfer facilitated by numerous heterojunction interfaces, a substantial active specific surface area, and a self-supported architecture. It requires low potentials for hydrogen evolution reaction, urea oxidation reaction, and overall urea electrolysis of 81 mV, 1.351 V, and 1.450 V (vs. RHE), respectively, to reach a current density of 10 mA cm-2. By cutting the material into a large-scale electrode for use in an alkaline electrolyzer, its Faraday efficiency was 90.0%, and the urea decomposition rate reached 45.1%. This work offers broad application prospects for the realization of large-scale hydrogen production and the decomposition of urea-containing wastewater.

Recycling the spent cobalt-based perovskites for the high-active oxygen catalysts in zinc-air batteries

Cobalt (Co) is widely used in energy storage and conversion devices, although its content on our planet is not adequate. Therefore, recycling Co from the spent Co-enriched materials is indispensable. Co-based perovskites, which contain abundant Co, are extensively utilized in solid oxide fuel cells, three-way catalysts, and oxygen-permeable membranes, and the recovery of Co from the spent Co-based perovskites is necessary to meet the long-term requirement of Co. In this work, a facile and universal thermal reduction method (750 °C and N2 atmosphere) is employed to convert the spent cobalt-based perovskites into high-performance bifunctional oxygen catalysts for zinc-air batteries (ZABs), achieving high-efficient Co recovery and re-utilization. At high temperatures, melamine and dopamine hydrochloride are transformed into carbon nanotubes, C3N4 and reducing gases (such as NH3 and H2). Simultaneously, the metal elements in the spent Co-based perovskites (SrNb0.1Co0.7Fe0.2O3,SNCF) are converted into nano-scale alloy particles and metal nitrides. Then, the phase structures, micromorphology, and element valences of the obtained multiphase oxygen catalyst (SNCF–Ni-PM) are characterized by X-ray diffraction, scanning/transmission electron microscopy, and X-ray photoelectron spectroscopy, respectively. The electrochemical properties, including oxygen catalytic activities and stability, of SNCF-Ni-PM are measured by linear sweep voltammetry, chronopotentiometry, chronoamperometry, and cyclic voltammetry methods. Considering the practical applications, the aqueous and solid-state ZABs are assembled and measured. The results demonstrate that the multiphase SNCF-Ni-PM mainly includes carbon nanotubes, C3N4 nanosheets, and FeNiN or CoFe nanoparticles. Moreover, SNCF-Ni-PM exhibits excellent bifunctional oxygen catalytic activity, with an oxygen evolution reaction (OER) potential at 10 mA cm−2 of 1.51 V and an oxygen reduction reaction (ORR) half-wave potential of 0.77 V, outperforming most of the reported oxygen catalysts. Using SNCF-Ni-PM, the aqueous and solid-state ZABs can achieve high power densities of 295.9 and 228.4 mW cm−2, respectively, being superior to most ZABs. In addition, the aqueous ZAB with SNCF-Ni-PM can operate stably for 300 h with a slight degradation. This work provides a feasible method for effectively recycling Co from the spent Co-based perovskites.

In Situ Construction of Biphasic Boride Electrocatalysts on Dealloyed Bulk Ni-Mo Alloy as Self-Supporting Electrode for Water Splitting at High Current Density.

Nickel-molybdenum-boron (Ni-Mo-B)-based catalysts with biphasic interfaces are highly advantageous in bifunctional electrocatalytic activity in alkaline water-splitting. However, it remains an ongoing challenge to obtain porous Ni-Mo alloy substrates that provide stable adhesion to catalysts, ensuring the long-term performance of bifunctional self-supporting electrodes at a high current density. Herein, a porous Ni-Mo alloy substrate was effectively obtained by a cost-effective dealloying process on a commercial Ni-Mo alloy with high-energy crystal planes. Subsequently, the Mo2NiB2/Ni3B bifunctional catalyst was in situ synthesized on this substrate via boriding heat treatment, resulting in outstanding catalytic activity and stability. Density functional theory (DFT) calculations reveal that the abundant biphasic interfaces and surface-reconstructed sites of the Mo2NiB2/Ni3B catalyst can decrease the energy barriers for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Thus, the designed self-supporting electrodes show bifunctional catalytic activity with overpotentials of 151 mV for HER and 260 mV for OER at a current density of 10 mA cm-2. Markedly, the assembled water electrolyzer can be driven up to 10 mA cm-2 at 1.64 V and maintain catalytic activity at a high current density of 1000 mA cm-2 for 100 h. The new strategy is expected to provide a low-cost scheme for designing self-supporting bifunctional electrodes with high activity and excellent stability and contribute to the development of hydrogen energy technology.

Coupling of modulating d-band center and optimizing interface electronic structure via MXene and Bi-metal doping in CoP achieving efficient bifunctional catalytic activity for water splitting

Bifunctional electrocatalysts that exhibit excellent catalytic activity for both hydrogen (HER) and oxygen evolution reactions (OER) are ideal for alkaline overall water splitting. The unique structure and diverse composition of cobalt phosphide catalysts are highly favorable for enhancing catalytic reaction kinetics. However, cobalt phosphide electrocatalysts typically exhibit insufficient OER activity. To overcome this text, we synthesized a Ru and V co-doped CoP-coupled highly conductive MXene catalyst with nano-arrays by in-situ growth on the surface of carbon cloth. The HER and OER overpotentials of the catalyst at 10 mA cm−2 current density were 30 and 206 mV, respectively. Furthermore, a series of physicochemical characterizations and first-principles calculations demonstrated that the increased HER and OER activities resulted from the synergistic effect established by the double doping and heterostructure. This effect produced an effective modulation of the d-band center of the catalysts, promoting adsorption effects on the intermediates. In conclusion, this work presents a novel approach to improving the electrocatalytic activity of phosphides and provides a faster and more environmentally friendly method for separating hydrogen from water.

Performance of Nitrogen-Doped Carbon Nanoparticles Carrying FeNiCu as Bifunctional Electrocatalyst for Rechargeable Zinc-Air Battery.

Catalysts for zinc-air batteries (ZABs) must be stable over long-term charging-discharging cycles and exhibit bifunctional catalytic activity. In this study, by doping nitrogen-doped carbon (NC) materials with three metal atoms (Fe, Ni, and Cu), a single-atom-distributed FeNiCu-NC bifunctional catalyst is prepared. The catalyst includes Fe(Ni-doped)-N4 for the oxygen evolution reaction (OER), Fe(Cu-doped)-N4 for the oxygen reduction reaction (ORR), and the NiCu-NC catalytic structure for the oxygen reduction reaction (ORR) in the nitrogen-doped carbon nanoparticles. This single-atom distribution catalyst structure enhances the bifunctional catalytic activity. If a trimetallic single-atom catalyst is designed, it will surpass the typical bimetallic single-atom catcalyst. FeNiCu-NC exhibits outstanding performance as an electrocatalyst, with a half-wave potential (E1/2) of 0.876V versus RHE, overpotential (Ej = 10) of 253mV versus RHE at 10mA cm-2, and a small potential gap (ΔE = 0.61V). As the anode in a ZAB, FeNiCu-NC can undergo continuous charge-discharged cycles for 575h without significant attenuation. This study presents a new method for achieving high-performance, low-cost ZABs via trimetallic single-atom doping.

Systematic exploration of N, O coordination number on the catalytic performance for oxygen reduction and oxygen evolution

The reaction rate of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is an important factor restricting its application. In this work, we have systematic explorated of N, O coordination number on the catalytic performance for ORR and OER. Firstly, a variety of stability analysis methods show that most of the catalysts have excellent stability. Secondly, a series of excellent bifunctional catalysts are screened by volcanic maps, ORR overpotential (ηORR), OER overpotential (ηOER), and bifunctional index (BI), such as, RhN3O1-1 (ηORR = 0.28 V, ηOER = 0.34 V, BI = 0.62 V) and CoN3O1-1 (ηORR = 0.33 V, ηOER = 0.37 V, BI = 0.70 V). In particular, RhN3O1-1 has the smallest BI value, indicating that it has the best bifunctional catalytic activity. This study offers insights into how the coordination environment affects the activity of OER/ORR.

Copper-bonded polyoxomolybdates-based framework as a heterogeneous catalyst for the cascade click reaction and bromination

The selective conversion of alkynes into bromotriazoles over a single-component catalyst is highly desirable but presents significant challenges. In this study, we developed a robust copper-bonded polyoxomolybdates-based framework [Cu2(Mo6O20)]·2H2O (CPF-1), and it integrates the catalytic ability of Cu(I) site with the multielectron-transfer ability of polyoxometalates. As a result, CPF-1 exhibits favorable bifunctional catalytic activity for click chemistry and achieves 99% yield in the conversion of corresponding products to bromotriazoles. To our knowledge, CPF-1 represents the first heterogeneous catalyst that significantly enhances cascade reaction with excellent efficiency and sustainable recyclability. Additionally, the possible cascade catalytic mechanisms of these two reactions are also proposed.

Multifunctional carbon armor: Synchronously improving oxygen reaction kinetics, mass transfer dynamics, and robustness of transition metal alloy based hybrid catalyst

Construction of robust protective cover on delicate active sites is a frequently-used scheme to enhance the durability of air-cathode catalyst working in harsh environment, thus the lifespan of rechargeable Zinc-air batteries (ZABs). Paradoxically, this would degrade the activity due to the constricted accessibility of active sites to reactants. Herein, carbon nanotubes with abundant mesoporous defects and Fe-N4 species were elaborately designed to be multifunctional protective armor to encapsulate Ni3Fe nano-alloys (Ni3Fe@CNTs/Fe-N4) for bifunctional oxygen electrocatalyst. In/ex-situ spectroscopy analysis and theoretical calculations reveal that the constructed mesoporous carbon defects effectively facilitate the multiphase mass transfer and the oxygen evolution reaction kinetics via strong electrons coupling with packaged Ni3Fe nano-alloys. Meanwhile, the synchronously introduced Fe-N4 moieties could serve as oxygen reduction active sites. Thus, the obtained Ni3Fe@CNTs/Fe-N4 hybrid electrocatalyst simultaneously exhibits remarkable bifunctional catalytic activity (E1/2=0.86/Ej=10=1.59 V vs RHE) and durability over 450 h in the chronoamperometric test at 1.59 V, endowing the assembled Zn-air batteries (ZABs) with a high power density (150 mW cm−2) and lifespan (307 h), much better than that employing benchmark Pt/C+RuO2 mixed catalyst. This work demonstrates an innovative design route for the multifunctional armor to concurrently enhance the durability, activity and robustness of air-cathode-catalyst for ZABs.

Investigating the electrochemical performance of Mn3O4/MoMn2P12 mixed-phase catalyst on MWCNT for high specific energy supercapacitors and HER/OER reactions

A versatile Mn/MoMn hybrid oxide/phosphide composite (MnO/MoMnP) supported on MWCNT is synthesized using hydrothermal method and in-situ phosphorization methods. This composite serves as a catalyst for supercapacitors and oxygen and hydrogen evolution reactions (OER/HER) in electrochemical water splitting. XRD analysis confirmed the presence of mixed-phase of Mn3O4 and MoMn2P12. Electrochemical tests revealed exceptional charge storage performance for MnO/MoMnP/MWCNT, with a high specific capacitance(436 F g−1 at 1 A g−1) and impressive capacitance retention (96.51 % for 5000 cycles at 15 A g−1). This performance surpasses that of bare MnO/MoMnP by 50 %. Furthermore, we assembled a MnO/MoMnP/MWCNT//MWCNT device, that achieved a remarkable energy density of 128.11 W h kg−1 at an ultra-high-power density of 1920 W kg−1, along with excellent cycling stability (92.5 % for 5000 cycles). Moreover, the MnO/MoMnP/MWCNT composite exhibited a remarkable bifunctional electro catalytic activity for OER and HER, with low overpotentials of 335 and 430 mV at 10 mA cm−2 in 1 M KOH solution. These results highlight MnO/MoMnP/MWCNT as a promising and efficient alternative catalyst for future applications in supercapacitors and water electrolysis.

Ultrafine Ru nanoparticles anchored on N-doped mesoporous hollow carbon spheres as a highly efficient bifunctional catalyst for Li–CO2 batteries

Rechargeable Li–CO2 battery is a facilitative and promising device for the conversion of CO2 to electrochemical energy. However, it remains a challenge to enhance the sluggish decomposition kinetics of lithium carbonate as the discharge product. Herein, the Ru nanoparticles anchored on N-doped mesoporous hollow carbon nanospheres (Ru-AHCNs) are designed as cathode to enhance the electrochemical performance of Li–CO2 battery. The Ru-AHCNs cathode displays a high discharge specific capacity of 11194.4 mA h g−1 at the current density of 100 mA g−1. In addition, the Ru-AHCNs cathode can stably run over 50 cycles and maintain a small overpotential (<1.38 V) with a limited capacity of 1000 mA h g−1 at 100 mA g−1. The excellent stability and catalytic activity of the cathode are ascribed to the following factors: (i) Uniform deposition of Ru nanoparticles in hollow carbon nanospheres can enhance the decomposition of Li2CO3 and provide considerable exposure to active sites. (ii) N-doped mesoporous hollow carbon nanospheres can provide abundant electron transport channels and promote the nucleation of discharge products. These results evidently prove the reversible formation and decomposition of the discharge products, indicating that Ru-AHCNs cathode possesses excellent bifunctional catalytic activity.

FeNi alloy embedded in three-dimensional nitrogen-doped porous carbon as bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries

Iron‑nickel (FeNi) alloy is one of the efficient bifunctional oxygen electrocatalysts for zinc-air batteries (ZABs). However, FeNi alloy nanoparticles prepared by traditional synthesis strategies are easy to agglomerate and have non-uniform sizes, which is not conducive to the improvement of catalytic activity and stability. Here, we have successfully encapsulated two different kinds of nitrogen-rich metal phthalocyanines (MPcs) in situ doping in zeolitic imidazolate framework (ZIF-8) homogeneously by the “double solvents” method. The ligand nitrogen and macrocyclic structure of MPcs encapsulated in ZIF-8 not only helps metal dispersion and enhances the metal-ligand‑nitrogen (M-Nx) structure, but also enhances the graphitisation of three-dimensional (3D) porous carbon after pyrolysis. Thus, a FeNi alloy uniformly embedded in 3D nitrogen-doped porous carbon materials (FeNi@NC) was constructed in the subsequent pyrolysis process and used as an efficient bifunctional oxygen reduction/evolution (ORR/OER) electrocatalyst for rechargeable ZABs. Impressively, the FeNi@NC catalyst carries high half-wave potential (0.850 V) in ORR and the low overpotential (291 mV) in OER, significantly better than Pt/C (0.830 V) and RuO2 (307 mV), respectively. In addition, the rechargeable ZAB assembled with FeNi@NC air cathode has a specific capacity of 649 mW cm−2 and shows no significant degradation after 240 h of charging and discharging cycles. This study provides a new design idea for the manufacture of carbon-supported non-noble metal alloy catalysts with bifunctional oxygen catalytic activity, and verifies the feasibility of regulating the composition of non-noble metals to construct a rechargeable ZABs with excellent performance.

Bimetal organic framework derived CoM@N–C composites as bifunctional oxygen catalysts for Zn-air batteries

Metal-loaded nitrogen-doped carbon (M@N–C) catalysts have shown promise as electrocatalysts for replacing noble metal catalysts in industrial processes. To study the influence on structural and performance caused by different bimetal doping, a family of bimetals CoM@N–C (M = Cu/Ni/Fe) composites with porous surface and abundant C defects were well-designed. After bimetallic doping, more defects are introduced into the carbon frameworks, and the metal-N species are fixed. As such, efficient utilization of active sites and rapid mass transfer make the reaction kinetics process more favorable and stable. Density functional theory calculations indicate that Cu/Ni doping optimizes the electronic environment of the Co–N, resulting in the balanced adsorption and dissociation of oxygen intermediates. While the synergy of FeCo activates the O=O, which promotes the sharp decrease in free energy of ∗OOH to ∗O, shifting the rate-determining step for oxygen reduction reaction. This indicates the adsorption site transfer of CoFe0.05@N–C in oxygen reduction and evolution reactions. The CoFe0.05@N–C catalyst exhibits superior bifunctional catalytic activity (with a potential gap of 0.80 V) than that of Pt catalysts. This work presents a simple strategy to fabricate well-defined bimetals doping in bifunctional oxygen electrocatalysts and it is expected to inspire future work on the role of electronic structure modulation and interface engineering.

Designing core-shell heterostructure arrays based on snowflake NiCoFe-LTH shelled over W2N-WC nanowires as an advanced bi-functional electrocatalyst for boosting alkaline water/seawater electrolysis

The pursuit of efficient and sustainable hydrogen production through water splitting has led to intensive research in the field of electrocatalysis. However, the impediment posed by sluggish reaction kinetics has served as a significant barrier. This challenge has inspired the development of electrocatalysts characterized by high activity, abundance in earth's resources, and long-term stability. In addressing this obstacle, it is imperative to meticulously fine-tune the structure, morphology, and electronic state of electrocatalysts. By systematically manipulating these key parameters, the full potential of electrocatalysts can unleash, enhancing their catalytic activity and overall performance. Hence in this study, a novel heterostructure is designed, showcasing core–shell architectures achieved by covering W2N-WC nanowire arrays with tri-metallic Nickel-Cobalt-Iron layered triple hydroxide nanosheets on carbon felt support (NiCoFe-LTH/W2N-WC/CF). By integrating the different virtue such as binder free electrode design, synergistic effect between different components, core–shell structural advantages, high exposed active sites, high electrical conductivity and heterostructure design, NiCoFe-LTH/W2N-WC/CF demonstrates striking catalytic performances under alkaline conditions. The substantiation of all the mentioned advantages has been validated through electrochemical data in this study. According to these results NiCoFe-LTH/W2N-WC/CF achieves a current density of 10 mA cm−2 needs overpotential values of 101 mV for HER and 206 mV for OER, respectively. Moreover, as a bi-functional electrocatalyst for overall water splitting, a two-electrode device needs a voltage of 1.543 V and 1.569 V to reach a current density of 10 mA cm−2 for alkaline water and alkaline seawater electrolysis, respectively. Briefly, this research with attempting to combination of different factors try to present a promising stride towards advancing bi-functional catalytic activity with tailored architectures for practical green hydrogen production via electrochemical water splitting process.

Self-Powered Water Splitting of Ni3FeN@Fe24N10 Bifunctional Catalyst Improved Catalytic Activity and Durability by Forming Fe24N10 on Catalyst Surface via the Kirkendall Effect.

Highly efficient water splitting electrocatalyst for producing hydrogen as a renewable energy source offers potential to achieve net-zero. However, it has significant challenges in using transition metal electrocatalysts as alternatives to noble metals due to their low efficiency and durability, furthermore, the reliance on electricity generation for electrocatalysts from fossil fuels leads to unavoidable carbon emissions. Here, a highly efficient self-powered water splitting system integrated is designed with triboelectric nanogenerator (TENG) and Ni3FeN@Fe24N10 catalyst with improved catalytic activity and durability. First, the durability of the Ni3FeN catalyst is improved by forming N, P carbon shell using melamine, polyetherimide, and phytic acid. The catalyst activity is improved by generating Fe24N10 in the carbon shell through the Kirkendall effect. The synthesized Ni3FeN@Fe24N10 catalyst exhibited excellent bifunctional catalytic activity (ηOER = 261.8 mV and ηHER = 151.8 mV) and remarkable stability (91.7% in OER and 90.5% in HER) in 1 m KOH. Furthermore, to achieve ecofriendly electricity generation, a rotation-mode TENG that sustainably generate high-performance is realized using butylated melamine formaldehyde. As a result, H2 is successfully generated using the integrated system composed of the designed TENG and catalyst. The finding provides a promising approach for energy generation to achieve net-zero.

Theoretical regulating the M-site composition of Janus MXenes enables the tailoring design for highly active bifunctional ORR/OER catalysts

Rechargeable metal-air batteries generally require efficient, durable, and safe bifunctional electrocatalysts to simultaneously support oxygen reduction/evolution reactions (ORR/OER). Herein, we employed first-principles calculations to explore the structure-activity relationship between the composition control of metal atoms and the catalytic activity of Pt-doped Ti2–xMnxCO2 single-atom catalysts (SACs). The research found a clear linear relationship between the proportion of Mn and bifunctional performance, which can effectively modulate catalytic activity. Additionally, it shows excellent bifunctional catalytic activity at medium concentrations, among which the catalyst of Pt-VO-Ti0.89Mn1.11CO2 displays the lowest overpotential (ηORR/OER = 0.26/0.28 V). Attributed to the modulation of the average magnetism of Mn and the d-band center of Pt by different components, the bonding strength of the active center of Pt to adsorption intermediates is changed, resulting in the enhancement of the catalyst activity. Crucially, the molecular orbital-level bonding between the active site Pt and the adsorbed intermediate OH is clarified, shedding light on the involvement of the partially occupied antibonding state of Pt's d orbital in the activation process. The research extensively explores the control of catalyst activity through composition, offering strong support for designing and optimizing highly active Janus MXene-supported SACs.

Construction of Co3S4/MoS2 p-p heterojunction as an efficient catalyst for water splitting and electrochemical oxidation of organic molecules

Electrolysis of wastewater containing urea or small organic molecules while obtaining hydrogen energy is a promising strategy for realizing energy acquisition and environmental protection. Construction of semiconductor heterojunctions to regulate the transfer of interfacial electrons has been regarded as an efficient approach to improve the electrocatalytic performance of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) for the materials, and obtain the bifunctional electrocatalysts aiming to construct a water splitting cell using one non-precious metal material. Herein, a bifunctional Co3S4/MoS2 electrocatalyst with a p-p heterojunction and hollow structure has been successfully prepared through the precipitation-hydrothermal method, which presents the high bifunctional electrocatalytic performance due to the formed path of electron transfer in the heterojunction interface being favorable for OH- adsorption. The accelerated electron transfer in heterojunction interfaces endows Co3S4/MoS2 presenting the superior electrocatalytic performance including OER, urea oxidation reaction (UOR) and oxygen evolution reaction in lactic acid solution (OER-LA). At 50 mA cm−2, the voltages of HER, OER, UOR and OER-LA are −0.123, 1.511, 1.400, 1.440 V vs. RHE, respectively. In a two-electrode electrolytic cell using Co3S4/MoS2 as anode and cathode displays the outstanding electrocatalytic performance in 1 M KOH, 1 M KOH containing 0.5 M urea, and 1 M KOH containing 0.5 M lactic acid electrolytes, superior to the most reported materials. This research provides a strategy for the construction of advanced bifunctional electrocatalysts using metal sulfides to form heterojunction for realizing the high bifunctional catalytic activities in hydrogen production and organic molecule decontamination.

Synthesis of nickel phosphate nanowires as a bifunctional catalyst for water electrolysis in alkaline media

The electrocatalytic water splitting (WS) process for hydrogen (H2) and oxygen (O2) production is known for its high efficiency, necessitating the development of bifunctional electrode materials. These materials must possess strong catalytic activity, significant active sites, high stability, and an abundance of earth-friendly components to ensure efficient and prolonged H2 and O2 generation. In this study, we employed a hydrothermal method to synthesize unique one-dimensional (1D) nickel phosphate (NiPO) nanoneedles directly grown on nickel foam (NF). The in-situ synthesis of the NiPO/NF catalyst offers favorable streamlining, facilitating electrode production and improving the contact between active sites and the conductive substrate. Under alkaline conditions, the NiPO/NF electrodes demonstrated low overpotentials of 374 mV and 377 mV at a high current density (J) of 250 mAcm−2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. These values indicate efficient and stable electrocatalytic activity. Moreover, the NiPO/NF catalyst exhibited continuous bifunctional catalytic activity for 12 hours with a J exceeding 20 mAcm−2. These findings suggest that NiPO/NF has the potential to be a cost-effective and sustainable option for large-scale WS applications.

Synergistic Effect of Trimetallic PdCuIn Nanoparticles in Ethanol and Formate Oxidation Reaction for Remarkable Catalytic Performance

Direct liquid fuel cells (DLFC) are regarded as attractive energy devices with their advantages of sustainability and eco‐friendly operation. Pd‐based materials have been recognized as ideal catalysts for anodic oxidation of DLFC. Although reasonably regulating the structure of Pd‐based catalysts to achieve remarkable catalytic performance, it is not clear about the combined effects of d‐band center and charge transfer, which are the crucial impactors for catalytic activity. Herein, a facile method to synthesize trimetallic PdCuIn nanoparticles (PdCuIn NPs) for ethanol and formate oxidation reactions (EOR and FOR, respectively) is reported. PdCuIn NPs exhibits bifunctional catalytic activities for both EOR and FOR, with mass activities of 16 000 and 15 500 mA mgPd−1, respectively, which are much better than those of commercial Pd/C catalysts. Comparing to the bimetallic nanoparticles (PdCu or PdIn NPs), additional Cu or In enhances the electron transfer and achieves a suitable d‐band center, resulting in excellent performance. This work synthesizes a highly active catalyst for both EOR and FOR, but also provides facile strategy of balancing the d‐band center and charge transfer for high catalytic performance.

Ni-Co ternary nitrides with multiple surface oxides as bifunctional oxygen electrocatalysts for metal-air batteries

The bifunctional non-noble metal catalysts based on the metal nitrides with high activity and high efficiency is very challenging for the development of high-performance metal-air batteries. Herein, a new Ni-Co ternary nitrides anchored on nitrogen-doped carbontubes (denoted as NiCoxN/CNT) is rationally designed by the thermal of corresponding hydroxide/carbontubes at low temperature, following nitridation. The synergistic effect between Ni-Co ternary nitrides (Ni4N, Co5.47N, CoN) effectively regulates the electronic configuration of the active site, thereby optimizing the chemisorption energy of the reaction intermediates, resulting in improved intrinsic catalytic activity. The result shows that NiCoxN/CNT not only exhibits excellent half-wave potential of 0.80 V for ORR but also with a low overpotential of 280 mV for OER at 10 mA cm−2, outperforming those of cobalt mononitride and nickel mononitride. Furthermore, Zn-air batteries assembled with NiCoxN/CNT show a high specific capacity of 826.9 mA h g−1 and excellent cycling stabilities up to 190 h in an aqueous electrolyte. More attractively, when assembled into Mg-air batteries, NiCoxN/CNT cathode realizes high power density of 112.38 mWcm−2. Therefore, the design and construction of multiple TMNs is a new guide to break through the bifunctional catalytic activity.