Low Tafel Slope Research Articles

Construction of porous flower-like Ru-doped CoNiFe layered double hydroxide for supercapacitors and oxygen evolution reaction catalysts

In recent years, ternary layered double hydroxide (LDH) has become a research hotspot for electrode materials and oxygen evolution reaction (OER) catalyst due to the enhanced synergistic effect between individual elements. However, the application of LDH is greatly limited by its low electrical conductivity and the disadvantage that nanosheets tend to accumulate and mask the active sites. Herein, a novel Ru-doped CoNiFe − LDH was prepared via a facile hydrothermal method. According to the density functional theory (DFT) calculations, the doping of Ru element could improve electron state density and band gaps of LDH and consequently boosted the electrochemical reaction kinetics as well as electrical conductivity. Furthermore, introduction of Ru atom induced the formation of porous flower-like structures in nanosheets. Compared to CoNiFe − LDH (28.9 m2/g), Ru-doped CoNiFe − LDH performed larger specific surface area of 53.1 m2/g, resulting in more electrochemically active sites. In these case, Ru-doped CoNiFe − LDH demonstrated better energy storage performance of 176.0 mAh/g at 1 A/g compared to original CoNiFe − LDH (78.9 mAh/g at 1 A/g). Besides, the assembled Ru-doped CoNiFe − LDH//activated carbon (AC) device delivered a maximum energy density of 36.4 W h kg−1 at the power density of 740.3 W kg−1 and an outstanding cycle life (78.7 % after 10,000 cycles). Meanwhile, Ru-doped CoNiFe − LDH exhibited lower overpotential (339 mV at 50 mA cm−2) and Tafel slope (93.2 mV dec−1). Therefore, this work provided novel and valuable insights into the rational doping of Ru elements for the controlled synthesis of supercapacitor electrode materials and OER catalysts.

Efficient removal of ammonia nitrogen via a coupled system of Ni1Cu0.2-Se-T/CP anode and copper foam cathode

Direct electrochemical oxidation is a green, clean and promising process for the treatment of ammonia nitrogen (NH4+-N) wastewater. Nevertheless, drawbacks of slow reaction kinetics and large overpotential greatly limit the ammonia oxidation reaction. To address the issue, Ni1Cu0.2-Se-T/CP was synthesized by the combination of heteroatom doping and in situ electrochemical oxidation (ISEO). Physical characterization shows that there are homogeneous and dense microscopic nanosphere particles on the electrode surface, which provide good attachment sites for the adsorption of reactants. Electrochemical tests further show that this catalytic electrode exhibits not only a high current density (37.17 mA·cm−2) at 0.65 V vs.Hg/HgO but also has the low Tafel slope (92.25 mV·dec−1) to ammonia oxidation reaction. Then, Ni1Cu0.2-Se-T/CP was applied as anode with copper as cathode to construct a coupled system. The area ratio of cathode/anode was optimized to improve the removal effect of ammonia nitrogen. The NH4+-N conversion efficiency of 100% was obtained at a constant anode potential of 0.65 V vs.Hg/HgO for 15 h when the cathode/anode area was 1:4. The system N2 selectivity up to 77.55%. This work provides a promising process for the green and efficient degradation of ammonia nitrogen wastewater.

Synthesis, structure and electrochemical properties of Co-MOF containing pyridine polycarboxylic acid

Metal-organic frameworks (MOFs) have been widely used in filed of electrochemistry. Compared with traditional inorganic porous materials, the polyvalent pyridinecarboxylic acid ligands have many advantages which contains more active sites, flexible coordination mode, adjustable structure. Therefore, it becomes good choice for constructing MOFs materials with excellent performance. In this paper, a novel MOF was synthesized by pyridine polycarboxylic acid ligand and CoCl2·6H2O using solvothermal method. The physicochemical properties were characterized by FT-IR, powder diffraction and thermogravimetry. Single crystal X-ray diffraction reveal that MOF-1 crystallizes in monoclinic system with P21/C space group. The central Co2+ ions have a dual core structure with 5 and 6 coordination, respectively. The carboxyl groups show two kinds of coordination modes μ2: η1: η1 and μ2: η1: η2, and the pyridine N atoms also coordinate to form a three-dimensional network structure. Electrochemical experiments show that MOF-1 has a lower overpotential (339.4 mV) and Tafel slope (65.3 mV·dec−1) with higher ECSA and better OER kinetics. A large number of exposed active sites indicate that the MOF has higher potential as catalyst for oxygen evolution reaction.

Promotion of oxygen evolution through the modification of Co-O bond in spinel NiCo2O4

The coordination environment of magnetic ions in transition metal oxides has a significant impact on the oxygen evolution reaction (OER) activity. Herein, we synthesized inverse spinel oxide NiCo2-xFexO4 (x = 0–1.5) on the nickel foam (NiCo2-xFexO4@NF) to explore the impact of Fe3+ ions doping in Co site on OER activity. The electrochemical results indicate that the introduction of Fe3+ ions drastically improved the OER performance for x ≤ 1.0. While the OER activity would decrease with further doping of Fe3+. The overpotential of 10 mA cm−2 decreased from 331 mV (NiCo2O4@NF) to 260 mV versus RHE (NiCoFeO4@NF) and lower Tafel slope (41.46 mV/dec) for OER in 1.0 M KOH electrolyte. Furthermore, there is a slightly decrease in overpotential after the stability test and the difference is not more than 2%. By comparing the structure of NiCoFeO4@NF and pristine NiCo2O4@NF, it was found that the doping of moderate amounts Fe3+ (x ≤ 1.0) would help to form the structure which can expose more active sites. Furthermore, XPS results indicate that transition from Co2+ to Co3+, the higher Co3+/Co2+ ratio contributes to good reducibility and oxygen mobility, and 3d state of Co3+ would generate strong hybridization with O 2p state. The EIS results imply that the incorporation of Fe can effectively improve the conductivity of materials and reduce the charge transfer resistance. Together with the magnetic properties, we found that Fe3+ ions replaced Co site in octahedral site with low spin state for x ≤ 1.0 implies beneficial effect for OER activity. While For x > 1.0, part of the Fe3+ ions locate in tetrahedron site with high spin state which show harmful effect for the OER activity.

Enhanced electrochemical oxygen generation from sillenite phase of bismuth iron oxide (Bi24Fe2O39) ultrafine particles stabilised at room temperature

Recently, lot of research is going on in development of clean energy-based technology to address the issue of exponentially increasing energy demands. Electrochemical water splitting is a clean and efficient process for generation of H2 and O2. Water electrolysis produces hydrogen and oxygen on cathode and anode respectively as separate half-cell reactions is one of the most important clean alternative processes. This work reports synthesis of Bi24Fe2O39 ultrafine crystalline nanoparticles via facile room temperature chemical method for the first time. Bi24Fe2O39 shows a spherical morphology with an average size of 8 nm. As obtained Bi24Fe2O39 acts as an electrocatalyst for electrochemical oxygen evolution reaction (OER). Electrochemical oxygen generation studies confirm the overpotential of 420 mV in 1 M KOH solution at a current density of 10 mA/cm2. Tafel slope and EIS studies give further insight of oxygen generation process. The results show that Bi24Fe2O39 exhibits low Tafel slope of 63 mV dec−1 and a very low charge transfer resistance of ∼10 Ω. This study paves a new way for future research into bismuth based sillenite structure for various energy related applications.

Construction of Heterojunction-Rich Metal Nitrides Porous Nanosheets Electrocatalyst for Alkaline Water/Seawater Splitting at Large Current Density.

The exploiting electrocatalysts for water/seawater electrolysis with remarkable activity and outstanding durability at industrial grade current density remains a huge challenge. Herein, CoMoNx and Fe-doped CoMoNx nanosheet arrays are in-situ grown on Ni foam, which possess plentiful holes, multilevel heterostructure, and lavish Co5.47N/MoN@NF and Fe-Co5.47N/MoN@NF interfaces. They require low overpotentials of 213 and 296mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline media to achieve current density of 800mA cm-2, respectively, and both possess low Tafel slopes (51.1 and 49.1mV dec-1) and undiminished stability over 80h. Moreover, the coupled Co5.47N/MoN@NF and Fe-Co5.47N/MoN@NF electrolyzer requires low voltages of 1.735V to yield 500mA cm-2 in alkaline water. Notably, they also exhibit exceptional electrocatalytic properties in alkaline seawater (1.833 V@500mA cm-2). The experimental studies and theoretical calculations verify that Fe doping does reduce the energy barrier from OH* to O* intermediates during OER process after catalyst reconstruction, and the non-metallic N site from MoN exhibits the lowest theoretical overpotential. The splendid catalytic performance is attributed to the optimized local electron configuration and porous structure. This discovery provides a new design method toward low-cost and excellent catalysts for water/seawater splitting to produce hydrogen.

2D MXene Ti3C2 Coupled with 1D Co3O4 Nanowires on Carbon Cloth for Efficient Chlorine Evolution Activity

AbstractChlorine evolution reaction (CER) is a key anode reaction in chlor‐alkali electrolysis. Although non‐precious metals have been widely used as CER catalysts, their low catalytic activity has been a major constraint on their development. Herein, 1D Co3O4 coupled with 2D Ti3C2 MXene on carbon cloth for highly efficient CER is reported by constructing two different heterojunctions (1D Co3O4 tip to 2D Ti3C2 face and 1D face to 2D face) through electronic coupling and strong interfacial interaction. The decreased electron density around O atoms in Co─O and Ti─O at two heterojunctions is more conducive to the adsorption of Cl−, thereby reducing the free energy of the reaction and jointly promoting CER. Consequently, the MXene@Co3O4/CC (carbon cloth) exhibits a low overpotential of 86 mV at 10 mA cm−1, low tafel slope of 47.9 mV dec−1, which is superior to commercial DSA and other non‐precious metal materials. This work provides new insights into the rational design of multiple heterojunctions, which leads to a new path for non‐precious metal catalysts in CER.

Hierarchical Porous Nonprecious High-entropy Alloys for Ultralow Overpotential in Hydrogen Evolution Reaction.

Water electrolysis is considered the cleanest method for hydrogen production. However, the widespread popularization of water splitting is limited by the high cost and scarce resources of efficient platinum group metals. Hence, it is imperative to develop an economical and high-performance electrocatalyst to improve the efficiency of hydrogen evolution reaction (HER). In this study, a hierarchical porous sandwich structure is fabricated through dealloying FeCoNiCuAl2Mn high-entropy alloy (HEA). This free-standing electrocatalyst shows outstanding HER performance with a very small overpotential of 9.7mV at 10 mA cm-2 and a low Tafel slope of 56.9 mV dec-1 in 1 M KOH solution, outperforming commercial Pt/C. Furthermore, this electrocatalytic system recorded excellent reaction stability over 100 h with a constant current density of 100 mA cm-2. The enhanced electrochemical activity in high-entropy alloys results from the cocktail effect, which is detected by density functional theory (DFT) calculation. Additionally, micron- and nano-sized pores formed during etching boost mass transfer, ensuring sustained electrocatalyst performance even at high current densities. This work provides a new insight for development in the commercial electrocatalysts for watersplitting.

Enhanced Photoelectrochemical Activity Realized from WS2 Thin Films Prepared by RF‐Magnetron Sputtering for Water Splitting

AbstractWe report the synthesis of tungsten sulfide (WS2) films using RF‐magnetron sputtering at different RF powers. X‐ray diffraction (XRD) data confirm the hexagonal crystal structure of WS2 with an average crystallite size of ∼44.54 Å. With increased RF power, the preferred orientation of WS2 crystallites shifts from (002) to (100). Linear sweep voltammetry (LSV) was used to assess the Photoelectrochemical (PEC) activity of WS2 films. The film deposited at 150 W demonstrated the highest photocurrent density of 5.44 mA/cm2. The 150 W film also showed a lower Tafel slope of ∼0.374 V/decade, indicating superior PEC activity. Mott Schottky's (MS) analysis revealed a notable shift in the flat band potential towards the negative side, suggesting a shifting of the Fermi level towards the conduction band. WS2 film grown at 150 W demonstrated a majority charge carrier density of 6.2×1021 cm−3 and a depletion layer width of 1.54 nm. The observed low charge transfer resistance of 155 Ω contributed to the enhanced PEC activity with a relaxation time constant of 37 ms. These properties suggest that WS2 can be suitable for PEC water splitting.

Fabrication and characterisation of CrMnFeCoNi high entropy alloy electrocatalyst for oxygen evolution reaction

Water electrolysis is attracting increasing attention in becoming the main method for green energy production, which has long been hindered by the sluggish kinetics of oxygen evolution reaction (OER) and high cost of noble-metal (NM) containing electrodes. Template replication technique has been employed to fabricate porous CrMnFeCoNi high entropy alloy (HEA) bulk foams with > 95 % porosity. High entropy led to the formation of a single-phase solid solution of transition metals in the as-fabricated porous HEA bulk foam, and the lattice distortion brings about the outstanding OER performance that is close to that of the RuO2 reference sample. Effective electrochemically active surface area and amount of exposed active sites are increased by grinding into nanoparticles, which produced superior OER performance with a near-record low overpotential of ∼ 245 mV to drive a current density of 10 mA/cm2, a low Tafel slope of 73.6 mV/dec, a double layer capacitance of 102.3 mF, and excellent long-term stability over 24 h. This work demonstrates a cost-effective way to fabricate NM-free HEA electrocatalyst with complex structure and excellent stability in OER, which could help in advancing the research for alkaline water electrolysis.

NiCoP fibers as novel catalysts for hydrogen evolution in alkali and acidic environment

NiCoP transition metal phosphide has been recognized as a most promising candidate to alternate the noble metals in hydrogen evolution reaction. Herein, it is first time presented the facile preparation of NiCoP electrocatalyst in form of fibers with dominant 1D structure formed by needle-less electrospinning technology and finalized by defined heat treatment process. The study provides a precise method for the preparation of NiCoP or similar phosphide fibers, together with an experimental proof of their excellent electrocatalytic performance in alkali and acidic environments. The as-prepared fibrous NiCoP electrocatalyst sintered in air at 900 °C followed by sintering at 700 °C in Ar/H2 exhibits low hydrogen evolution reaction overpotential (η10) of 141 mV in alkali and 146 mV in acidic environment corresponding with low Tafel slopes of 53 and 97.8 mV/dec, respectively. The bimetallic phosphide also shows superior oxygen evolution reaction activity in alkaline medium 1 M KOH with satisfying durability in long-term stability tests. The highly innovative fibrous form of the material not only plays a significant role in regulation of the electronic structure and boosting the electrochemical active sites and thus the electrocatalytic performance in water splitting technology, but also allows tuning of the electrode electric conductivity, occurrence of the active sites probability and thus utilisation of the electrode, together with its permeability and mechanical stability.

Nitrogen-doped carbon nanostructures embedded with Fe-Co-Cr alloy based nanoparticles as robust electrocatalysts for Zn-air batteries

Two types of nitrogen-doped carbon nanomaterials embedded with novel transition metal-based medium entropy alloy nanoparticles are synthesized via a simple, scalable, and cost-effective single-step pyrolysis route, by varying the stoichiometric ratio of iron and cobalt. The samples predominantly have bamboo-shaped nanotube morphology with some globular structures. The globules are core-shell type nanoparticles, i.e., containing the metallic-alloy nanoparticles encapsulated by the graphitic shell and embedded within defective amorphous-type carbon matrix. The electrochemical studies using these samples are conducted in basic medium to explore their potential for Zn-air batteries. Electrochemical measurements are carried out in 1 M and 0.1 M KOH, respectively, on a rotating disk electrode setup. The sample with higher cobalt content performs better for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) with regards to lower onset potential, lower Tafel slope and lower activation energy. However, the stability towards OER is better for the sample with higher iron content. The sample with higher cobalt content shows a better overall oxygen electrochemistry compared to the one with higher iron content, is at par with several state-of art electrocatalysts and is utilized for fabrication of a prototype Zn-air battery demonstrating its practical applicability.

Heterostructure of Fe-Doped CoMoOx/CoMoOx as an Efficient Electrocatalyst for Oxygen Evolution Reaction.

Oxygen evolution reaction (OER) plays a crucial role as a counter half-reaction for both electrochemical hydrogen production through water splitting and the generation of valuable carbon compounds via CO2 reduction. To overcome the sluggish kinetics of the OER, significant efforts have been devoted to developing cost-effective, sustainable, and efficient electrocatalysts, with transition-metal-based catalysts emerging as promising candidates. Herein, we successfully synthesized a core-shell type nanostructure of Fe-doped CoMoOx/CoMoOx (CMFO), which exhibits excellent electrocatalytic properties for OER. The presence of an amorphous layer of Fe-doped CoMoOx with abundant oxygen vacancies, along with the stability of a key OER intermediate, *O, contributes to the enhanced activity of CMFO catalyst compared to pristine CoMoOx (CMO). The optimized catalyst of CMFO-550 achieved much lower overpotential and Tafel slope and also exhibited better remarkable long-term stability for over 90 h compared to CMO-550. These findings highlight the potential of CMFO-550 as a cost-effective and highly efficient electrocatalyst for the OER. The successful development of this core-shell nanostructure opens up a new opportunity for the design and synthesis of advanced electrocatalysts for the OER, with implications for various applications in energy conversion and storage.

Carbon-coated Fe3O4@cotton fiber biomass carbon for the oxygen reduction reaction in air cathode microbial fuel cells

Iron-based oxide catalysts on biomass carbon fibers can jointly use their respective advantages of chemical composition and structure to develop catalysts for the oxygen reduction reaction (ORR). In this study, carbon-coated Fe3O4@cotton fiber biomass carbon (C@Fe3O4@CFBC) was prepared as an ORR catalyst through hydrothermal growth and calcination treatment for air cathode microbial fuel cells (MFCs). The carbon coating layer enhanced the O2 adsorption energy, decreased the overpotential, and promoted surface activation of the Fe3O4 catalyst. The carbon coating layer can modulate the surface electronic structure of the Fe3O4 catalyst with C–O–Fe bonding and improve the electrical conductivity to accumulate electrons on the Fe3O4 surface to enhance the ORR performance. The CFBC supported Fe3O4 nanoparticles to prevent severe aggregation and expose more effective surface-active sites. The C@Fe3O4@CFBC catalyst achieved a high positive half-wave potential (0.801 V) and low Tafel slope (73.7 mV·dec−1) compared with the Pt/C catalyst (0.877 V and 94.3 mV·dec−1). The assembled air cathode MFCs achieved a desirable maximum power density (1059 ± 16 mW·m−2) based on 1266 ± 94 mW·m−2 of Pt/C MFC devices. This work provides a strategy for designing highly active non-precious metal catalysts for air cathode MFCs.

Facile one-step solid-state synthesis of CuO nanoparticles finely decorated over carbon sheets for improved OER activity

Renewable energy storage and conversion in electrochemical fuel cells require highly efficient and cost-effective noble metal free electrocatalysts for oxygen evolution reaction (OER). Downscaling of a material to nanoscale morphology can lead to enhancement in its surface activities affecting its physical and chemical properties which can well serve the purpose. In lieu to this, it could be one of the first reports to tune the morphology of CuO particles to 10–25 nm finely trapped inside non-graphitic carbon sheets using a novel single step solid state reaction. XRD, SEM, TEM, XPS, and Raman analyses confirm the structural and morphological attributes. The synergistic effect from carbon and copper oxide resulted in the attainment of best-in-class electrode material for oxygen evolution reaction (OER). The as-prepared CuO/C shows an excellent OER activity with a low overpotential of 454 mV (vs. Ag/AgCl) at a current density of 10 mA cm−2 with a low Tafel slope of 74.9 mV dec−1. The amount of carbon is optimized to get optimal performance from the CuO nanopowder.

Energy storage and catalytic behaviour of cmWave assisted BZT and flexible electrospun BZT fibers for energy harvesting applications

High-performance lead-free Barium Zirconium Titanate (BZT) based ceramics have emerged as a potential candidate for applications in energy storage, catalysis for electro chemical energy conversion and energy harvesting devices as presented in this work. In the present study hybrid microwave sintered BZT are studied for dielectric, ferroelectric and phase transition properties. BZT ceramic exhibits tetragonal structure as confirmed by the Retvield refinement studies. XPS studies confirms the elemental composition of BZT and presence of Zr. Polarization versus electric field hysteresis loops confirms the ferroelectric behaviour of BZT ceramic. Encouragingly, the BZT showed a moderate energy storage efficiency of 30.7 % and relatively good electro chemical energy conversion (HER). Excellent catalytic activity observed for BZT electrode in acid medium with low Tafel slope 77 mV dec-1. Furthermore, electrospun nanofibers made of PVDF-HFP and BZT are used to make flexible piezoelectric nano generators (PENGs). FTIR studies show that the 16 wt% BZT composite ink exhibits a higher electroactive beta phase. The optimized open-circuit voltage and short circuit current of the flexible PENG exhibits 7Vpp and 750 nA under an applied force of 3N. Thus, flexible and self-powered BZT PENGs are alternative source of energy due to its reliability, affordability and environmental-friendly nature.

Regulating the Electronic Structure of Metal-Organic Frameworks by Introducing Mn for Enhanced Oxygen Evolution Activity.

The construction of low-cost and highly efficient oxygen evolution electrocatalysts is paramount for clean and sustainable hydrogen energy. In recent years, metal-organic framework (MOF) OER electrocatalysts have attracted tremendous research attention. Herein, we report a simple and facile strategy to construct bimetallic MOFs (named CoMn0.01) for enhancing OER catalytic performance. Significantly, CoMn0.01 exhibited remarkable OER activity (255 mV at 10 mA cm-2) and a low Tafel slope of 66 mV dec-1, superior to those of commercial benchmark electrocatalysts (RuO2, 352 mV, 178 mV dec-1). Besides, the catalyst demonstrated outstanding longevity for 144 h at a current density of 100 mA cm -2. Mn doping can regulate the electronic structure of Co MOFs, which optimizes charge transfer capability and improves conductivity.

Excellent Bifunctional Water Electrolysis Activities of α-MoO3/AC Nanocomposites

Electrocatalytic water splitting is a cost-effective and environment-friendly technique for producing oxygen and hydrogen through the oxygen/hydrogen evolution reaction (OER/HER). Developing the highly active and stable electrocatalyst, particularly for bifunctional water electrolysis (i.e., both OER and HER), is still a formidable challenge. Herein, we demonstrated the enhanced bifunctional water splitting activities by utilizing the molybdenum trioxide-anchored activated carbon (MoO3/AC) nanocomposites. The MoO3/AC samples were fabricated by the ultrasonication method using sol-gel synthesized MoO3 and biomass-derived AC, and they displayed a nanostreusel-like morphology with spherical MoO3 nanoparticle-decorated AC nanosheets. For the water electrolysis test, the MoO3/AC nanocomposites exhibited the excellent bifunctional electrocatalytic OER and HER performances with low overpotential and small Tafel slope values. Through analyzing the material characteristics and the electrochemical properties of MoO3/AC, it was found that the superb bifunctional OER-HER activities were attributed to the synergistic effects from the hybridization of highly conductive AC and electrochemically active α-MoO3. The results pronounce that the MoO3/AC nanocomposites possess an aptitude as a superb bifunctional OER/HER electrocatalyst for high-performance water electrolysis.

The catalytic activity of reduced graphene aerogel anchored with CoFe2O4 spinel via self-assembly technique for enhanced oxygen evolution reaction

The development of low-cost and highly active oxygen evolution reaction (OER) electrocatalysts is of significant importance for the advancement of sustainable new clean energy and storage systems. Herein, reduced graphene oxide (rGO) anchored with spinel CoFe2O4 (rGO/CoFe2O4) is prepared by hydrothermal synthesis, combined with freeze-drying and heat treatment processes. The effects of different spinel types, the loading amount of CoFe2O4 and heat treatment temperatures on the OER performance are investigated. The resulting possesses a typical mesoporous structure composed of CoFe2O4 nanoparticles with 20–50 nm and the lamellar rGO, leading to a large BET specific surface area. The as-prepared rGO/CoFe2O4 has an overpotential of 325 mV, a low Tafel slope (63.02 mV/dec) at a current density of 10 mA cm−2, and shows excellent stability with no significant current decay. Based on Density Functional Theory (DFT) calculations, the transition from *O to *OOH has the highest Gibbs free energy, which is the rate-determining step of the entire catalytic process. The Fe site on the (100) crystal plane of CoFe2O4 is most likely the reactive site for the OER process, improving the OER activity by decreasing the binding strength between the catalytic surface and adsorbed *O intermediates.

Construction of hierarchical CoNiMoOxHy/NF nanostructures for highly efficient urea oxidation reaction

Urea oxidation reaction (UOR) represents a promising alternative anodic reaction for saving the energy consumption of hydrogen production by water electrolysis, while its large-scale application is still hampered by UOR catalysts with unsatisfactory performance. Herein, a hierarchical self-standing CoNiMoOxHy/NF electrode is synthesized through a mild chemical etching and deposition process with ZIF-67 nanostructure grown on Ni foam as precursor. Electrocatalytic urea oxidation with CoNiMoOxHy/NF exhibits an outstanding activity with a quite low potential of 1.27 V (vs. RHE) at the benchmark current density of 10 mA cm−2. A low Tafel slope of 36 mV dec−1 indicates its superior reaction kinetics. By comparing with CoNiOxHy/NF, the enhanced activity is mainly attributed to the faster generation kinetics for active NiOOH species and more accessible active sites numbers. This work may provide a meaningful reference for design of high performance UOR catalysts.