High-efficiency Electrocatalysts Research Articles

Integrating CoP/Co heterojunction into nitrogen-doped carbon polyhedrons as electrocatalysts to promote polysulfides conversion in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have garnered extensive research interest as one of the most promising energy storage devices due to their ultra-high theoretical energy density. However, the sluggish reaction kinetics, abominable shuttling effect and inferior cycling stability severely restrict its practical application. Herein, a multifunctional CoP/Co@NC/CNT heterostructure host material was elaborately designed and synthesized by integrating CoP/Co heterojunction, N-doped carbon hollow polyhedrons (NC) and carbon nanotubes (CNTs). Specifically, the CoP/Co heterojunction can reconfigure the local electronic structure, resulting in a synergistic effect that enhances adsorption capacity and catalytic activity compared to CoP and Co alone. Furthermore, the CNTs-grafted NC not only provides multi-dimensional pathways for rapid electron transport and ion diffusion, but also physically restricts the diffusion of polysulfides during charge-discharge processes. Owing to these advantages, the battery assembled with the CoP/Co@NC/CNT/S cathode yields an impressive discharge specific capacity of 1479.9 mAh g−1 at 0.1C, and excellent capacity retention of 793.7 mAh g−1 over 500 cycles at 2C (∼85.5 % of initial capacity). The rational integration of multifunctional heterostructures could provide an effective strategy for designing high-efficiency nanocomposite electrocatalysts to promote sulfur redox kinetics in Li-S batteries.

Amorphous-Crystalline Heterostructured Nanoporous High-Entropy Alloys for High-Efficiency pH-Universal Water Splitting.

Developing high-efficiency durable electrocatalysts in wide pH range for water splitting is significant for environmentally-friendly synthesis of renewable hydrogen energy. Herein, a facile method by dealloying designable multicomponent metallic glass precursors is reported to synthesize amorphous-crystalline heterostructured nanoporous high-entropy alloys (AC-HEAs) of CuAgAuPtPd, CuAgAuIrRu, and CuAgAuPtPdIrRu, heaped up by nanocrystalline particles with an average size of 2-3nm and the amorphous glued phase. The synthesized AC-HEA-CuAgAuPtPd owns highly catalytic performances for hydrogen evolution reaction (HER), with 9.5 and 20mV to reach 10 mA·cm-2 in 0.5m H2SO4 and 1.0m KOH, and AC-HEA-CuAgAuIrRu delivers 208 and 200mV for oxygen evolution reaction (OER). Moreover, a two-electrode electrolyzer made of the AC-HEA-CuAgAuIrRu bifunctional electrodes exhibit a low cell voltage of 1.48 and 1.49V in the acidic and alkaline conditions at 10 mA·cm-2 for overall water splitting. Combining the enhanced catalytic activities from nanoscale amorphous structure and atom-level synergistic catalyst in AC-HEAs provides an effective pathway forpH-universal electrocatalysts of water splitting.

Cobalt-copper bimetallic selenides embedded in nitrogen-doped porous carbon nanocubes for diclofenac electrochemical sensing

Diclofenac (DCF) is a non-steroidal anti-inflammatory drug (NSAID), and its overuse poses a potential threat to human health and the aquatic environment, designing high-efficiency electrocatalysts for DCF detection is urgent. Herein, cobalt-copper bimetallic selenides embedded in nitrogen-doped porous carbon nanocubes (CoCuSe@NC) were elaborately designed via one-step in situ selenization of bimetallic CoCu-MOF. The chemical constituents and micromorphology of CoCuSe@NC composites can be further optimized by precisely regulating the selenization process and the doping ratio of bimetal in MOF precursor. As an electrocatalyst, CoCuSe@NC was proved to be highly efficient in electrochemical sensing of DCF with a broad linear range of 0.1-400 µmol/L and a detection limit of 0.024 µmol/L. This was attributed to the synergistic advantages between the heterogeneous structures, which produced more electrochemically active sites, effectively shortened the electron transport path, and improved electrocatalytic performance. Consequently, the constructed sensor exhibits high sensitivity, remarkable stability and applicability, and in particular can selectively detect DCF from other structurally similar coexisting analogs, resulting from the unique metal chelation ability. This work paves the way for designing effective bimetallic selenide electrocatalysts and exploring their applications in DCF electrochemical sensing.

Oxygen Functional Groups Regulate Cobalt-Porphyrin Molecular Electrocatalyst for Acidic H2O2 Electrosynthesis at Industrial-Level Current.

Electrosynthesis of hydrogen peroxide (H2O2) based on proton exchange membrane (PEM) reactor represents a promising approach to industrial-level H2O2 production, while it is hampered by the lack of high-efficiency electrocatalysts in acidic medium. Herein, we present a strategy for the specific oxygen functional group (OFG) regulation to promote the H2O2 selectivity up to 92 % in acid on cobalt-porphyrin molecular assembled with reduced graphene oxide. In situ X-ray adsorption spectroscopy, in situ Raman spectroscopy and Kelvin probe force microscopy combined with theoretical calculation unravel that different OFGs exert distinctive regulation effects on the electronic structure of Co center through either remote (carboxyl and epoxy) or vicinal (hydroxyl) interaction manners, thus leading to the opposite influences on the promotion in 2e- ORR selectivity. As a consequence, the PEM electrolyzer integrated with the optimized catalyst can continuously and stably produce the high-concentration of ca. 7 wt % pure H2O2 aqueous solution at 400 mA cm-2 over 200 h with a cell voltage as low as ca. 2.1 V, suggesting the application potential in industrial-scale H2O2 electrosynthesis.

Breaking the Passivation Effect for MnO2Catalysts in Li-S Batteries by Anion-Cation Doping.

Transition metal oxides (TMOs) are recognized as high-efficiency electrocatalyst systems for restraining the shuttle effect in lithium-sulfur (Li-S) batteries, owing to their robust adsorption capabilities for polysulfides. However, the sluggish catalytic conversion of Li2S redox and severe passivation effect of TMOs exacerbate polysulfide shuttling and reducethe cyclability of Li-S batteries, which significantly hinders the development of TMOs electrocatalysts. Here, through the anion-cation doping approach, dual incorporation of phosphorus and molybdenum into MnO2(P,Mo-MnO2) was engineered, demonstrating effective mitigation of the passivation effect and allowing for the simultaneous immobilization of polysulfides and rapid redox kinetics of Li2S.Both experimental and theoretical investigations reveal the pivotal role of dopants in fine-tuning the d-band center and optimizing the electronic structure of MnO2. Furthermore, this well-designed configuration processes catalytic selectivity. Specifically, P-doping expedites rapid Li2S nucleation kinetics by minimizing reaction-free energy, while Mo-doping facilitates robust Li2S dissolution kinetics by mitigating decomposition barriers.This dual-doping approach equips P,Mo-MnO2with robust bi-directional catalytic activity, effectively overcoming passivation effect and suppressing the notorious shuttle effect. Consequently, Li-S batteries incorporating P,Mo-MnO2-based separatorsdemonstrate favorable performance thanpristine TMOs. This design offers rational viewpoint for the development of catalytic materials with superior bi-directional sulfur electrocatalytic in Li-S batteries.

Oxygen-bridging Fe, Co dual-metal dimers boost reversible oxygen electrocatalysis for rechargeable Zn–air batteries

Rechargeable zinc-air batteries (ZABs) are regarded as a remarkably promising alternative to current lithium-ion batteries, addressing the requirements for large-scale high-energy storage. Nevertheless, the sluggish kinetics involving oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) hamper the widespread application of ZABs, necessitating the development of high-efficiency and durable bifunctional electrocatalysts. Here, we report oxygen atom-bridged Fe, Co dual-metal dimers (FeOCo-SAD), in which the active site Fe-O-Co-N6 moiety boosts exceptional reversible activity toward ORR and OER in alkaline electrolytes. Specifically, FeOCo-SAD achieves a half-wave potential (E1/2) of 0.87 V for ORR and an overpotential of 310 mV at a current density of 10 mA cm-2 for OER, with a potential gap (ΔE) of only 0.67 V. Meanwhile, FeOCo-SAD manifests high performance with a peak power density of 241.24 mW cm-2 in realistic rechargeable ZABs. Theoretical calculations demonstrate that the introduction of an oxygen bridge in the Fe, Co dimer induced charge spatial redistribution around Fe and Co atoms. This enhances the activation of oxygen and optimizes the adsorption/desorption dynamics of reaction intermediates. Consequently, energy barriers are effectively reduced, leading to a strong promotion of intrinsic activity toward ORR and OER. This work suggests that oxygen-bridging dual-metal dimers offer promising prospects for significantly enhancing the performance of reversible oxygen electrocatalysis and for creating innovative catalysts that exhibit synergistic effects and electronic states.

Sulfonated carbon dots modified IrO2 nanosheet as durable and high-efficient electrocatalyst for boosting acidic oxygen evolution reaction

Sulfonated carbon dots modified IrO2 nanosheet as durable and high-efficient electrocatalyst for boosting acidic oxygen evolution reaction

Trimetallic FeNiMo Nanofibers as High-Efficiency Electrocatalyst for Robust Oxygen Evolution

Trimetallic FeNiMo Nanofibers as High-Efficiency Electrocatalyst for Robust Oxygen Evolution

Novel FeNiP–FeNi–C nanofiber as an outstanding electrocatalyst for oxygen evolution reaction

Developing stable, highly active, and economical non-precious metal catalysts for the oxygen evolution reaction (OER) has been highly demanded in the new energy field since it can meet the industrial demands of large-scale electrocatalytic water splitting. A novel FeP/Ni2P/Fe0.64Ni0.36/C (FeNiP–FeNi–C) nanofiber was prepared by electrospinning and high-temperature phosphating. Notably, the good dispersion of FeP, Ni2P, and FeNi alloy nanoparticles in the nanocarbon fiber greatly increased the number of electroactive sites, and the synergistic effect between the FeP/Ni2P heterogeneous interface and FeNi alloy significantly improved the inherent activity of each site. Moreover, the carbon nanofibers enhanced the long-term durability of the catalyst by preventing the corrosion of the FeP, Ni2P, and FeNi alloy particles. Therefore, the optimal FeNiP–FeNi–C catalyst revealed exceptionally high OER activity, with overpotentials of 364 mV and 236 mV at 50 mA cm−2 and 10 mA cm−2 respectively, and the slope of Tafel of 61.00 mV·dec−1. This catalyst performs significantly better than commercial RuO2 catalysts in alkaline electrolytes. The results of this study offer a novel perspective for the mass production of non-precious metal OER high-efficiency electrocatalysts.

Transforming Cu into Cu2O/RuAl intermetallic heterojunction for lowering the thermodynamic energy barrier of the CO2 reduction and evolution reactions in Li–CO2 battery

The Li–CO2 battery has been under the spotlight of future battery technologies since it can achieve CO2 utilization and energy conversion simultaneously. However, its advancement is hampered by poor energy efficiency and limited reversibility due to the sluggish kinetics of the CO2 reduction and evolution reactions. Herein, a multiscale nanoporous interpenetrating‑phase nanohybrid of RuAl intermetallic and Cu2O (MP-Cu2O/RuAl) was carved by driving synchronous phase and microstructure evolutions through dealloying of one RuCuAl master alloy. The built-in RuAl intermetallic and Cu2O closely stack to form abundant nano-interfaces with revolutionized electronic structure. The theoretical simulations reveal that the Cu2O/RuAl interface can distinctly reduce the energy barrier of the Li2CO3 decomposition reaction. The interconnected pore channels with large surface area can enhance catalytic site accessibility, mass transfer, and uniform deposition of the discharge products. In situ differential electrochemical mass spectrometry discloses that the CO2-to-electron ratio during charging coincides with the theoretical value of 3/4, demonstrating the high efficacy of MP-Cu2O/RuAl in achieving the recycling of CO2. The dealloying protocol provides an affordable platform to empower transition metal oxides into high-efficiency electrocatalysts by hybridizing with metallic nano-sponge for advancing the application of Li–CO2 batteries.

Anion Modulation of Ag-Imidazole Cuboctahedral Cage Microenvironments for Efficient Electrocatalytic CO2 Reduction.

How to achieve CO2 electroreduction in high efficiency is a current challenge with the mechanism not well understood yet. The metal-organic cages with multiple metal sites, tunable active centers, and well-defined microenvironments may provide a promising catalyst model. Here, we report self-assembly of Ag4L4 type cuboctahedral cages from coordination dynamic Ag+ ion and triangular imidazolyl ligand 1,3,5-tris(1-benzylbenzimidazol-2-yl) benzene (Ag-MOC-X, X=NO3, ClO4, BF4) via anion template effect. Notably, Ag-MOC-NO3 achieves the highest CO faradaic efficiency in pH-universal electrolytes of 86.1 % (acidic), 94.1 % (neutral) and 95.3 % (alkaline), much higher than those of Ag-MOC-ClO4 and Ag-MOC-BF4 with just different counter anions. In situ attenuated total reflection Fourier transform infrared spectroscopy observes formation of vital intermediate *COOH for CO2-to-CO conversion. The density functional theory calculations suggest that the adsorption of CO2 on unsaturated Ag-site is stabilized by C-H⋅⋅⋅O hydrogen-bonding of CO2 in a microenvironment surrounded by three benzimidazole rings, and the activation of CO2 is dependent on the coordination dynamics of Ag-centers modulated by the hosted anions through Ag⋅⋅⋅X interactions. This work offers a supramolecular electrocatalytic strategy based on Ag-coordination geometry and host-guest interaction regulation of MOCs as high-efficient electrocatalysts for CO2 reduction to CO which is a key intermediate in chemical industry process.

Improved Urea Oxidation Performance via Interface Electron Redistributions of the NiFe(OH)x/MnO2/NF p-p Heterojunction.

The development of highly efficient urea oxidation reaction (UOR) electrocatalysts is the key to simultaneously achieving green hydrogen production and the treatment of urea-containing wastewater. Ni-based electrocatalysts are expected to replace precious metal catalysts for UOR because of their high activity and low cost. However, the construction of Ni-based electrocatalysts that can synergistically enhance UOR still needs further in-depth study. In this study, highly active electrocatalysts of NiFe(OH)x/MnO2 p-p heterostructures are constructed on nickelfoam (NF) by electrodeposition (NiFe(OH)x/MnO2/NF), illustrating the effect of electronic structure changes at heterogeneous interfaces on UOR and revealing the catalytic mechanism of UOR. The NiFe(OH)x/MnO2/NF only needs 1.364V (vs Reversible Hydrogen Electrode, RHE) to reach 10mA cm-2 for UOR. Structural characterizations and theoretical calculations indicate that energy gap leads to directed charge transfer and redistribution at the heterojunction interface, forming electron-rich (MnO2) and electron-poor (NiFe(OH)x) regions. This enhances the catalyst's adsorption of urea and reaction intermediates, reduces thermodynamic barriers during the UOR process, promotes the formation of Ni3+ phases at lower potentials, and thus improves UOR performance. This work provides a new idea for the development of Ni-based high-efficiency UOR electrocatalysts.

Highly efficient electrochemical ascorbic acid determination via a cooperative catalytic effect of dendritic Bi/Bi2O3 junctions and oxygen vacancies

This study developed an electrochemical sensor for ascorbic acid (AA) using dendritic nanostructured (DN) bismuth/bismuth oxide thin films with oxygen-deficient (SOD) surfaces (SOD-DN Bi/Bi2O3-x thin films) that were successfully fabricated through electrodeposition on fluorine-doped tin oxide (FTO) substrates. Using cyclic voltammetry and amperometry, we assessed electrocatalytic activity in neutral media. The prepared SOD-DN Bi/Bi2O3-x thin film was used, for the first time, as electrodes in a highly sensitive and selective electrochemical AA sensor. The SOD-DN Bi/Bi2O3-x thin film with optimal characteristics was shown to be ultrasensitive in AA detection in neutral conditions, whereby high detection sensitivity ∼ 2.30 µA µM-1cm−2 over a wide range of AA concentration ∼ 0.01 µM to 1.0 mM and working potential range ∼ 0.3–1.0 V vs. SCE. The results indicate that SOD-DN Bi/Bi2O3-x can provide large amounts of active reaction sites, thereby enhancing electrocatalytic activity and electrochemical sensitivity. Due to this, it is a unique electrochemical sensor able to detect AA without interference from DA, UA, or other contaminants. A further amperometric test demonstrated that this sensor was capable of detecting AA even under conditions of dopamine and uric acid. Accordingly, the proposed sensor provides a promising avenue for developing electrochemical sensing for AA determination. This strategy introduces a novel type of high-efficiency electrocatalyst for ultrasensitive detection of medical and environmental biomarkers.

Nanocluster-agminated amorphous cobalt nanofilms for highly selective electroreduction of nitrate to ammonia

Developing highly-efficient electrocatalysts for the nitrate reduction reaction (NITRR) is a persistent challenge. Here, we present the successful synthesis of 14 amorphous/low crystallinity metal nanofilms on three-dimensional carbon fibers (M-NFs/CP), including Al, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, In, Sn, Pb, Au, or Bi, using rapid thermal evaporation. Among these samples, our study identifies the amorphous Co nanofilm with fine agglomerated Co clusters as the optimal electrocatalyst for NITRR in a neutral medium. The resulting Co-NFs/CP exhibits a remarkable Faradaic efficiency (FENH3) of 91.15 % at − 0.9 V vs RHE, surpassing commercial Co foil (39 %) and Co powder (20 %), despite sharing the same metal composition. Furthermore, during the electrochemical NITRR, the key intermediates on the surface of the Co-NFs/CP catalyst were detected by in situ Fourier-transform infrared (FTIR) spectroscopy, and the possible reaction ways were probed by Density functional theory (DFT) calculations. Theoretical calculations illustrate that the abundant low-coordinate Co atoms of Co-NFs/CP could enhances the adsorption of *NO3 intermediates compared to crystalline Co. Additionally, the amorphous Co structure lowers the energy barrier for the rate-determining step (*NH2→*NH3). This work opens a new avenue for the controllable synthesis of amorphous/low crystallinity metal nano-catalysts for various electrocatalysis reaction applications.

Cobalt-based selenide composite materials as high-efficiency electrocatalysts for oxygen evolution reaction

Water electrolysis serves as a crucial pathway for the generation of renewable hydrogen energy, with the oxygen evolution reaction (OER) demanding more energy compared to the hydrogen evolution reaction (HER). Consequently, we prepared cobalt-based selenide composite materials (CS/XC-Ni) through chemical doping and heterojunction construction. CS/XC-Ni demonstrated outstanding OER performance when exposed to alkaline electrolytes. Specifically, at a current density of 10 mA·cm−2, the overpotential was 334 mV, and the overpotential at a current density of 50 mA·cm−2 was 435 mV, with a Tafel slope of 94 mV·dec−1. Density functional theory (DFT) calculations indicate that the introduction of Ni optimizes the catalyst's O adsorption capability, while the construction of heterogeneous interfaces reduces the energy barrier of the rate-determining step. This demonstrates the great potential of Co/XC-Ni in oxygen evolution, providing new insights for the design and synthesis of efficient oxygen evolution catalysts.

Computational design of two-dimensional transition metal supported biphenylene as efficient electrocatalysts toward nitrogen reduction reaction

Electrochemical nitrogen reduction reaction (eNRR) at standard conditions shows promise as an innovative approach for artificial nitrogen fixation, potentially offering a more energy-efficient alternative to the Haber-Bosch method. Design and evolution of low-cost and high-efficiency electrocatalysts remain the significant challenge confronting eNRR. Single-atom catalysts have recently been intensively explored due to their 100% utilization, high activity, and high selectivity. Here, a series of transition metal atom anchored on biphenylene (TM−BPN, TM = Sc−Hg) are studied as electrocatalysts (SACs) for eNRR by density functional theory computation. Among them, 19 SACs are screened out as the most promising electrocatalyst with lower limiting potential than that on the stepped Ru (0001). The Re−BPN catalyst exhibits the highest catalytic activity with a lowest limiting potential of -0.48 V. In addition, the Re−BPN also exhibits high eNRR selectivity by suppressing the competing hydrogen evolution reaction with the Faradaic efficiency being ∼100%. Partial density of states and Bader charge analysis illuminate the origin of eNRR catalytic activity of TM−BPN. Furthermore, the SAC structure remains intact under 500 K with no bond breaking. This study deepens our insight into the utilization of SACs in N2 fixation, contributing significantly to the exploration of efficient electrocatalysts for eNRR.

Synergistic enhancement of oxygen vacancy enrichment and morphology regulation in CeO2-NiCo2O4 heterostructure catalysts for high-performance cathodes in direct borohydride-hydrogen peroxide fuel cells

Hydrogen peroxide (H2O2) emerges as a viable oxidant for fuel cells, necessitating the development of an efficient and cost-effective electrocatalyst for the hydrogen peroxide reduction reaction (HPRR). In this study, we synthesized a self-supporting, highly active HPRR electrocatalyst comprising two morphologically distinct components: CeO2-NiCo2O4 nanowires and CeO2-NiCo2O4 metal organic framework derivatives, via a two-step hydrothermal process followed by air calcination. X-ray diffraction and transmission electron microscopy analysis confirmed the presence of CeO2 and NiCo2O4, revealing the amalgamated interface between them. CeO2 exhibits multifunctionality in regulating the surface electronic configuration of NiCo2O4, fostering synergistic connections, and introducing oxygen deficiencies to enhance the catalytic efficacy in HPRR. Electrochemical measurements demonstrate a reduction current density of 789.9 mA·cm−2 at −0.8 V vs. Ag/AgCl. The assembly of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) exhibits a peak power density of 45.2 mW·cm−2, demonstrating durable stability over a continuous operation period of 120 h. This investigation providing evidence that the fabrication of heterostructured catalysts based on CeO2 for HPRR is a viable approach for the development of high-efficiency electrocatalysts in fuel cell technology.

One-step fabrication of P-Co5.47N/Co9S8@NPC heterojunction derived from saccharomycetes cerevisiae as environment-friendly bifunctional high-efficiency electrocatalysts

The one-step green preparation of heterojunction-structured bifunctional high-efficiency electrocatalysts provides a simple method for the green, low-cost, convenient and efficient application of hydrogen energy, meanwhile it is still challenging to achieve. In the present work, the phosphorus-doped two-phase heterojunction P-Co5.47N/Co9S8@NPC nanorods was synthesized on carbon cloth (CC) as a high-quality bifunctional electrode through simple one-step chemical vapor deposition (CVD) method. Saccharomycetes cerevisiae were used for the non-toxic phosphorus doping and formation of a carbon nanolayer wrapping Co5.47N/Co9S8 nanorods. Compared with the single-phase electrocatalyst Co9S8@NPC NSs/CC, P-Co5.47N/Co9S8@NPC NSs/CC exhibited more excellent electrocatalytic performance which required overpotentials of 69 mV for hydrogen evolution reaction (HER), 182.5 mV for oxygen evolution reaction (OER), 1.45 V for over water splitting (OWS) at 10 mA cm−2 in KOH solution. The designed P-Co5.47N/Co9S8@NPC NSs/CC presented multiple advantages of nanorod structure, doped structure, abundant heterointerfaces, as well as dual-phase synergy, which triggered outstanding electrocatalytic performance.

Promoting Oxygen Evolution Electrocatalysis by Coordination Engineering in Cobalt Phosphate.

Understanding the structure-activity correlation is an important prerequisite for the rational design of high-efficiency electrocatalysts at the atomic level. However, the effect of coordination environment on electrocatalytic oxygen evolution reaction (OER) remains enigmatic. In this work, the regulation of proton transfer involved in water oxidation by coordination engineering based on Co3(PO4)2 and CoHPO4 is reported. The HPO4 2- anion has intermediate pKa value between Co(II)-H2O and Co(III)-H2O to be served as an appealing proton-coupled electron transfer (PCET) induction group. From theoretical calculations, the pH-dependent OER properties, deuterium kinetic isotope effects, operando electrochemical impedance spectroscopy (EIS) and Raman studies, the CoHPO4 catalyst beneficially reduces the energy barrier of proton hopping and modulates the formation energy of high-valent Co species, thereby enhancing OER activity. This work demonstrates a promising strategy that involves tuning the local coordination environment to optimize PCET steps and electrocatalytic activities for electrochemical applications. In addition, the designed system offers a motif to understand the structure-efficiency relationship from those amino-acid residue with proton buffer ability in natural photosynthesis.

General and Facile Synthesis of Co/CoO Nanoparticals Supported by Nitrogen-Doped Graphenic Networks as Efficient Oxygen Electrocatalyst for Zn-Air Batteries.

Reasonable design of low-cost, high-efficiency and stable bifunctional oxygen electrocatalysts is of great significance to improve the reaction efficiency of Zn-air batteries, which is still a huge challenge. Here, we report a highly efficient bifunctional oxygen electrocatalyst with three-dimensional (3D) N-doped graphene network-supported cobalt and cobalt oxide nanoparticles (Co/CoO-NG), which can be in situ synthesized by inducing metal ions on metal plates via graphene oxide as an inducer. This 3D network structure and open active center show excellent bifunctional oxygen electrocatalytic activity under alkaline conditions, and can be used as an air electrode in rechargeable Zn-air batteries, with significantly better power density (244.28 mW cm-2) and stability (over 340 h) than commercial Pt/C+RuO2 mixtures. This work is conducive to advancing the practical application of graphene-based materials as air electrodes for rechargeable zinc-air batteries.