Co2P nanoparticles supported on cobalt-embedded N-doped carbon materials as a bifunctional electrocatalyst for rechargeable Zn-air batteries

Reversible oxygen electrodes with high efficiencies for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great significance for a variety of energy conversion devices, such as fuel cells and metal-air batteries. Herein, Co₂P nanoparticles supported on cobalt-embedded N-doped carbon materials (Co₂P/Co–N–C) have been prepared by pyrolysis of cobalt zeolitic imidazolate framework and phosphating post treatment. The optimal Co₂P/Co–N–C composite shows excellent bifunctional electrocatalytic activities for both OER (the potential of 1.65 V at 10 mA cm^?2) and ORR (half-wave potential of 0.82 V). As a practical demonstration, Co₂P/Co–N–C catalyst is used as an air electrode in liquid Zn-air battery, which displays a large open-circuit voltage of 1.50 V, a high peak-power density of 158 mW cm^?2 and excellent reversibility of over 205 h at 5 mA cm^?2. Moreover, the flexible Zn-air battery with Co₂P/Co–N–C exhibits a high open-circuit voltage of 1.46 V and the good flexibility with different angles. This work provides inspiration to explore new strategies for electrochemical energy conversion and storage.     

Metal-organic framework derived Co@NC/CNT hybrid as a multifunctional electrocatalyst for hydrogen and oxygen evolution reaction and oxygen reduction reaction

Seeking a multifunctional electrocatalyst composed of earth-abundant elements for highly hydrogen and oxygen evolution reaction and oxygen reduction reaction (HER, OER and ORR) is technically imperative for the electrocatalytic applications. Herein, we report HER, OER and ORR electrocatalytic performances of metal-organic framework (MOF) derived cobalt nanoparticles encapsulated in nitrogen-doped carbon and carbon nanotube (Co@NC/CNT). The optimized Co@NC/CNT hybrid shows superior HER and OER activities with a small overpotential of 137 mV and 302 mV at a current density of 10 mA cm⁻², respectively. Furthermore, the Co@NC/CNT as an air-cathode in secondary Zn-air battery demonstrates a confined potential gap of 0.88 V over 200 h and a maximum power density of 53.4 mW cm⁻², which are much better than those of Pt/C. The outstanding performances are attributed to the synergistic effects from Co, and N embedded into carbon and CNT. More importantly, the unique surface structure contributes to expose many active sites for superior catalytic activity through allowing a large number of electrons. These outcomes not only prove a facile approach for the preparation of metals/carbon hybrid but also disclose its huge possible as a multifunctional electrocatalyst for sustainable energy systems.     

Tunable Fe/N co-doped 3D porous graphene with high density Fe-Nx sites as the efficient bifunctional oxygen electrocatalyst for Zn-air batteries

Nitrogen-doped transition metal materials display promising potential as bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Fe/N co-doped three-dimensional (3D) porous graphene (FeN-3D-PG) is prepared via a template method using sodium alginate as the carbon source and low polymerization degree melamine resin as the nitrogen source. The low polymerization degree melamine resin can form complexes with Fe³⁺ in the aqueous solution and further forms high density Fe-N_x active sites during pyrolysis. Meanwhile, the formed 3D porous structure efficiently promotes the uniform distribution of Fe-N_x active sites. The FeN-3D-PG catalyst exhibits pH-independent ORR activity. For OER, the catalyst possesses a low over potential (370 mV at 10 mA cm⁻²) in alkaline electrolyte. The Zn-air batteries (ZABs) using FeN-3D-PG as cathode exhibits a power density up to 212 mW cm⁻², a high specific capacity of 651 mAh g⁻¹, and the charge-discharge stability of 80 h. This work provides new sight to transition metal materials based ZABs with excellent performance.     

Covalent organic polymer derived N–doped carbon confined FeNi alloys as bifunctional oxygen electrocatalyst for rechargeable zinc-air battery

N–doped carbon confined FeNi alloys are promising candidate to noble Pt and IrO₂ or RuO₂ for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable zinc-air batteries. However, it is difficult to control the distribution of transition metals in the precursor and electrocatalyst. Herein, we design a covalent organic polymer to realize the uniform distribution of metal, nitrogen and carbon precursors. The structure of the obtained electrocatalyst is FeNi nanoparticles coated with carbon shells dispersed on N-doped multilayer porous carbon (FeNi@NC). The resultant FeNi@NC delivered a half-wave potential for ORR of 0.878 V and a low potential of 1.59 V to achieve 10 mA cm^?2 for OER, which surpasses commercial platinum/carbon and ruthenium dioxide. The outstanding bifunctional properties of FeNi@NC attribute to the synergistic coupling between N-doped carbon shells and dense FeNi nanoparticles. Moreover, the self-made zinc-air battery with FeNi@NC air-cathode displayed an excellent energy density of 137.7 mW cm^?2 as well as cycling stability (100 h, 200 cycles).     

Hollow NH2-MIL-101@TA derived electrocatalyst for enhanced oxygen reduction reaction and oxygen evolution reaction

Non-precious metal-based electrocatalysts with excellent activity and stability are highly desired for the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, a tannic acid (TA) etching strategy is used to inhibit the metal aggregation and achieve muti-metal doping. The hollow NH₂-MIL-101@TA derived Fe–N–C catalyst exhibits superior ORR catalytic activity with an E_1/2 of 0.872 V and a maximum output power density of 123.4 mW cm⁻² in Zn-air battery. Since TA can easily chelate with metal ions, Fe/Co–N–C and Fe/Ni–N–C are also synthesized. Fe/Ni–N–C manifests exceptional bifunctional activity with an E_j = 10 of 1.67 V and a potential gap of 0.833 V between E_j = 10 and E_1/2 in alkaline electrolyte, which is 45 mV smaller than Pt/C–IrO₂. The improvement of ORR and OER performance of the catalysts via the simple TA etching and chelation method provides a novel strategy for the design and synthesis of efficient electrocatalysts.     

Effect of iron on Ni–Mo–Fe composite as a low-cost bifunctional electrocatalyst for overall water splitting

By increasing demand for hydrogen and oxygen gas for energy and industrial applications, designing a cheap, high-efficiency, and bifunctional electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) seems necessary. For this purpose Ni–Mo–Fe as a bifunctional electrocatalyst was synthesized by one-step electrodeposition. From this electrocatalyst with optimal composition and current density, a small overpotential of 65, 161 mV for delivering 10, 100 mA/cm² on HER in alkaline media was achieved. As-fabricated electrode exhibited 344,408 mV for delivering 10, 100 mA/cm² in OER. Furthermore, this electrocatalyst shows high stability and negligible degradation in overpotential for HER and OER under long term stability tests in alkaline media. The notable function of As-fabricated Ni–Mo–Fe is due to the synergism effect between Ni, Mo, and Fe element and binder-free structure. Owing to the high-performance and high-stability of Ni–Mo–Fe electrocatalyst under Hydrogen and Oxygen evolution reactions is a candidate for industrial uses in the alkaline electrolyzer.     

Transitional metal alloyed nanoparticles entrapped into the highly porous N-doped 3D honeycombed carbon: A high-efficiency bifunctional oxygen electrocatalyst for boosting rechargeable Zn-air batteries

Rational development of low-cost, durable and high-performance bifunctional oxygen catalysts is highly crucial for metal-air batteries. Herein, transition metal alloyed FeCo nanoparticles (NPs) embedded into N-doped honeycombed carbon (FeCo@N-HC) was efficiently prepared by a one-step carbonization method in the existence of NH₄Cl and citric acid. Benefiting from the honeycomb-like architectures and the synergistic effects of the FeCo alloy with the doped-carbon matrix, the as-synthesized FeCo@N-HC exhibited outstanding oxygen reduction reaction (ORR) with the more positive onset potential (E_onset = 0.98 V vs. RHE) and half-wave potential (E_1/2 = 0.85 V vs. RHE), coupled with outstanding oxygen evolution reaction (OER) with the lower overpotential (318 mV) at 10 mA cm^?2. Besides, the home-made Zn-air battery has the larger power density of 144 mW cm^?2 than Pt/C + RuO₂ (80 mW cm^?2). This research offers some valuable guidelines for constructing robust oxygen catalysts in clean energy storage and conversion technologies.     

Amino functionalized carbon nanotubes supported CoNi@CoO–NiO core/shell nanoparticles as highly efficient bifunctional catalyst for rechargeable Zn-air batteries

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the core reaction processes of rechargeable Zn-air battery (ZAB) cathode. Therefore, exploring a bifunctional catalyst with excellent electrochemical performance, high durability, and low cost is essential for rechargeable ZAB. In this work, amino functionalized carbon nanotubes supported core/shell nanoparticles composed of CoNi alloy core and CoO–NiO shell (CoNi@CoO–NiO/NH₂-CNTs-1) is synthesized through a simple and efficient hydrothermal reaction and calcination method, which shows higher ORR/OER bifunctional catalytic performance than the single metal-based catalyst, such as Ni@NiO/NH₂-CNTs and Co@CoO/NH₂-CNTs. The fabricated bimetallic alloy based catalyst CoNi@CoO–NiO/NH₂-CNTs-3 with the optimized loading content of CoNi@CoO–NiO core/shell nanoparticles, presents the best bifunctional catalytic performance for ORR/OER. Experimental studies reveal that CoNi@CoO–NiO/NH₂-CNTs-3 exhibits the onset potential of 0.956 V and 1.423 V vs. RHE for ORR and OER, respectively. It also exhibits a low overpotential of 377 mV to achieve a 10 mA cm^?2 current density for OER, and positive half-wave potentials of 0.794 V for ORR. And the potential difference between half-wave potential of ORR (E_1/2) and the potential at 10 mA cm^?2 for OER (E_j10) is 0.813 V. In addition, when CoNi@CoO–NiO/NH₂-CNTs-3 is used as an air electrode catalyst of rechargeable ZAB, its maximum power density and open circuit voltage (OCV) can reach 128.7 mW cm^?2 and 1.458 V (The commercially available catalyst of Pt/C–RuO₂ is 88.1 mW cm^?2), which strongly demonstrates that the fabricated catalyst CoNi@CoO–NiO/NH₂-CNTs-3 can be used as a highly efficient bifunctional catalyst for ZABs, and is expected to replace those expensive precious metal electrocatalysts to meet the growing demand for new energy devices.     

Boron doping induced electronic reconfiguration of Fe-Nx sites in N-doped carbon matrix for efficient oxygen reduction reaction in both alkaline and acidic media

Developing non-precious metal-based catalysts as the substitution of precious catalysts (Pt/C) in oxygen reduction reaction (ORR) is crucial for energy devices. Herein, a template and organic solvent-free method was adopted to synthesize Fe, B, and N doped nanoflake-like carbon materials (Fe/B/N–C) by pyrolysis of monoclinic ZIF-8 coated with iron precursors and boric acid. Benefiting from introducing B into Fe–N–C, the regulated electron cloud density of Fe-N_x sites enhance the charge transfer and promotes the ORR process. The as-synthesized Fe/B/N–C electrocatalyst shows excellent ORR activity of a half-wave potential (0.90 V vs 0.87 V of Pt/C), together with superior long-term stability (95.5% current density retention after 27 h) in alkaline media and is even comparable to the commercial Pt/C catalyst (with a half-wave potential of 0.74 V vs 0.82 V of Pt/C) in an acidic electrolyte. A Zn-air battery assembled with Fe/B/N–C as ORR catalyst delivers a higher open-circuit potential (1.47 V), specific capacity (759.9 mA h g^?1_Zn at 10 mA cm^?2), peak power density (62 mW cm^?2), as well as excellent durability (5 mA cm^?2 for more than 160 h) compared to those with commercial Pt/C. This work provides an effective strategy to construct B doped Fe–N–C materials as nonprecious ORR catalyst. Theoretical calculations indicate that introduction of B could induce Fe-N_x species electronic configuration and is favorable for activation of OH1 intermediates to promote ORR process.     

Tailoring Cr doped NiFeP nanoparticles embedded in 3D cellulose nanofibrils carbon architecture for efficient oxygen evolution reaction

Oxygen evolution reaction (OER) is considered the bottleneck that restricting the pace of electrocatalytic hydrogen production. Modulating structure and heterogeneous doping are essential approaches to effectively promote the electrocatalytic efficiency and stability. Herein, three-dimensional (3D) porous Cr doped NiFeP nanoparticles encapsulated in cellulose nanofibrils (CNF) carbon architecture (Cr–NiFeP/NC) with high-efficiency and durable OER performance was constructed. CNF played crucial role on the construction of 3D porous framework and promoting the OER performance significantly. Benefiting from the 3D porous structure, high specific surface area and exposed abundant active sites, the Cr–NiFeP/NC electrocatalyst displayed excellent OER performance, which the overpotential to deliver the current density of 10 mA cm⁻² was only 249 mV with a Tafel slope of 51.2 mV dec⁻¹ in 1.0 M KOH, outperforming the RuO₂ and other reported electrocatalysts remarkably. In addition, the Cr–NiFeP/NC electrocatalyst exhibited outstanding stability, which the overpotential was only increased by 2.5% after 48 h chronopotential measurement to deliver a current density of 10 mA cm⁻² with stable morphology and structure. This work demonstrated an integrated strategy of Cr doping and 3D porous structure modulating employed CNF as skeleton for the efficient and durable OER performance, providing a spark for hydrogen production by water splitting.     

Controllable synthesis of Co/MnO heterointerfaces embedded in graphitic carbon for rechargeable Zn–air battery

Owing to the unique geometric and electronic structure, design and synthesis of electrocatalysts with well defined heterointerfaces are essential for clean energy technologies, for instance water-splitting and Zn-air batteries. Herein, a bifunctional electrocatalyst assembled by Co/MnO nanoparticles and nitrogen doping double-sphere carbon (denoted as Co/MnO@N-DSC), was fabricated via a solvothermal and pyrolysis strategy. The Co/MnO@N-DSC catalysts exhibit an enhanced bifunctional oxygen electrocatalytic performance for Oxygen reduction reaction (ORR) (E_1/2, 0.84 V vs. RHE) and oxygen evolution reaction (OER) (E_onset, 1.54 V vs. RHE). As an air cathode catalyst, the Co/MnO@N-DSC-based Zn-air battery can afford prime performance, over the commercial noble-metal-based Zn-air battery. Theoretical calculation results indicate that the synergism of Co (111)/MnO (200) heterointerfaces can enhance charge transfer and provide extra electrons for the reaction processes. This work provides a promising manoeuvre to uplift bifunctional catalytic activity by increasing the synergy from heterointerfaces of transition-metal/metal oxide in oxygen electrocatalysis.     

MoS2/NiS heterostructure grown on Nickel Foam as highly efficient bifunctional electrocatalyst for overall water splitting

It is great important to develop and explore a non-precious bifunctional electrocatalyst with high efficiency and good stability for Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) in alkaline electrolyte. Herein, a three-dimensional (3D) needle-like MoS₂/NiS heterostructure supported on Nickel Foam (NF) (MoS₂/NiS/NF) is synthesized by a simple hydrothermal method for the first time, which can act as a good bifunctional electrocatalyst for overall water splitting. As expected, the optimal MoS₂/NiS/NF exhibits excellent catalytic performance with a low overpotential of 87 and 216 mV at 10 mA cm⁻² for HER and OER in 1 M KOH electrolyte, respectively, accompanied by good cycle stability. Furthermore, the MoS₂/NiS/NF as bifunctional electrocatalyst in an electrolyzer shows high efficiency with a cell voltage of 1.5 V at 10 mA cm⁻², as well as superior durability. The present work may open a new direction to design and develop a non-precious bifunctional electrocatalyst with excellent catalytic activity for water splitting in the future.     

Bimetallic metal-organic framework derived electrocatalyst for efficient overall water splitting

The development of bifunctional catalysts that can be applied to both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is widely regarded as a key factor in the production of sustainable hydrogen fuel by electrochemical water splitting. In this work, we present a high-performance electrocatalyst based on nickel-cobalt metal-organic frameworks for overall water splitting. The as-obtained catalyst shows low overpotential to reaches the current density of 10 mA cm⁻² with 249 mV for OER and 143 mV for HER in alkaline media, respectively. More importantly, when the electrolyzer was assembled with the as-prepared catalyst as anode and cathode simultaneously, it demonstrates excellent activity just applies a potential of 1.68 V to achieve 10 mA cm⁻² current density for overall water splitting.     

Self-supported hierarchical porous FeNiCo-based amorphous alloys as high-efficiency bifunctional electrocatalysts toward overall water splitting

Rationally designing an efficient and cost-effective bifunctional electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is a primary matter in applying electrocatalytic water splitting. Herein, a self-supported FeNiCo-based amorphous catalyst with a hierarchical micro/nanoporous structure is fabricated by dealloying an amorphous/nanocrystalline precursor. The amorphous nanoporous framework enables the prepared electrocatalyst to afford fast reaction kinetics, abundant active sites, and enhanced electrochemical active surface areas (ECSAs). Such structural advantages and the synergistic effects of the ternary transition metals contribute to a dramatic catalytic activity of this electrocatalyst under alkaline conditions, which delivers the current density of 10 mA cm⁻² at a low overpotential of 134 mV for HER and 206 mV for OER, respectively. Furthermore, a full electrolysis apparatus constructed by the self-supported hierarchical micro/nanoporous FeNiCo-based amorphous electrocatalyst as both cathode and anode acquires a dramatically low voltage of 1.58 V operating at 10 mA cm⁻² along with stability for more than 24 h for overall water splitting.     

Co-based MOF-derived Co/CoN/Co2P ternary composite embedded in N- and P-doped carbon as bifunctional nanocatalysts for efficient overall water splitting

In this work, we developed ternary metallic cobalt-cobalt nitride-dicobalt phosphide composite embedded in nitrogen and phosphorus co-doped carbon (Co/CoN/Co₂P-NPC) as bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The as-prepared Co/CoN/Co₂P-NPC is achieved by simultaneous annealing and phosphating of a Co–N rich metal-organic frameworks (MOFs) precursor. Compare with the phosphorus-free Co/CoN embedded nitrogen-doped carbon electrocatalyst (Co/CoN-NC), the as-prepared Co/CoN/Co₂P-NPC display superior HER and OER low overpotential of 99 mV and 272 mV at current density of 10 mA cm⁻². When Co/CoN/Co₂P-NPC electrocatalyst is use as bifunctional catalysts in overall alkaline water splitting, it exhibit excellent behaviour with 10 mA cm⁻² current at overall cell potential of 1.60 V. The excellent performance of Co/CoN/Co₂P-NPC electrocatalyst is attributed to the phosphating process that could further enhance synergistic effect, create stronger electronic interactions, and form efficient dual heteroatom doping to optimize the interfacial adhesion within the electrocatalyst. This present work will create more opportunities for the development of new, promising and more active sites electrocatalysts for alkaline electrolysis.     

A robust bifunctional electrocatalyst for rechargeable zinc-air batteries: NiFe nanoparticles encapsulated in nitrogen-doped carbon nanotubes

Developing high-efficiency, low-cost, and stable bifunctional oxygen electrocatalysts is essential for the commercialization of rechargeable metal-air batteries. Herein, three-dimensional self-assembled microspheres via in situ encapsulation of NiFe alloy nanoparticles (NPs) into N-doping carbon nanotubes (NiFe@NCNTs) have been achieved through pyrolyzing a mixture of nickel-iron alkoxide and melamine. The as-prepared electrocatalyst exhibits outstanding oxygen reduction reaction (ORR) performance with a half-wave potential of 0.79 V and oxygen evolution reaction (OER) activity with a low overpotential of 330 mV at 10 mA cm^?2. The eminent activity of NiFe@NCNTs is ascribed to high dispersion of active sites (zero-dimensional core-shell structure of NiFe@NC) and one-dimensional conductive network (NCNTs). Accordingly, the zinc-air battery assembled with NiFe@NCNTs as the air cathode exhibits a long cycling life of 200 h with a high energy efficiency of 65.6%. This work may shed new light on the design of advanced bifunctional electrocatalysts toward metal-air batteries.     

Encapsulated spinel CuXCo3-XO4 in carbon nanotubes as efficient and stable oxygen electrocatalysts

The development of efficient, stable and cost-effective electrocatalysts for oxygen reduction reactions (ORR) and oxygen evolution reactions (OER), have become one of the most important bottlenecks in pursuing emerging renewable energy storage and environment friendliness technologies. In this study, we have successfully developed encapsulated Cu_XCo_3-XO₄ spinel nanocrystals in carbon nanotubes as high-performance bifunctional oxygen electrocatalyst by one-step hydrothermal reaction. As compared with other Co-based materials, the resulting Cu_XCo_3-XO₄@C composite presents excellent catalytic performance and outstanding stability for both OER and ORR with ultralow overpotential (η = 0.358 V) at a current density of 10 mA/cm² and half-wave potential (E_1/2 = 0.82 V) in alkaline solution, respectively. The developed strategy to encapsulate spinel into carbon nanomaterials via a controllable pathway, may open new opportunities for the encapsulation structures of other catalysts.     

Nickel foam-supported Fe,Ni-Polyporphyrin microparticles: Efficient bifunctional catalysts for overall water splitting in alkaline media

Developing highly active, stable and sustainable electrocatalysts for overall water splitting is of great importance to generate renewable H₂ for fuel cells. Herein, we report the synthesis of electrocatalytically active, nickel foam-supported, spherical core-shell Fe-poly(tetraphenylporphyrin)/Ni-poly(tetraphenylporphyrin) microparticles (FeTPP@NiTPP/NF). We also show that FeTPP@NiTPP/NF exhibits efficient bifunctional electrocatalytic properties toward both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Electrochemical tests in KOH solution (1 M) reveal that FeTPP@NiTPP/NF electrocatalyzes the OER with 100 mA cm⁻² at an overpotential of 302 mV and the HER with 10 mA cm⁻² at an overpotential of 170 mV. Notably also, its catalytic performance for OER is better than that of RuO₂, the benchmark OER catalyst. Although its catalytic activity for HER is slightly lower than that of Pt/C (the benchmark HER electrocatalyst), it shows greater stability than the latter during the reaction. The material also exhibits electrocatalytic activity for overall water splitting reaction at a current density of 10 mA cm⁻² with a cell voltage of 1.58 V, along with a good recovery property. Additionally, the work demonstrates a new synthetic strategy to an efficient, noble metal-free-coordinated covalent organic framework (COF)-based, bifunctional electrocatalyst for water splitting.     

One-step synthesis of carbon-encapsulated nickel phosphide nanoparticles with efficient bifunctional catalysis on oxygen evolution and reduction

As a promising and cost-efficient alternative to noble metal catalysts, transition metal phosphides (TMPs) show highly catalytic performance toward oxygen reduction and evolution reactions (ORR and OER). Mesoporous carbon-coated nickel phosphide (NiP) nanoparticles were successfully synthesized by thermal decomposition at 500 °C under N₂/H₂ (95:5) atmosphere. The NiP/C hybrid exhibits excellent OER/ORR activity. It can generate an OER current density of 10 mA cm^?2 at the overpotential of 0.26 V with a low Tafel slope of 43 mV dec^?1, and produce a limited ORR current density of 5.10 mA cm^?2 at 1600 rpm with a half-wave potential of 0.82 V via a 4-electron pathway. In addition, the OER/ORR catalytic currents remain considerable stable without significant loss for more than 25 h polarization. This work will open up a new avenue to design a bifunctional catalyst with a superior OER/ORR activity and stability, and this cost-efficient strategy will pave the way for the industrial application of the renewable energy technologies.     

Multi-active site CoNi-MOFs as non-noble bifunctional electrocatalysts for highly efficient overall water splitting

The high-efficiency non-precious metal catalysts for oxygen evolution (OER) and hydrogen evolution (HER) are of great significance to the development of renewable energy technologies. Herein, a multiple active sites CoNi-MOFs-DBD electrocatalyst modified by low temperature plasma (DBD) was successfully synthesized by converting metal hydroxyfluoride on nickel foam into a well-arranged MOFs array using vapor deposition. The as-prepared CoNi-MOFs-DBD electrode showed better HER and OER catalytic activity, super hydrophilicity, and excellent stability. In an alkaline medium, the overpotential of HER is 203 mV at 10 mA cm^?2 and that of OER is 168 mV at 40 mA cm^?2. When CoNi-MOFs-DBD was used as a bifunctional electrocatalyst for overall water splitting in a two-electrode system, a current density of 10 mA cm^?2 can be achieved at a low voltage of 1.42 V, which shows great potential in electrocatalytic water splitting.