The challenge to develop a highly efficient and affordable electrocatalyst for the oxygen evolution reaction (OER) could be fulfilled by a newly developed transition metal boron amorphous alloy electrocatalyst. This could successfully improve the overall efficiency of the electrochemical water splitting. Herein, we demonstrate the development of an entirely new Cu−Co−B amorphous alloy nanosheet (NS), which can act as an industrially promising electrocatalyst for the OER. Among a series of studied compositions, surface activated CuCo 2 B NSs with 5−6 nm thickness offer highly promising OER performances with an exceptionally high current density of 1000 mA cm −2 at 270 mV of overpotential (η) in a 1.0 M KOH electrolyte. It can also afford η 100 = 204 mV and η 500 = 256 mV, which remains intact for 60 h, with the lowest Tafel slope and charge transfer resistance and the highest electrochemically active sites with a promising turnover frequency and 87% Faradaic efficiency. It also fulfills the commercial requirement criteria of the OER process in 30 wt % KOH. Extensive experimental analyses led to a Cu−Co synergistic-based mechanism by the in situ formed active sites for the adsorption of *OH and *OOH reaction species, reconstruction of the catalyst surface by forming a metal hydroxides/oxyhydroxides precatalyst, modulation of electronic structure due to the rich defect nature, and topological disorder of the amorphous catalyst. Density functional theory (DFT) studies reveal that CuCo 2 B NSs are the most promising candidates for OER due to the lowest barrier for OER and thus the lowest adsorption energies, and the Cu-centers effectively and synergistically enhance the OER.

Metastable amorphous alloys having 2‐dimensional morphology are expected to be an excellent electrode materials for supercapacitors because of their defect rich nature, high degree of compositional as well as topological disorder and internal stresses. Herein, we investigated and demonstrated a new series of Cu−Co−B amorphous alloy nanosheets for energy storage. A clear and significant energy storage improvement by this Cu−Co−B nanosheets over the state‐of‐the‐art materials and flexible devices are manifested. Among the as‐synthesized materials, CuCo2B nanosheets exhibits an excellent specific capacity of 3503.6 F g−1 (389.2 mAh g−1) and a 99 % (at 50 A g−1) retention rate after 3000 cycles. An all‐solid state flexible symmetric Cu−Co−B|[EMIM][BF4] supercapacitor device (0–180° bending, 2.5 V) demonstrates a high energy density of 90.2 Wh kg−1, specific capacity (289.2 mAh g−1), power density (4623.6 W kg−1) and prolonged cycling stability (89 %) and Coulombic efficiency (104 %) over 10000 charge‐discharge cycles.

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Electrochemical supercapacitors (SCs) are high-efficiency electrochemical energy storage devices that can deliver energy at a very fast rate. Metal− organic framework (MOF)-derived layered double hydroxides (LDHs) are promising materials with great potential for commercial SC applications. In this study, a two-step synthetic strategy was developed to produce porous nanostructured ZnCoNi-LDH nanosheets (NSs) from bimetallic MOFs through a chemical reduction method. All the as-synthesized materials were characterized for their crystal structure, phase, morphology, and surface construction. The optimized ZnCo 2 Ni-LDH composition exhibited the best charge storage ability and specific capacitance among the different assynthesized compositions. The specific capacitance of the fabricated device ZnCo 2 Ni-LDH||cellulose paper-KOH||ZnCo 2 Ni-LDH was found to be 348.2 F g −1 at 1.0 A g −1 , with a maximum energy density of 54.4 W h kg −1 and a power density of 4439.0 W kg −1 . After 10,000 continuous charge−discharge cycles, the device retained 86% of its capacitance. It also delivered a high-capacitance-specific Coulombic efficiency (57−60%). A mechanistic study corroborated the experimental results that the high pore volume, possible insertion of a greater number of electrolyte ions, multioxidation states of Ni and Co ions, and their synergistic effect with Zn 2+ all contributed to the diffusion-controlled charge storage behavior. The charge storage characteristics of the device were found to be a combination of redox and electrostatic effects, forming a facile hybrid SC.