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Heteroatom doping, especially with elements of lower electronegativity and smaller atomic radius, can effectively modulate the electronic structure and surface properties of electron materials, facilitating the electrochemical performance of supercapacitors. Herein, we have designed boron-doped NiCoP nanoarrays grown on carbon cloth (B-NCP-CC) for supercapacitor cathode materials using a simple process method combining hydrothermal, calcined phosphating and boronation processes. The introduction of boron, with lower electronegativity (2.04) and smaller atomic radius (0.85 Å) than phosphorus (2.19 and 1.00 Å), induces electron redistribution and shortens the Ni/Co–B bonds, enhancing their redox activity and charge transfer kinetics. The boron doping greatly enables the B-NiCoP-CC-18 (NiCoP-CC borated for 18 h) cathode material to provide a high capacity of 801 C g−1. The assembled B-NiCoP-CC-18‖‖AC hybrid supercapacitor achieves a high energy density of 73.22 W h kg−1 at a power density of 963.8 W kg−1 and retains 90% capacity after 5000 cycles, significantly improving the stability of nickel-based materials. Besides, density functional theory (DFT) calculations further elucidate that the introduction of boron increases the d-band centers of Ni and Co in NiCoP, promoting the conductivity and enhancing the electrochemical properties. [ABSTRACT FROM AUTHOR]

Electrocatalytic O2 conversion and water-splitting hold great promise to enable the chemicals–electricity inter-transition in many renewable-energy initiatives. Enhancing the kinetics of the oxygen reduction reaction (ORR) is challenging. Here, we present that Zn3(VO4)2/Ni(OH)2/rGO (reduced graphene oxide) nanosheet arrays-a Zn3(VO4)2/Ni(OH)2 composite in the form of nanometre-thick nanosheets on an rGO substrate-serve as an efficient and stable electrocatalyst for the ORR in alkaline electrolytes. The thin-sheet structure and smaller free energy of Zn3(VO4)2/Ni(OH)2, as well as the excellent conductivity of the rGO substrate, enable a large electrochemically-active surface area and a high electron transport, contributing to the superior electrocatalytic oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Furthermore, Zn3(VO4)2/Ni(OH)2/rGO and Zn3(VO4)2/Ni(OH)2 samples exhibit remarkable long-term water-splitting stability of 48 h. Density functional theory (DFT) calculations reveal the optimized intermediate affinity ability at the Ni(OH)2 side, due to electrons transferring from Ni(OH)2 to Zn3(VO4)2. Additionally, the higher hybridization degree of density of states (DOS) boosts electron transfer in the electrocatalytic process. More broadly, this work provides new inspiration for the construction of a novel noble metal-free electrocatalyst that could show great promise in energy electrocatalysis. [ABSTRACT FROM AUTHOR]

Electrode materials exhibiting higher structural stability and electrochemical activity remain a priority in improving the electrochemical performance of supercapacitors (SCs). Herein, we report the design and synthesis of a novel nanoplate-on-nanosheet architecture with vertically aligned ZnCo2O4 (ZCO) porous nanoplates anchored on ultrathin delaminated-Ti3C2 (d-TC) nanosheets as a high-performance electrode for electrochemical SCs. The unique robust nanoplate-on-nanosheet adhesion promises fast electron and ion transport, large electroactive surface area, and excellent structural stability. Importantly, benefiting from the features of such a configuration, the ZCO/d-TC-350 composite electrode displays a high specific capacity of 195.8 C g−1 at a current density of 1 A g−1. Moreover, the constructed hybrid supercapacitor (HSC) consisting of ZCO/d-TC-350‖‖active carbon (AC) achieves a high energy density of 15.6 W h kg−1 at a power density of 551.1 W kg−1 and superior long-term stability with 89.5% capacitance retention after 4000 cycles. This work provides a promising strategy for the preparation of advanced MXene-based electrodes for electrochemical capacitors. [ABSTRACT FROM AUTHOR]