Kinetics-favorable heterojunctional CNTs@CuCo-LDH/BPQD electrode with boosted charge storage capability for supercapacitor

Abstract

Component modulation and structure construction are the fundamental strategies in designing electrode materials for supercapacitors. Layered double hydroxide (LDH) is considered the promising electrode material, while with the drawback of low electron transmission efficiency and pulverization hinder. Herein, a novel kinetics-favorable heterojunctional self-supporting film electrode, composed of carbon nanotubes (CNTs), CuCo-LDH, and black phosphorus quantum dots (BPQD), is successfully prepared and directly utilized as electrodes in the supercapacitor. Highly conductive CNTs evenly and heavily entangled with CuCo-LDH hollow structures, resulting in robust mechanical property, enhanced electrical conductivity, and accelerated charge transfer during a redox reaction. Together with the surface decorated high-carrier-mobility BPQD, constructing heterojunction and acting as an electron donor to provide numerous active sites and facilitate energy storage behavior, a promoted pseudocapacitive performance was obtained and furtherly demonstrated by the density functional theory simulations based on the adsorption energies of OH–. The as-fabricated CNTs@CuCo-LDH/BPQD electrode presents a maximum capacitance of 1061.6 F g−1. The as-assembled hybrid supercapacitor device represents energy density up to 62.1 Wh kg−1 and remarkable cycling performance with 79.1% capacity retention after 10,000 cyclic tests. The prototype supercapacitor of this work shed light on the engineering of LDH-based materials for practical energy storage devices.