Surface-induced Co/Co9S8 nanodots embedded in nitrogen-doped hollow carbon nanocubes for high-performance overall water splitting

Abstract

To obtain highly efficient water splitting, it is crucial to develop electrocatalysts with suitable structures, morphologies, and electronic states. we have developed a novel synthesis method that utilizes a sophisticated MOF-engaged approach to fabricate multi-dimensional Co/Co9S8 nano-heterojunctions (Co/Co9S8-NHs) that penetrate the hollow nanocubes, the as-prepared sample is referred to Co/Co9S8@HCNCs. Specifically, Co nanoparticles are encased and strung by single-phased Co9S8, generating Co/Co9S8 core/shell heterojunctions with an average size of 8 nm in the mesoporous walls of the carbon nanocubes. The as-prepared electrocatalyst shows exceptional stability and activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), contributing to the abundant active sites and fast mass transfer. Therefore, the uniquely designed heterostructure enables the remarkable OER and HER activities, delivering a current density of 10 mA cm−2 at the ultralow overpotential of 190 mV and 140 mV, separately. Furthermore, the Co/Co9S8@HCNCs can be scaled up and utilized as electrodes in industrial electrolyzers for water splitting. The device shows a consistent cell voltage of 1.52 V at the current density of 10 mA/cm2 over 30 h. This research demonstrates a facile and straightforward approach to developing complex catalytic interfaces on a nanoscale level, leading to increased catalytic activity through the exploitation of nano-heterojunction structures.