Al-doping-induced electronic structure modulation of CoSe2 for efficient hydrogen evolution reaction

The development of highly efficient, long-lasting, and earth-rich electrocatalysts for hydrogen evolution processes (HER) is crucial to the advancement of hydrogen energy. Due to its improved catalytic activity, extraordinary chemical stability, and low cost, pyrite cobalt selenide (CoSe2) has become an incredibly potential replacement for Pt-based HER electrocatalysts. However, because of limited hydrogen adsorption and accompanying restrictions in its electronic structure, its practical application has run into difficulties. Herein, we have introduced aluminum (Al) into CoSe2/CC nanowire arrays on carbon cloth using a simple hydrothermal and selenization method. The synthesized materials serve as highly effective catalysts for HER, with the optimized AlCoSe2/CC demonstrating a significantly overpotential reduced by nearly 90 mV compared to pure CoSe2/CC (from 243 mV to 153 mV) at a current density at 10 mA cm-2 and a small Tafel slope of 88 mV dec-1. Moreover, these catalysts exhibit exceptional durability, sustaining their performance for 24 h. Based on the experimental results and subsequent density functional theory (DFT) calculations, it has been demonstrated that Al doping can significantly enhance the electronic conductivity, maximize the hydrogen evolution adsorption energy, and improve the charge transfer ability. This work offers a profound insight into the correlation between cation substitution in non-precious metal-based catalysts and the enhancement of intrinsic HER catalytic performance.