In-situ fabrication of vertical heterogeneous nickel diselenide-molybdenum diselenide architectures as bifunctional overall water-splitting electrocatalyst

Despite the rapid advances in electrocatalysts based on two-dimensional (2D) transition metal dichalcogenides (TMDs) materials, they are subject to serious aggregation, poor conductivity and the presence of inactive basal planes. Herein, we have successfully demonstrated the in-situ construction of NiSe₂–MoSe₂ heterostructure arrays on carbon cloth (NiSe₂–MoSe₂/CC) by a facile two-step hydrothermal process. The presence of the synergistic effect in the heterostructures effectively optimizes the poor conductivity and hydrophilicity, and thus enables fast electron transfer, leading to enhanced electrochemical reaction. Furthermore, density functional theory calculations reveal that the electrons redistribution at the heterojunction interface and the reduced Gibbs free energy of hydrogen adsorption for hydrogen evolution reaction (HER)/the Gibbs free energy change value of rate-determining step for oxygen evolution reaction (OER), thus enhancing the HER/OER catalytic activity. Importantly, the device displays a good performance with a low overpotential of 98 and 310 mV for HER and OER, respectively, and a low cell voltage of 1.59 V for its corresponding electrolyzer (10 mA cm⁻²). This work presents the high-performance water splitting of bifunctional electrocatalysts based on 2D TMDs materials and offers a novel design concept of interface engineering.