Constructing heterojunctions of CoAl2O4 and Ni3S2 anchored on carbon cloth to acquire multiple active sites for efficient overall water splitting

Abstract

Constructing heterojunction interface is an efficient strategy to accelerate the catalytic activity for electrochemical reaction. In this work, a novel composite heterojunction electrocatalyst (CAO/NiS400/CC), deriving from the combination of CoAl2O4 (CAO) and Ni3S2 anchored on carbon cloth (CC) was prepared, through hydrothermal process followed by electrodeposition. After successful synthesis, CoAl2O4 particles were intricately embedded in Ni3S2 and formed an active heterostructure, exhibited outstanding catalytic capacity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) and improved the efficiencies of overall water splitting. As expected, the composite heterojunction electrocatalyst demonstrated excellent catalytic performances with lower overpotential of 163.2 mV at 100 mA·cm−2 and Tafel slope of 20.4 mV·dec-1for HER and 400 mV at 100 mA·cm−2 and Tafel slope of 51.1 mV·dec-1 for OER, respectively, accompanied by long-term structural stability after 40 h and 3000 Cyclic Voltammetry (CV) cycles. Moreover, Density functional theory (DFT) calculation illustrated that the robust electrocatalytic performance was attributed to the simultaneous presence of multiple catalytic active sites surrounding the heterojunction interface. Furthermore, CAO/NiS400/CC electrocatalyst facilitated the overall water splitting reaction under a cell voltage of only 1.48 V with dual catalytic capabilities for HER and OER. The combined action of active catalytic sites within both CAO and Ni3S2 around the interface contributed the optimal electrocatalytic performance, making the CAO/NiS400/CC as a promising alternative to electrocatalysts for water splitting.