Copper-Incorporated heterostructures of amorphous NiSex/Crystalline NiSe2 as an efficient electrocatalyst for overall water splitting

Abstract

• Novel Cu-implanted heterostructure of amorphous NiSe x /crystalline NiSe 2 is prepared. • Catalyst needs overpotential of 156.9 mV for HER and 339 mV for OER at 10 mA cm −2. • The catalyst-based electrolyzer requires a low cell voltage of 1.62 V at 10 mA cm −2. • The catalyst-based electrolyzer shows a long-term stability of 21.5 h in 1.0 M KOH. In this research, we designed a novel heterostructure of porous amorphous-crystalline nickel selenide incorporated with copper (Cu-(a-NiSe x /c-NiSe 2 )) and shelled over one-dimensional TiO 2 nanorods (NRs) to simultaneously accelerate both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics in alkaline environment. The Cu-(a-NiSe x /c-NiSe 2 )/TiO 2 NRs supported by carbon cloth displayed as an effective bifunctional catalyst, which required low overpotentials of 156.9 mV for HER and 339 mV for OER to achieve a current response of 10 mA cm −2 in 1.0 M KOH medium. An electrolyzer derived from the Cu-(a-NiSe x /c-NiSe 2 )/TiO 2 NRs material allowed an operation voltage of 1.62 V at 10 mA cm −2 along with good long-term stability after 21.5 h operation towards water splitting in alkaline medium. This achievement was resulted from the fine-tuned 3D porous architecture of the amorphous NiSe x -crystalline NiSe 2 heterostructures doped by copper, which led to significant modulation of electronic properties as well as large surface of exposed electroactive site/types, thereby effectively promoting the catalytic performance. This study suggested a rational approach of structure and shape engineering to design a potential catalyst for producing green hydrogen via water spitting.