Bifunctional CuS/Cl-terminated greener MXene electrocatalyst for efficient hydrogen production by water splitting

Abstract

Metal sulfides and 2D materials are the propitious candidates for numerous electrochemical applications, due to their superior conductivity and ample active sites. Herein, CuS nanoparticles were fabricated on 2D greener HF-free Cl-terminated MXene (Ti₃C₂Cl₂) sheets by the hydrothermal process as a proficient electrocatalyst for the hydrogen evolution reaction (HER) and overall water splitting. CuS/Ti₃C₂Cl₂ showed an overpotential of 163 mV and a Tafel slope of 77 mV dec⁻¹ at 10 mA cm⁻² for the HER. In the case of the OER, CuS/Ti₃C₂Cl₂ exhibited an overpotential of 334 mV at 50 mA cm⁻² and a Tafel slope of 42 mV dec⁻¹. Moreover, the assembled CuS/Ti₃C₂Cl₂||CuS/Ti₃C₂Cl₂ electrolyzer delivered current density of 20 mA cm⁻² at 1.87 V for overall water splitting. The CuS/Ti₃C₂Cl₂ electrocatalyst showed excellent stability to retain 96% of its initial value for about 48 hours at 100 mA cm⁻² current density. The synthesis of CuS/Ti₃C₂Cl₂ enriches the applications of MXene/metal sulfides in efficient bifunctional electrocatalysis for alkaline water splitting.