Multifunctional photo‐electrocatalysts of copper sulfides prepared via pulsed laser ablation in liquid: Phase formation kinetics and photo‐electrocatalytic activity

Designing a highly efficient and less expensive electrocatalyst for electrolyzers and fuel cells is of great importance to creating a sustainable future energy source. Herein, we applied a unique and extremely facile pulsed laser ablation in the liquid synthesis route for the fabrication of phase-engineered CuxSy nanospheres. The multifunctionality of these catalysts was assessed by examining the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and methanol oxidation reaction (MOR). As a result, low overpotentials of 390 mV (HER) and 440 mV (OER) were achieved for sulfur-rich and copper-rich samples in alkaline media, respectively. Furthermore, the high selectivity of Cu over methanol and the high number of electrochemically accessible active sites equal to 7.9 × 1016 promoted the MOR with a current density of 28.3 mA/cm2 at the vertex potential. It is worth emphasizing that in this research, we consider the electrocatalyst's initial electrocatalytic water decomposition function to gain a better understanding of the photoelectrocatalytic behavior. Using a beneficial photo-assisted electrochemical method, a high OER catalytic activity was obtained under light irradiation due to the large light absorption coefficients of the synthesized electrocatalysts, which facilitated electron transfer at the electrode-electrolyte interface.