CeO2-embedded mesoporous CoS/MoS2 as highly efficient and robust oxygen evolution electrocatalyst

Transition metal sulfides (TMSs) are promising electrocatalysts for boosting oxygen evolution reaction (OER) but their poor stability hinders the practical applications. Herein, a mesoporous CoS/MoS2 polyhedron is synthesized for in situ embedded with CeO2 nanoparticles (denoted as CeO2@CoS/MoS2). Electrochemical experimental results indicate that dispersion of a proper amount of CeO2 (20 wt%) cocatalyst on the interface of CoS/MoS2 has activated abundant Co/Mo sites and induced oxygen vacancies/defects to boost the OER activity. 20%CeO2@CoS/MoS2 displays excellent OER electrocatalytic performance in alkaline with an overpotential of 247 mV to reach the current density of 10 mA cm−2 and a Tafel slope of 64 mV dec-1. More importantly, the embedded CeO2 particles have effectively prevented the binary metal sulfide from corrosion through Ce3+/Ce4+ switching, thus enhancing its stability and displaying a 12-hours continuous OER electrocatalysis at 10 mA cm−2. Our result represents one of rare examples by assembling cocatalyst within mesoporous hetero-structural binary sulfides to improve the electrocatalytic performance for OER.