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

Abstract

• Rare example of CeO 2 cocatalyst in situ loading in mesoporous sulfide. • The proper amount of CeO 2 (20 wt%) cocatalyst boosts OER activity. • CeO 2 prevented the binary sulfide from corrosion, enhancing its stability. • One of the best OER electrocatalysts reported so far. 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/MoS 2 polyhedron is synthesized for in situ embedded with CeO 2 nanoparticles (denoted as CeO 2 @CoS/MoS 2 ). Electrochemical experimental results indicate that dispersion of a proper amount of CeO 2 (20 wt%) cocatalyst on the interface of CoS/MoS 2 has activated abundant Co/Mo sites and induced oxygen vacancies/defects to boost the OER activity. 20%CeO 2 @CoS/MoS 2 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 CeO 2 particles have effectively prevented the binary metal sulfide from corrosion through Ce 3+ /Ce 4+ 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.