Facile synthesis of CoX (X = S, P) as an efficient electrocatalyst for hydrogen evolution reaction

Abstract

Developing environmentally-friendly and earth-abundant electrocatalysts is desirable for an efficient hydrogen evolution reaction (HER). Herein, we report a facile and controllable synthesis of CoX (X = S, P) nanocatalysts by the chemical conversion of thin Co(OH)₂ nanoplates under mild conditions. Both catalysts delivered high catalytic activity for HER. Small onset potentials of 59 and 32 mV, along with low Tafel slopes of 56.2 and 54.8 mV dec⁻¹, were observed for CoS and CoP, respectively. Analyses suggest that the better HER performance of CoP nanocatalysts could be attributed to the intrinsically more positively charged nature of the Co metal center, the longer Co–P bond length, and more catalytic active sites due to the smaller size of the CoP nanocatalysts. High catalytic stability in acidic media was also observed for both CoS and CoP catalysts for a duration of 18 hours.