Influence of Phosphidation on CoSe2 Catalyst for Hydrogen Evolution Reaction

Abstract The development of highly active and earth‐abundant electrocatalyst for the hydrogen evolution reaction (HER) is essential for hydrogen based energy technologies. Recently, cobalt chalcogenides and phosphides have been extensively investigated as a promising class of non‐precious electrocatalyst for HER because of its high catalytic activity. Here, we have grown a novel and efficient cobalt selenide|cobalt phosphide (CoSe 2 |CoP) based HER catalyst on carbon fiber paper (CFP) through a facile conversion of CoSe 2 nanostructures into a hybrid CoSe 2 |CoP by phosphidation. Phosphorus compositions in the CoSe 2 |CoP nanosheets are controllable by adjusting the time duration of phosphidation viz., 15, 30 and 60 min. The catalyst CoSe 2 |CoP/CFP in acidic media at 30 min showed higher catalytic activity with low overpotential (η) of 140 mV at 10 mA/cm 2 and a Tafel slope of 42 mV/dec than parent CoSe 2 /CFP (η ‐ 219 mV at 10 mA/cm 2 ; Tafel slope ‐ 44 mV/dec) and CoP/CFP (η ‐ 168 mV at 10 mA/cm 2 ; Tafel slope ‐ 86 mV/dec). The improved HER activity of CoSe 2 |CoP is attributed to the formation of the hybrid nanosheets and the synergistic effect between CoP and CoSe 2 . Moreover, the surface morphology of CoSe 2 |CoP at 30 min catalyst plays a significant role in electron transportation. Thus, the present work opens a new potential way to design and develop novel hybrid HER electrocatalysts based on CoSe 2 |CoP as an efficient energy conversion system through their composition and structural morphology.