CoP nanosheet assembly grown on carbon cloth: A highly efficient electrocatalyst for hydrogen generation

Abstract

There exists a strong demand to replace expensive noble metal catalysts with cheap metal sulfides or phosphides for hydrogen evolution reaction (HER). Recently metal phosphides such as Ni<inf>x</inf>P, FeP and CoP have been considered as promising candidates to replace Pt cathodes. Here we report that the nanocrystalline CoP nanosheet assembly on carbon cloth can be formed by a two-step process: electrochemical deposition of Co species followed by gas phase phosphidation. The CoP catalyst in this report exhibits a Tafel slope of 30.1mV/dec in 0.5M H<inf>2</inf>SO<inf>4</inf> and 42.6mV/dec in 1M KOH. The high HER performance of our CoP catalysts is attributed to the rugae-like morphology which results in a high double-layer capacitance and high density of active sites, estimated as 7.77×10¹⁷sites/cm².