Hierarchical particle-on-sheet CoP fabricated by direct phosphorization of Co(OH)2/ZIF-67 hybrid for boosting hydrogen evolution electrocatalysis

Abstract Engineering an advanced noble-metal-free electrocatalyst for boosting hydrogen evolution reaction (HER) is highly desired, but remains a challenging task. In this work, hierarchical porous particle-on-sheet CoP was synthesized through direct gas-solid phosphorization of bi-compositional Co(OH)2/ZIF-67 precursor. This special morphology endows the hybrid CoP(C/Z) catalysts with more exposed active sites and favorable charge and ion transport pathways. Furthermore, the collective CoP units derived from two kinds of precursors would regulate the electronic structure and enhance the intrinsic activity of active site. As a consequence, the composition-optimized CoP(C/Z)-0.6 electrocatalyst could deliver superior activity towards HER with low overpotentials of 154 mV and 181 mV to achieve 10 mA cm-2 and 20 mA cm-2 current densities, a maximum TOF value of 0.0477 s-1, a Tafel slope of 85.1 mV dec-1, as well as good stability in alkaline electrolyte. This present study may shed light on the exploration of transition-metal phosphides with compositional and structural complexity for enhancing the electrocatalytic ability.