Thermally reduced rGO‐wrapped CoP/Co2P hybrid microflower as an electrocatalyst for hydrogen evolution reaction
Taek‐Seung Kim; Hee Jo Song; Mushtaq Ahmad Dar; Hyun‐Woo Shim; Dong‐Wan Kim
Index: 10.1111/jace.15581
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Abstract
Cobalt phosphides (CoPx) are potential candidates for use as high‐efficiency hydrogen evolution reaction electrocatalysts that can replace noble metals, such as Pt. Typically, CoPx can be synthesized by phosphidation with Co‐based precursors such as oxides or hydroxides. In this study, we propose a new strategy for synthesizing CoPx through the thermal reduction in cobalt phosphate (Co3(PO4)2). A reduced graphene oxide‐wrapped CoP/Co2P hybrid microflower was successfully synthesized by a facile coprecipitation method in a Co3(PO4)2 matrix, followed by a thermal reduction process. Co3(PO4)2 can be transformed to CoP/Co2P by treatment at 700°C for 1 hour, maintaining the original particle morphology with the assistance of reduced graphene oxide (rGO). In a 0.5 mol/L H2SO4 solution, the rGO‐CoP/Co2P microflower catalyzes the hydrogen evolution reaction with an overpotential of 156 mV at a current density of 10 mA cm−2, a Tafel slope of 53.8 mV dec−1, and good stability as observed through long‐term CV and chronoamperometry tests.