Nitrogen-doped CoP as robust electrocatalyst for high-efficiency pH-universal hydrogen evolution reaction

Although significant achievements have been made in the development of efficient transition metal phosphide (TMP) based electrocatalysts for hydrogen evolution reaction (HER) under acidic and alkaline media, TMP-based electrocatalysts with remarkable HER performances under neutral media has been rarely reported. Herein, we report the synthesis of nitrogen doped CoP nanoflower grown on conductive carbon cloth (N-CoP/CC) that possesses excellent HER performance, with an overpotential of 74 mV to achieve the current density of 10 mA cm−2 in 1.0 M PBS (phosphate buffer solution, pH = 7), outperforming almost all the documented non-noble TMP-based electrocatalysts. In addition, the N-CoP/CC also displays Pt-like performance in 1.0 M KOH and 0.5 M H2SO4, with overpotentials of 39 and 25 mV to achieve the current density of 10 mA cm−2, respectively. Density functional theory (DFT) calculations and experimental results reveal that doping with N can efficiently affect the electronic states of Co d-orbital and optimize the free energy of hydrogen adsorption (ΔG*H) to the optimal value, resulting in enhanced HER performance.