The effect of ammonium citrate on CoP/CC morphology and its electrocatalytic hydrogen evolution performance

The development and improvement of new transition metal-based catalysts to replace Pt/C electrodes in electrolytic water hydrogen evolution has attracted much attention. In this work, we used ammonium citrate as additive, mixed with cobalt nitrate, through hydrothermal and phosphating methods to get supported on carbon cloth catalyst with new morphology (referred to as E380-CoP/CC, E380 stands for ammonium citrate). Benefit from the dense and fine nanosheet structure, compared with cobalt phosphating alone, the catalyst E380-CoP/CC has a significant improvement in hydrogen evolution performance. In 1 M KOH, the overpotential is 57 mV at the current density of 10 mA cm−2, and the Tafel slope is only 40 mV dec-1, which is very close to the hydrogen evolution performance of Pt/C electrode. In addition, the catalyst has favorable stability and superior hydrogen evolution performance after undergoing CV 2000 cycles and 48 h i-t test. This work offers a reliable idea for realizing electrolytic water hydrogen evolution technology with high efficiency and energy saving.