Sn doped cobalt-based phosphide as bifunctional catalyst for ethanol oxidation reaction and hydrogen evolution reaction

The development of non-precious metal bifunctional electrocatalysts is of practical significance to solve resource shortage and energy crisis. In this study, to accelerate mass/electron transfer and maximize the area of exposed active sites, a coral-like Sn-Co-P/NF bi-functional electrocatalyst was synthesized by electrodeposition for total hydrolysis. Ethanol oxidation reaction (EOR) was used to replace oxygen evolution reaction (OER) with hydrogen evolution reaction (HER) to further improve the water electrolysis rate. The catalyst showed great electrochemical activity and stability in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions. At a current density of 10 mA cm- 2, the required overpotential for HER is only 59 mV (vs. RHE) and 304 mV (vs. RHE) for OER, and the corresponding Tafel slopes are 42 mV & sdot;dec- 1 and 67 mV & sdot;dec- 1, respectively. When EOR was substituted for anodic oxygen evolution, the overpotential could be reduced by 240 mV. In addition, when Sn-Co-P/NF is used as a water-ethanol electrolytic cell assembled with anode and cathode, the current density of 10 mA cm-2 can be reached with only 1.49 V operating voltage, which is 130 mV lower than that of hydrolysis alone, and it also shows good durability in the test of 28 h. Therefore, the experimental results show that it is feasible to use EOR instead of OER to coupling with HER, the catalyst has broad application prospects in industrial electrolysis.