Metal and phosphonium-based ionic liquid: A new Co and P dual-source for synthesis of cobalt phosphide toward hydrogen evolution reaction

摘要

Phosphonium-based ionic liquid, containing cobalt ion, was applied as novel phosphorus and metal dual-source for fabrication of cobalt phosphide. Trihexyl(tetradecyl)phosphonium tetrachlorocobaltate(II) ([P-6,P-6,P-6,P-14](2)[CoCl4]) with carbon nanotubes (CNTs) was utilized to obtain the Co2P/CNTs via one step phosphidation. This material exhibits a good catalytic activity toward hydrogen evolution reaction (HER) including an onset overpotential of 85 mV, a Tafel slope of 47 mV dec(-1), current densities of 10 and 20 mA cm(-2) at overpotentials of 150 and 178 mV, and it has a good stability to keep the HER activity. All experimental results confirmed that [P-6,P-6,P-6,P-44](2)[CoCl4] can form Co2P without adding other reagent and CNTs can improve the electrical conductivity and contribute to the formation of cobalt phosphide. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.