Microwave-assisted synthesis of cobalt phosphide using ionic liquid as Co and P dual-source for hydrogen evolution reaction

Abstract Cobalt phosphide nanoparticles (Co 2 P) were synthesized via microwave radiation or pyrolysis at 400 °C, and two ionic liquids (IL) were applied as the phosphorus and cobalt dual-source for fabricating Co 2 P. In the microwave radiation method, tetrabutylphosphonium tetrachlorocobaltate(II) ([P 4,4,4,4 ] 2 [CoCl 4 ]) with carbon nanotubes (CNTs) was utilized to obtain the Co 2 P/CNTs-1 via one step phosphidation within 6 min. These as-prepared materials were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrocatalytic performance of microwave-prepared Co 2 P/CNTs-1 toward hydrogen evaluation reaction was investigated in acidic solution, which shows a good catalytic activity with onset overpotential of 80 mV, Tafel slope of 58 mV dec −1 , current densities of 10 and 20 mA cm −2 at overpotentials of 135 and 170 mV, respectively. This microwave-assisted strategy for synthesis of Co 2 P provides a remarkable advantage of preparation process in a quite short time, which also is a simple operation and energy efficient method.