One-step synthesis of CoPSe–CoSe2/CNTs as efficient electrocatalyst for oxygen evolution reaction

Abstract By employing a facile one-step phosphorization and selenization method, we successfully synthesized a unique Co–P–Se ternary system which combines the Se doping in the CoP crystal structure and the mixing with amorphous cobalt selenide (CoPSe–CoSe2/CNTs). The formation mechanism is studied by SEM, XRD, TEM, and Raman techniques. The catalytic activity of the newly obtained CoPSe–CoSe2/CNTs material is then investigated by adopting the material as catalyst for oxygen evolution reaction (OER). We found that the OER performance of the as-prepared CoPSe–CoSe2/CNTs catalyst shows strongly dependency on the amount of amorphous CoSe2 and a volcano-like relationship is observed which the OER catalytic activity increases firstly to reach its maximum and then slightly drops down by further increasing the amount of amorphous CoSe2 in the catalyst system. The CoPSe–CoSe2/CNTs electrode with optimized amount of CoSe2 can drive a current density of 10 mA cm−2 with only 268 mV, far lower than the value required on the CoP/CNTs (305 mV) and CoSe2/CNTs (324 mV) electrodes.