Magnetic metal phosphide nanorods as effective hydrogen-evolution electrocatalysts

Efficient and economical hydrogen evolution reaction (HER) from water splitting holds a bright prospect for clean energy. Replacement of expensive Pt-based catalysts with earth-abundant catalysts is beneficial for this field. In this study, nanoscale magnetic metal phosphides including Co2P, Co1.33Ni0.67P and Ni2P nanorods are synthesized by a facile solution method. Their HER activities and stabilities on glassy carbon and Ti electrodes are investigated. The Co2P nanorods deposited on glassy carbon electrodes are found to show higher activity and better reversibility than the Co1.33Ni0.67P and Ni2P counterparts. Nevertheless, the Co1.33Ni0.67P and Ni2P samples on Ti electrodes gain a significant activity promotion after annealing in H2/Ar atmosphere. Investigation of the Tafel curves shows that the Co2P nanorods on glassy carbon have the lowest Tafel slope while their exchange current density on Ti electrode exhibits a high value which is comparable to that of Pt electrode. Furthermore, the cyclic voltammetric tests show that the reversibility of annealed Co2P on Ti electrode is the best, which emphasizes the superiority of Co species in catalyzing HER reaction. Finally, the three magnetic metal phosphide catalysts are found to exhibit good stabilities in acidic conditions according to the galvanostatic testing results.