Ultrafine Co2P anchored on porous CoWO4 nanofiber matrix for hydrogen evolution: Anion-induced compositional/morphological transformation and interfacial electron transfer

Even though transition metal phosphides (TMPs) have been regarded as very promising catalysts for hydrogen evolution reaction (HER), exploring highly reactive TMPs-based catalysts with reliable stability in alkaline media remains an enormous challenge. Herein, using wafer-like Co(CO 3 ) 0.5 (OH)·0.11H 2 O as template followed by anion-exchange and further phosphorization process, it is synthesized a three-dimensional (3D) hierarchical porous heterostructure with highly dispersed ultrafine metallic Co 2 P nanoparticles uniformly anchored on porous conductive CoWO 4 nanofiber matrix, which not only promotes the electron transfer, but also avoids the deterioration of phosphide. In addition, the electron densities re-distribution within the heterostructure also contributes to the improved catalytic activity. Furthermore, the doping of W into Co 2 P gives proper H adsorption free energy ΔG H . Impressively, the Co 2 P/CoWO 4 /Ni foam (NF) exhibits an overpotential of 81 mV at −10 mA cm −2 and a Tafel slop of 47 mV dec −1 along with supreme long-term durability at −40 mA cm −2 . The present work also demonstrates different dosages of Na 2 WO 4 in the anion-exchange step will lead to different phase compositions and morphologies, giving rise to different HER electrocatalytic performances of the phosphorized samples.