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

摘要

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(CO3)(0.5)(OH)center dot 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 Co2P nanoparticles uniformly anchored on porous conductive CoWO4 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 Co2P gives proper H adsorption free energy Delta G(H). Impressively, the Co2P/CoWO4/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 Na2WO4 in the anion-exchange step will lead to different phase compositions and morphologies, giving rise to different HER electrocatalytic performances of the phosphorized samples. (C) 2019 Elsevier Ltd. All rights reserved.