Ultrafine and highly-dispersed bimetal Ni2P/Co2P encapsulated by hollow N-doped carbon nanospheres for efficient hydrogen evolution

Ultrafine Ni2P/Co2P nanoparticles encapsulated in hollow porous N-doped carbon nanospheres are synthesized through a facile two-step access. Firstly, metallic Ni and Co coated by hollow N-doped spheres as precursors are obtained through a high temperature calcination route of organic polymer and inorganic Ni and Co salts. Then bimetal Ni2P/Co2P supported on N-doped carbon nanospheres are acquired by a facile phosphorization process. It is worth to note that aniline-pyrrole polymer can prevent fast growth and severe aggregation of Ni2P/Co2P, which implies more exposed active sites. Moreover, the calcination of hollow polymer spheres lead to the formation of ultrathin NC shell on the surface of Ni2P/Co2P hybrids, which can tune electronic structures, improve the conductivity and protect active sites from corrosion in harsh conditions. When used as HER catalyst, it displays remarkable catalytic activity in both acidic and alkaline solutions, which needs an onset potential of only 164 mV and 168 mV, respectively. Therefore, this work may propose a new strategy to design unique inorganic-organic heterostructures to combine ultrafine metal phosphides with porous carbon for efficient HER. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.