The synergetic effect of h-BN shells and subsurface B in CoBx@h-BN nanocatalysts for enhanced oxygen evolution reactions

Abstract

Boron-containing cobalt (Co–B) nanoparticles (NPs) synthesized by the borohydride reduction process were subjected to ammonization. Part of B species segregate onto particle surfaces to form ultrathin h-BN shells which stabilize highly dispersed Co NPs under harsh conditions and the remaining B atoms interact strongly with Co atoms inside the NPs. The formed CoB_x@h-BN core–shell nanocatalysts exhibit an overpotential of 290 mV at a current density of 10 mA cm⁻² making them among the most active catalysts for the oxygen evolution reaction (OER) and they present 150 h OER stability. The improved OER performance has been attributed to the synergetic role of the confinement effect of h-BN shells and activation effect of subsurface B atoms. This work suggests a simple synthetic route to prepare highly active and stable metal nanocatalysts without using any surfactants and supports.