Construction of Co–Ni–B heteronanosheets electrocatalyst for enhanced oxygen and hydrogen evolution

The electrocatalytic activity of metal boride-based materials is influenced by electron transfer between the metal and boron. Herein, we report a strategy to regulate the electronic structure of the active site and surface reconstruction by constructing Co–Ni–B heteronanosheets on reduced graphene oxide (Co–Ni–B/RGO). For Co–Ni–B/RGO heterostructures, the reverse electron transfer of boron leads to electron enrichment around the metal site, showing a positive effect for hydrogen evolution reaction (HER). In addition, the energy barrier of surface reconstruction to form active (oxy)hydroxide species decreases, and the electronic structure of the (oxy)hydroxide is modified by metaborate, resulting in enhanced oxygen evolution reaction (OER) activity. The Co–Ni–B/RGO exhibits high activity towards HER and OER, and delivers a quite low cell voltage of 1.580 V at 10 mA cm−2 and stability of over 20 h for overall water splitting. This work provides a scalable strategy for modulating catalyst surface properties by constructing heterostructures.