Highly active sites of NiVB nanoparticles dispersed onto graphene nanosheets towards efficient and pH-universal overall water splitting

Production of hydrogen (H-2) and oxygen (O-2) through electrocatalytic water splitting is one of the sustainable, green and pivotal ways to accomplish the ever-increasing demands for renewable energy sources, but remains a big challenge because of the uphill reaction during overall water splitting. Herein, we develop high-performance non-noble metal electrocatalysts for pH-universal water splitting, based on nickel/vanadium boride (NiVB) nanoparticles/reduced graphene oxide (rGO) hybrid (NiVB/rGO) through a facile chemical reduction approach under ambient condition. By virtue of more exposure to surface active sites, superior electron transfer capability and strong electronic coupling, the as-prepared NiVB/rGO heterostructure needs pretty low overpotentials of 267 and 151 mV to deliver a current density of 10 mA cm(-2) for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) respectively, with the corresponding Tafel slope of 44 and 88 mV dec(-1) in 1.0 M KOH. Moreover, the NiVB/rGO electrocatalysts display a promising performance in a wide-pH conditions that require low overpotential of 310, 353 and 489 mV to drive a current density of 10 mA cm(-2) for OER under 0.5 M KOH, 0.05 M H2SO4 and 1.0 M phosphate buffer solution (PBS) respectively, confirming the excellent electrocatalytic performance among state-of-the-art Ni-based electrocatalysts for overall water splitting. Therefore, the interfacial tuning based on incorporation of active heterostructure may pave a new route to develop bifunctional, cost-effective and efficient electrocatalyst systems for water splitting and H-2 production. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.