Oxygen vacancies engineered self-supported B doped Co3O4 nanowires as an efficient multifunctional catalyst for electrochemical water splitting and hydrolysis of sodium borohydride

Developing earth abundant electrocatalyst is imperative to large-scale hydrogen production for transforming current fossil fuel-based economy into future renewable energy economy. In this paper, we report the synthesis of self-supported V O B-Co 3 O 4 /NF nanowire arrays directly grown on Ni foam, which can serve as a trifunctional catalyst for producing hydrogen and oxygen by electrolyzing water in alkaline media or producing hydrogen via hydrolyzing alkaline NaBH 4 solution. The engineered boron and oxygen defects in Co 3 O 4 nanowires prove to effectively modulate their electronic structure leading to the increased electrical conductivity and create a large quantity of electroactive sites. The resulting self-supported V O B-Co 3 O 4 /NF electrode delivers a current density of 50 mA cm −2 at overpotentials of 184 mV for hydrogen evolution reaction (HER) and 315 mV for oxygen evolution reaction (OER) in 1.0 M KOH with excellent stability and durability. The V O B-Co 3 O 4 /NF as both cathode and anode requires 1.67 V to achieve a current density of 10 mA cm −2 for overall water splitting reaction. Besides, V O B-Co 3 O 4 /NF presents much higher hydrogen generation rate (HGR) of 7055 mL min −1 g catalyst −1 with activation energy (E a ) of ca. 29.7 kJ mol −1 . for hydrolytic dehydrogenation of alkaline NaBH 4 solution, outperforming most of the reported non-noble metal-based catalysts and even precious metal catalysts.