Multifunctional Co–B–O@CoxB catalysts for efficient hydrogen generation

The development of efficient and non-noble catalyst is of great significance to hydrogen generation techniques. Three surface-oxidized cobalt borides of Co–B–O@Co x B (x = 0.5, 1 and 2) have been synthesized that can functionalize as active catalysts in both alkaline water electrolysis and the hydrolysis of sodium borohydride (NaBH 4 ) solution. It is discovered that oxidation layer and low boron content favor the oxygen evolution reaction (OER) activity of Co–B–O@Co x B in alkaline water electrolysis. And surface-oxidized cobalt boride with low boron content is more active toward hydrolysis of NaBH 4 solution. An alkaline electrolyzer fabricated using the optimized electrodes of Co–B–O@CoB 2 /Ni as cathode and Co–B–O@Co 2 B/Ni as anode can deliver current density of 10 mA cm −2  at 1.54 V for overall water splitting with satisfactory stability. Meanwhile, Co–B–O@Co 2 B affords the highest hydrogen generation rate of 3.85 L min −1 g −1 for hydrolysis of NaBH 4 at 25 °C.