Hydrogen Deficient Nickel‐Cobalt Double Hydroxide for Photocatalytic Overall Water Splitting

Developing highly efficient and low cost photocatalyst for overall water splitting has long been a pursuit for conversing solar power to clean hydrogen energy. Herein, we demonstrate that nonstoichiometric nickel-cobalt double hydroxide could implement overall water splitting by itself upon sunlight irradiation, avoiding the consumption of noble-metal co-catalyst. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so-called L-NiCo nanosheets with nonstoichiometric composition and O 2- /Co 3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O 2- and Co 3+ ions boost hydrogen and oxygen evolution reactions, respectively. As such, the photocatalyst achieves a H 2 evolution rate of 1.7 mumol h -1 under the AM 1.5G sunlight irradiation and apparent quantum yield (AQE) of 1.38% at 380 nm.