The majority of visible-light photocatalysts show very low hydrogen evolution activity in the absence of noble metal co-catalysts due to their fast carrier recombination rate. Metallic interstitial nitrides have been recognized as excellent hydrogen evolution electrocatalysts and therefore are promising alternative co-catalysts for photocatalytic hydrogen production. Herein we report a low-cost, efficient, noble-metal-free visible-light-driven hydrogen evolution photocatalyst composed of Ni3N/g-C3N4 heterostructures. The as-prepared photocatalyst with a Ni3N loading content of 3 wt% shows a high hydrogen evolution rate of 169 μmol g-1 h-1, which is slightly higher than that of 3 wt% Pt modified g-C3N4 (152.0 μmol g-1 h-1). The Ni3N/g-C3N4 photocatalysts also exhibit remarkable photostability for four consecutive cycles of photocatalytic activity tests with a total reaction time of 12 hours. The excellent performance of the Ni3N/g-C3N4 photocatalyst is ascribed to the formation of an optimal number of Ni3N/g-C3N4 heterojunctions that improve photogenerated carrier separation and offer abundant photocatalytically active sites for surface reactions.

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The development of highly active electrocatalysts is essential to the commercialization of water splitting. Introducing ligand of foreign metals is a promising approach to optimize the electronic structure of electrocatalyst and regulate chemisorption behavior of intermediate species.Herein, Ru(OH) x Cl y cluster−modified CoNi alloy nanoparticles encapsulated in nitrogen-doped graphene (Ru-CoNi@NC-X) was prepared by a partial galvanic replacement method. The electrochemical results indicated that a moderated Ru(OH) x Cl y cluster was beneficial to improve the both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) properties of CoNi alloy nanoparticles (CoNi@NC).