Ni-Co layered double hydroxides cocatalyst for sustainable oxygen photosynthesis

[Display omitted] •Binary Ni-Co LDHs/carbon nitride layered junctions are developed.•The geometric similarity and electrical coupling of Ni–Co LDHs with CNU facilitate the formation adaptive layered junctions.•The enhanced photocatalytic activity and selectivity toward water oxidation is achieved for the Ni-Co LDHs/carbon nitride hybrids.•An effective interfacial 2D junction between water oxidation catalysts and semiconductors is beneficial for artificial photosynthesis. The oxidation side of overall water splitting reaction, involving multiple electron transfer, OH bond cleavage, and OO bond formation, is a vital step to control the overall activities of water spitting. However, this process is usually restricted by the huge energy barrier and sluggish reaction kinetics. Recently, cobalt-based nanomaterials have been proved to be capable of decreasing the activation energy and accelerating the reaction kinetics. In principle, many factors will largely affect the activities, such as the loading contents, the size and structure of the cocatalysts. In order to achieve an overall enhancement of catalytic activities, it is reasonable to fabricate a tight and well matching junction that could efficiently promote the interface charge migration and separation. Herein, a high-performance water oxidation junction with layered structure was fabricated via in-situ growth of Ni-Co layered double hydroxides (LDHs) on graphitic carbon nitride nanosheets. Owing to the similarity of their layered stacking geometry, LDHs will strongly anchor on the surface of carbon nitride nanosheets, which could favor the photocatalytic water oxidation activities. As expected, the optimized binary catalysts showed remarkably enhanced activity for the photocatalytic water oxidation to release oxygen, which was 6.5 times higher than that of pure carbon nitride materials without loading the cocatalyst.