Noble metal-free NiCo2S4/CN sheet-on-sheet heterostructure for highly efficient visible-light-driven photocatalytic hydrogen evolution

The development of low-cost cocatalysts is desirable for photocatalytic H-2 generation. Here, we are the first to demonstrate the in situ hydrothermal growth of NiCo2S4 nanosheets on g-C3N4 surfaces to construct a "sheet-on-sheet" heterostructure. The as-prepared NiCo2S4/CN heterostructured nanohybrid exhibits remarkably enhanced rates of visible-light-driven photocatalytic H-2 evolution without using a noble metal cocatalyst, such as Pt. Notably, the optimum loading of NiCo2S4 nanosheets is 10 wt%, providing the best H-2 performance rate of 293.4 mu molh(-1)g(-1), which is approximately 7 times higher than that of the single-component bulk CN. This result suggested that the improved photocatalytic activity can be primarily ascribed to the efficient interfacial transfer of the photogenerated charge pairs from CN to the NiCo2S4 nanosheets. These nanosheets serve as temporary electron reservoirs, resulting in a reduced charge recombination rate on the CN surfaces and increasing the amount of photogenerated charge pairs in the NiCo2S4 nanosheets. Furthermore, the increased potential of reactive surface sites, together with the extended light absorption range after the introduction of NiCo2S4 nanosheets on the CN substrate, may also play a certain role in improving the photocatalytic performance. This study reveals a promising and efficient route for using CN-based photocatalysts incorporated with a ternary transition metal sulfide cocatalyst, which have been prepared by the nanoarchitecture engineering of noble metal-free heterostructured interfaces for use in renewable energy production. (c) 2020 Elsevier B.V. All rights reserved.