Two-dimensional g-C3N4/Ca2Nb2TaO10 nanosheet composites for efficient visible light photocatalytic hydrogen evolution

- Novel g-C3N4/Ca2Nb2TaO10 nanosheet composite was simply prepared by exfoliation-reassembly method.
- The hybridization between the g-C3N4 and Ca2Nb2TaO10 nanosheets provides an intimate interfacial connection.
- The synergistic effect of g-C3N4 and Ca2Nb2TaO10 nanosheets is exemplified for improving photocatalytic H2 evolution under visible light irradiation.

Scalable g-C3N4 nanosheet powder catalyst was prepared by pyrolysis of dicyandiamide and ammonium chloride followed by ultra-sonication and freeze-drying. Nanosheet composite that combines the g-C3N4 nanosheets and Ca2Nb2TaO10 nanosheets with various ratios were developed and applied as photocatalysts for solar hydrogen generation. Systematic studies reveal that the g-C3N4/Ca2Nb2TaO10 nanosheet composite with a mass ratio of 80:20 shows the best performance in photocatalytic H2 evolution under visible light-irradiation, which is more than 2.8 times out-performing bare g-C3N4 bulk. The resulting nanosheets possess a high surface area of 96 m2/g, which provides abundance active sites for the photocatalytic activity. More importantly, the g-C3N4/Ca2Nb2TaO10 nanosheet composite shows efficient charge transfer kinetics at its interface, as evident by the photoluminescence measurement. The intimate interfacial connections and the synergistic effect between g-C3N4 nanosheets and Ca2Nb2TaO10 nanosheets with cascading electrons are efficient in suppressing charge recombination and improving photocatalytic H2 evolution performance.

A new type of visible light active composite containing exfoliated g-C3N4 nanosheets and Ca2Nb2TaO10 nanosheets was prepared. Systematic studies reveal that the g-C3N4/Ca2Nb2TaO10 nanosheet composite with a mass ratio of 80:20 exhibits the best performance in photocatalytic H2 evolution under visible light-irradiation, which is more than 2.8 times out-performing bare g-C3N4 bulk. The enhancement of photocatalytic H2 evolution of the g-C3N4/Ca2Nb2TaO10 composite is attributed to the intimate interfacial connection and synergistic effect between g-C3N4 nanosheets and Ca2Nb2TaO10 nanosheets with cascading electrons for efficient charge recombination suppression.152