Boosting interfacial charge separation of Ba5Nb4O15/g-C3N4 photocatalysts by 2D/2D nanojunction towards efficient visible-light driven H-2 generation

To efficiently facilitate the charge transfer by constructing heterojunction photocatalysts is a promising strategy for improving solar-driven hydrogen generation. Herein, a novel 2D/2D nanojunction architecture of Ba5Nb4O15/g-C-3 N-4 photocatalysts with powerful interfacial charge transfer are rationally designed. Advanced electron microscopy analysis elucidates the layered hexagonal nanosheets were coupled on the surface of ultrathin g-C3N4 forming a 2D/2D nanojunction. More importantly, such characterizations and theoretical calculations together illustrate that a strong interfacial charge transfer existed between the g-C3N4 layer and Ba-O layer of the Ba5Nb4O15 nanosheets, which fostered the efficient transfer and provided more massive reactive centers for photocatalytic hydrogen evolution. The unique 2D/2D structure in Ba5Nb4O15/g-C-3 N-4 heterojunction leads to generate numerous charge transfer nanochannels, and which could accelerate the interfacial charge separation efficiency to a great extent. Ba5Nb4O15/g-C-3 N-4 (1:20) sample displayed a remarkable photocatalytic H-2 evolution rate (2.67 mmol h(-1) g(-1)) in oxalic acid solution, nearly 2.35 times higher than that of single g-C3N4 under visible light and exhibits an outstanding photostability even after four cycles. This work would provide a new insight for the design of 2D/2D heterojunction photocatalyst with efficient interfacial charge transfer and separation for solar-to-H-2 conversion.