Insights into the efficient charge separation over Nb 2 O 5 /2D-C 3 N 4 heterostructure for exceptional visible-light driven H 2 evolution

Two-dimensional carbon nitride (2D-C 3 N 4 ) nanosheets are promising materials in photocatalytic water splitting, but still suffer from easy agglomeration and fast photogenerated electron–hole pairs recombination. To tackle this issue, herein, a hierarchical Nb 2 O 5 /2D-C 3 N 4 heterostructure is precisely constructed and the built-in electric field between Nb 2 O 5 and 2D-C 3 N 4 can provide the driving force to separate/transfer the charge carriers efficiently. Moreover, the strongly Lewis acidic Nb 2 O 5 can adsorb TEOA molecules on its surface at locally high concentrations to facilitate the oxidation reaction kinetics under irradiation, resulting in efficient photogenerated electrons-holes separation and exceptional photocatalytic hydrogen evolution. As expected, the champion Nb 2 O 5 /2D-C 3 N 4 heterostructure achieves an exceptional H 2 evolution rate of 31.6 mmol g –1 h −1, which is 213.6 times and 4.3 times higher than that of pristine Nb 2 O 5 and 2D-C 3 N 4, respectively. Moreover, the champion heterostructure possesses a high apparent quantum efficiency (AQE) of 45.08% at λ  = 405 nm and superior cycling stability. Furthermore, a possible photocatalytic mechanism of the energy band alignment at the hetero-interface is proposed based on the systematical characterizations accompanied by density functional theory (DFT) calculations. This work paves the way for the precise construction of a high-quality heterostructured photocatalyst with efficient charge separation to boost hydrogen production.