Efficient photocatalytic hydrogen evolution by in situ construction of Nb4+ charge-carrier channels in hollow porous tubular C3N4 and Nb2O5 Z-scheme heterojunctions

Optimizing heterojunction structure is an important way to improve photocatalytic activity. Herein, we report a novel hollow tubular C3N4/Nb4+/Nb2O5 3 N 4 /Nb 4+ /Nb 2 O 5 nano- particle Z-Scheme heterojunction, by introducing Nb4+ 4+ ions into Nb2O5 2 O 5 through a reducing atmosphere during C3N4 3 N 4 thermal polymerization. The optimized heterostructure showed outstanding photocatalytic hydrogen evolution activity under both UV-vis (14.93 mmol g- 1 h-1)-1 ) and Vis (5.22 mmol g- 1 h-1)-1 ) lights. The photocatalytic hydrogen evolution activity under UV-vis light is 26.6 and 4.75 times that of bulk C3N4 3 N 4 (CN) and hollow tubular C3N4 3 N 4 (HCN), respectively. The increased photocatalytic activity can be attributed to the larger specific surface area, more active sites, and enhanced light absorption capacity of the composite. Crucially, the introduction of Nb4+ 4+ ions as the charge-carrier transport channels in the Z-scheme heterostructure improves the efficiency of photogenerated charge- carrier separation. This study provides a useful design strategy for Z-Scheme photocatalytic heterojunction structures that can utilize solar light more efficiently.