“…[11][12][13][14][15] However, bulk C 3 N 4 (BCN) still suffers from inferior photocatalytic efficiency owing to its low charge separation and transfer, insufficient light absorption and low specific surface area, limiting its further development. 16,17 Aiming at compensating the intrinsic drawback of g-C 3 N 4 to enhance its photocatalysis, many strategies like nanostructure design, electronic structure modulation, crystal-structure engineering, and heterostructure construction have been developed, 16,[18][19][20][21] among which electronic structure modulation can be considered as one of the most crucial and effective approaches to improve the photocatalytic efficiency of g-C 3 N 4 . 20,[22][23][24] Although many efforts to modulate electronic structure of g-C 3 N 4 to 5 incorporated g-C 3 N 4 tubes, showing a 30 times higher HER than BCN.…”