Rational design of carbon nitride nanosheet/tube isotype heterojunction for enhanced photocatalytic H2 evolution

Photocatalytic hydrogen production using g-C 3 N 4 is a promising strategy for sustainable energy conversion. Bulk g-C 3 N 4 is limited by easy recombination of carriers and few active sites. To address these issues, constructing heterostructures serves as an effective way to enhance its photocatalytic activity. In this paper, a thermal polymerization method is used to synthesize g-C 3 N 4 nanosheet/tube isotype heterojunction, the photocatalyst with the optimum MU-CN ratio (1:1) exhibits a hydrogen production rate of 165.16 μmol h −1 , about 4.6 times higher than that of bulk g-C 3 N 4 (36.11 μmol h −1 ). Experimental analyses reveal that the distinctive nanosheet morphology leads to a marked rise in specific surface area and generates a large number of exposed active sites, while the band structure difference between CN-M and CN-U establishes an internal electric field that effectively accelerates charge separation and migration. This study emphasizes the importance of isotype heterojunction construction in improving photocatalytic activity.