Structure Modification Function of g-C3N4 for Al2O3 in the In Situ Hydrothermal Process for Enhanced Photocatalytic Activity

Heterojunctions of g‐C3N4/Al2O3 (g‐C3N4=graphitic carbon nitride) are constructed by an in situ one‐pot hydrothermal route based on the development of photoactive γ‐Al2O3 semiconductor with a mesoporous structure and a high surface area (188 m2g−1) acting as electron acceptor. A structure modification function of g‐C3N4 for Al2O3 in the hydrothermal process is found, which can be attributed to the coordination between unoccupied orbitals of the Al ions and lone‐pair electrons of the N atoms. The as‐synthesized heterojunctions exhibit much higher photocatalytic activity than pure g‐C3N4. The hydrogen generation rate and the reaction rate constant for the degradation of methyl orange over 50 % g‐C3N4/Al2O3 under visible‐light irradiation (λ>420 nm) are 2.5 and 7.3 times, respectively, higher than those over pristine g‐C3N4. The enhanced activity of the heterojunctions is attributed to their large specific surface areas, their close contact, and the high interfacial areas between the components as well as their excellent adsorption performance, and efficient charge transfer ability. Better together: A structure modification function of g‐C3N4 (graphitic carbon nitride) for Al2O3 in the hydrothermal preparation process is found and highly efficient g‐C3N4/Al2O3 heterojunctions are constructed by an in situ route, which results in large specific surface areas, close contacts and high interfacial areas between the components. The defect sites of Al2O3 act as acceptors of photo‐induced electrons from g‐C3N4 (see figure), which contributes to an enhanced photocatalytic activity of g‐C3N4.