Construction of g-C 3 N 4 /Al 2 O 3 hybrids via in-situ acidification and exfoliation with enhanced photocatalytic activity

Homogeneous ultrathin g-C3N4 nanosheets/Al2O3 heterojunctions are synthesized using melamine and Al(NO3)3 via in-situ reaction and the following thermal polymerization approach. The in-situ reaction between melamine and Al(NO3)3 results in the existence of HNO3-acidified melamine and Al(OH)3 aggregates via the hydrolysis of Al(NO3)3. After thermal polymerization, the aggregates are converted to g-C3N4/Al2O3 composites. The thermal polymerization of acidified melamine and the support effect of aluminum hydroxide for g-C3N4 during the calcination process lead to highly dispersed amrophous Al2O3 on ultrathin g-C3N4 nanosheets, which is beneficial for the separation of photogenerated electron-hole pairs in the heterojunction. The degradation rate for Rhodamine B (RhB) over the most activie sample is 16.6 times than that of pristine g-C3N4 under visible light irradiation, which can be attributed to the high specific surface area, highly dispersion of amorphous Al2O3 on ultrathin g-C3N4 nanosheet, and the effective electrons transfer from g-C3N4 to the amorphous Al2O3.