2D/3D- C3N4/CeO2 S-scheme heterojunctions with enhanced photocatalytic performance

Abstract

• Successfully developed a novel method to obtain g-C 3 N 4 /CeO 2 composite photo-catalysts via simple, ball milled thermal spreading technique. • Facile control of surface morphology of carbon nitride on ceria. The optical absorption is tuned by morphology control. • The optimum loading was found to be 7.5 wt. %. • Morphology with an intermediate thickness between very thin and bulk carbon nitride on ceria surface is important to achieve maximum efficiency. • High efficiency of methylene blue degradation and good recycling performance. A facile, green and easily scalable method has been developed to facilitate the construction of 2D-C 3 N 4 /3D-CeO 2 heterojunction materials. It uses only cheap urea and ceria in a thermal spreading technique that allows the controlled growth of carbon nitride layers on cerium oxide surface. The exfoliation of bulk carbon nitride and subsequent stabilization of layers on ceria takes place during thermal spreading technique in a single step. Simple variation of carbon nitride allowed to control the morphology of carbon nitride from highly dispersed thin layer up to bulk-like structures over ceria surface. The optical absorption was enhanced with 2D-C 3 N 4 /3D-CeO 2 materials. The variation of structure and consequent differences in the solar powered decomposition of methylene blue has been analyzed. Results reveal that, the optimum loading of 7.5 wt.% carbon nitride can lead to the formation of intermediate structure in between very thin layers and bulk-like structure, that achieves best contact between the two phases making effective heterojuctions. This best catalyst exhibits 98% conversion at a timing of 100 minutes. The radical scavenging studies showed that •O 2− and h+ performed an imperative role. In addition, a plausible mechanism of photo catalytic decomposition is also proposed for 2D-C 3 N 4 /3D-CeO 2 materials.