Isotype heterojunction g-C3N4/g-C3N4 nanosheets as 2D support to highly dispersed 0D metal oxide nanoparticles: Generalized self-assembly and its high photocatalytic activity

Graphitic carbon nitride (g-C3N4) has attracted increasing interest in recent years as a metal-free polymeric photocatalyst for water splitting and degradation of organic pollutants. However, the relatively low photocatalytic activity and serious aggregation of g-C3N4 nanosheets substantially limit its applications. Herein, we propose a generalized and facile bottom-up approach to self-assembly synthesis of isotype heterojunction g-C3N4/g-C3N4 nanosheets/0D metal oxide nanoparticles hierarchical architectures, in which the highly dispersed 0D metal oxide (CeO2 and ZnO as representatives) nanoparticles are anchored on 2D flexible g-C3N4/g-C3N4 heterojunction nanosheets, and the former can be spatially separated by the latter as well. The pyrolysis-induced gases play a critical role in the construction of unique 0D metal oxide/2D g-C3N4/g-C3N4 (metal oxide/CN-UT) hierarchical architectures, which possess improved light harvesting and pollutant adsorption capacity, as well as enhanced separation of photoinduced charge carriers via the three-level electron-hole transfer process owing to the intimate contact between constituents and band alignment among them. As a result, the obtained metal oxide/CN-UT exhibits extraordinary photocatalytic performance under natural sunlight and indoor light illumination. This work demonstrates a generalized bottom-up synthetic method to design efficient composite photocatalysts by adopting integrative nanostructure engineering and a cocatalyst strategy and highlights the promising applications in the field of energy and environment.