Three-dimensional C3N5/RGO aerogels with enhanced visible-light response and electron-hole separation efficiency for photocatalytic uranium reduction

Uranium is a critical resource in the nuclear fuel cycle and also a global environmental pollutant with dual effects of radioactivity and chemical toxicity. To ensure the sustainability of environment while meeting future energy needs, reducing soluble U(VI) to relatively immovable U(IV) through photocatalytic technology is an effective strategy to achieve these goals. Here we firstly reported a novel C3N5/reduced graphene oxide (C3N5/RGO) aerogel photocatalyst with 3D macroscopic morphology, and further proved that it is formed form a microscopic 2D/2D nanosheet Mott Schottky heterostructure. The macroscopic 3D morphology of C3N5/RGO aerogel was effective in avoiding the rate-determination step in the uranium enrichment process and the secondary pollution of the environment caused by nanomaterials. The microscopic 2D/2D Mott Schottky heterojunction effectively reduced the electron/hole recombination on the semiconductor surface, thus improving the photocatalytic quantum efficiency. Notably, the U(VI) removal ratio of 3D C3N5/RGO aerogel reached up to 94.9% in the wastewater containing organic matter systems, and it was barely affected by the impurity ions (The content is reached 10 times) and the nuclear radiation (Up to 200 KGy). It is believed that 3D C3N5/RGO aerogel provides a viable solution to treating the wastewater with nuclear radioactivity.