Single-Crystalline, Ultrathin ZnGa2O4 Nanosheet Scaffolds To Promote Photocatalytic Activity in CO2 Reduction into Methane

Uniform hierarchical microspheres scaffolded from ultrathin ZnGa2O4 nanosheets with over 99% exposed facets were synthesized using an easy solvothermal route with ethylenediamine (en)/H2O binary solvents. Substitution of different chain length amines for en results in no formation of the nanosheet structures, indicating that the molecular structure of En is indispensable for the generation of two-dimensional structures. Inheriting both a high surface area of nanosheets and a high crystallinity of bulky materials allows the unique 3D hierarchical nanostructures to possess great CO2 photocatalytic performance. The normalized time-resolved traces of photo-induced absorption recorded from the nanosheet and meso-ZnGa2O4 indicate that the photo-excited carriers can survive longer on the nanosheet, which also contributes to the high photocatalytic activity of the ZnGa2O4 nanosheets.