Hollow Au-ZnO/CN Nanocages Derived from ZIF-8 for Efficient Visible-Light-Driven Hydrogen Evolution from Formaldehyde Alkaline Solution

Graphical Hollow N-doped carbon nanocages incorporating Au and ZnO nanoparticles derived from ZIF-8 were synthesized. Au 0.40 -ZnO/CN incorporates Au and ZnO nanoparticles. Under visible light irradiation, Au 0.40 -ZnO/CN exhibits a significantly enhanced H 2 production rate from formaldehyde alkaline solution, which is 12 times and 2.6 times of those of ZnO/CN and Au/CN, respectively. Hollow carbon nanostructured materials incorporating metals or metal oxides have attracted considerable interest in photocatalysis. Herein, novel hollow N-doped carbon nanocages incorporating Au and ZnO nanoparticles derived from ZIF-8 were successfully synthesized. Firstly, ZIF-8 nanocrystals were treated with chloroauric acid solution (HAuCl 4 ) to produce hollow Au X @ZIF-8 cubes through acid etching of cores and cation exchange. Then, the Au X @ZIF-8 cubes were used as precursors to obtain Au X -ZnO/CN after pyrolysis in a N 2 atmosphere. The resulting Au 0.40 -ZnO/CN had a uniform hollow structure with ≈ 30 nm shells conformal to ZIF-8 dimension while incorporating ≈ 5 nm nanoparticles of Au and ZnO and exhibited remarkable photocatalytic activity and excellent recyclability for hydrogen production from formaldehyde (HCHO) alkaline solution under visible light irradiation. The results demonstrated that incorporation of Au greatly improves the visible light absorption and charge separation via SPR effect. Furthermore, the ZIF-8-derived hollow N-doped carbon cages can expose more uniformly disperse active sites with conductive support. The methodology used here provides a novel approach for preparing hollow hybrid carbon materials with visible-light-driven photocatalytic applications.