Carbon-doped ZnO nanostructures synthesized using vitamin C for visible light photocatalysis

We report the synthesis of carbon-doped zinc oxide nanostructures using vitamin C, and their visible light photocatalytic activity. Amorphous/crystalline vitamin C-ZnO (VitC-ZnO) structures were obtained from a solution of zinc nitrate hexahydrate, HMT, and vitamin C through heating at 95 degrees C for 1 h. VitC-ZnO structures were calcined in air at 500 degrees C for 2 h to create C-doped ZnO nanostructures. Calcined structures were polycrystalline, with an average crystal domain size of 7 nm. EDS, XPS, and XRD analysis revealed the substitution of oxygen with carbon and the formation of Zn-C bonds in the C-doped ZnO nanostructures. The carbon concentrations, in the form of carbide, were controlled by varying the concentrations of vitamin C (more than 1 mM) added to reaction solutions. On the basis of these experimental results, we propose a possible formation mechanism for C-doped ZnO nanostructures. The C-doped ZnO nanostructures exhibited visible light absorption bands that were red-shifted relative to the UV exciton absorption of pure ZnO nanostructures. The visible light (lambda >= 420 nm) photocatalytic activities of C-doped ZnO nanostructures were much better than the activities of pure ZnO nanostructuresclose576

The effects of vitamin C on ZnO crystal formation

We have studied the effects of L(+)-ascorbic acid (vitamin C) on the formation of ZnO crystals. We carried out a series of experiments under weak acidic to alkaline conditions. We obtained ZnO structures with various distinct morphologies by varying the concentration of vitamin C dissolved in the weak acidic and alkaline solutions. Under weak acidic conditions, if the concentration of added vitamin C exceeds 0.5 mM, mixed amorphous/crystalline vitamin C-ZnO (VitC-ZnO) nanostructures are obtained. We also found that the ZnO content of the VitC-ZnO nanostructures can be controlled by adjusting the concentration of vitamin C added to the reaction solution. On the basis of our results, we propose a mechanism for the formation of the various ZnO structures and VitC-ZnO nanostructures in the presence of vitamin C