Carbon-doped In2O3 films for photoelectrochemical hydrogen production

Carbon-doped In2O3 films were synthesized by spray pyrolysis and evaluated for photoelectrocatalysis. All C-doped films showed cubic structure, and XPS confirmed carbon's presence and content. 13C SSNMR showed the presence of carbonate-type species. C-doped In2O3, compared to undoped, showed increased absorption in the 350–500 nm range with a red shift in the band gap transition. The photoactivity was evaluated under near-UV and visible light irradiation. The C-doped films exhibited photocurrent densities up to 1 mA/cm2, with a high contribution (40%) from visible light irradiation. Under the same irradiation conditions, C-doped In2O3 produced much greater photocurrent densities than the undoped films. Photocurrent densities of the C-doped films were determined as a function of the dopant source, its concentration, and film thickness. These results indicate the potential for further development of In2O3 photocatalysts, and provide useful information towards understanding the structure and enhanced photoelectrochemical properties of these new materials.