Preparation and Photocatalytic Hydrogen Evolution Performance of C-N Co-doped Nano TiO2 Photocatalysts

Carbon-nitrogen co-doped titanium dioxide (TiO2) nanoparticles were synthesized by calcining titanium carbonitride (TiCN) powder in air at different temperatures. The as-prepared powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet- visible diffuse reflectance spectroscopy (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS). XRD and XPS results showed that nitrogen and carbon in the TiCN lattice could be replaced by oxygen through calcining the TiCN powder in air. Stronger light absorption in both the UV and visible light region was observed for the as-prepared powders compared to commercial P25 from the DRS results. The photocatalytic hydrogen evolution performance over both the as-prepared catalysts and P25 was tested using Na2S-Na2SO3 as a sacrificial electron donor under UV and UV-Vis light irradiation. The highest photocatalytic activity was observed for CN-TiO2 obtained from TiCN and calcined at 550 degrees C. The hydrogen evolution rate reached 41.1 mu mol.h(-1), which is higher than that from P25 (26.2 mu mol.h(-1)). This may be caused by a synergistic effect between doped C and N elements. Under UV-Vis light illumination, the highest hydrogen evolution rate was 0.2 mu mol.h(-1), which may be due to a minor contribution of visible light absorption to water photo-splitting for hydrogen production.