Structure and composition study of carbon-doped titanium oxide film combined with first principles

Carbon-doped titanium oxide (C/Ti-O) films were prepared on Si(100) wafer, stainless steel (type 304) and glass by reactive magnetron sputtering (RMS) using CO2 gas as carbon and oxygen source under room temperature (RT). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to analyze structure and composition of the as-prepared C/Ti-O film. It could be observed from XRD that the as-prepared C/Ti-O film contained TiO crystal phase structure. Ti2p XPS spectrum of the as-prepared C/Ti-O film showed that the valences of titanium were made up of Ti2+, Ti3+ and Ti4+. C1s XPS spectrum revealed that carbon was doped into titanium oxide based on the existence of the typical Ti-C bond. The optical absorption curve by ultraviolet-visible (UV-Vis) spectrophotometer showed that the C/Ti-O film appeared the remarkable red shift of absorption edge, which contributed to C substitution in O sites in amorphous TiO2. Photocatalysis test using methyl orange (MO) as indicator confirmed that the as-prepared C/Ti-O film had photocatalytic activity. Combined with the results of the tests and first-principles calculations, a potential photocatalysis mechanism was proposed.