Effect of carbon and oxygen on phase transformation of annealed titania films

• Main Authors: Po-Wen Chou, 周博文
• Other Authors: Ming-Show Wong
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/48983640529057934374

碩士 === 國立東華大學 === 材料科學與工程學系 === 96 === Abstract It was reported recently that mixed phases (anatase and rutile) of titania could enhance photocatalysis, so how to create mixed phases of titania has become an important issue. Carbon-containing titania films (C-TiO2) have also exhibited great potential as photocatalyst working under visible light irradiation in our previous work. Carbon would serve as a light sensitizer and carbon dopant in titania could narrow its bandgap and both effects could improve the photocatalytic performance of C-TiO2 under visible light. In this investigation, we have observed that free carbon in titania film helps to create oxygen vacancies during annealing in vacuum that facilitates rutile formation. Carbon-containing titania films were prepared by reactive magnetron sputtering from co-sputtering Ti metal and graphite targets. Parallel study of thermal annealing effect on amorphous titania films with and without carbon addition were carried out and compared. Amorphous C-TiO2 and amorphous TiO2 were both annealed in vacuum and in air. C-TiO2 films of various oxygen content were prepared by modulating oxygen flow rate during deposition and annealed in air to differentiate how the effect of oxygen defects on phase transformation of titania. All the results showed that oxygen defects play an important role in phase transformation. Carbon reacts with oxygen in titania films that creates oxygen deficient titania and helps rutile phase formation via thermal annealing.