10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Electric Current-Induced Formation of Defects in Columnar TiO2 Single Crystals under UV Irradiation for Enhanced CO2 Photoreduction
YAO NIE, Pratim Biswas, Washington University in St. Louis
Abstract Number: 309 Working Group: Materials Synthesis
Abstract Carbon dioxide (CO2) capture and utilization is a promising potential technology to address global climate change. Photocatalytic conversion of CO2 into hydrocarbon fuels has attracted abundant research attention in recent years. In this work, columnar titanium dioxide (TiO2) thin films were synthesized by aerosol chemical vapor deposition (ACVD) method and a new method is reported to generate oxygen vacancies and Ti-related defects (OTDs) in these columnar TiO2 thin films under UV irradiation with electric current. The defective TiO2 (TiO2-x) showed a significant enhancement in CO2 photo-reduction. The substrate, electric current, and electric voltage applied played important roles in affecting the photocatalytic performance. The best performing sample showed the highest CO yield of 375 µmol/g/hr, with an apparent quantum efficiency of 0.045%, which was about 4 times higher than that without current (95 µmol/g/hr), and more than 20 times higher than that of TiO2 (P25). A recyclability test demonstrated the reversibility of the OTDs in CO2 photoreduction, with or without an electric current. The formation and healing of OTDs were confirmed by the color change (white to yellow, and back to white) and by HETEM images, UV-vis adsorption, Raman spectra, and XPS spectra. The enhancement of the TiO2-x in CO2 photoreduction with electric current can be attributed to 1) the narrowed band gap energy, 2) the enhanced chemical adsorption of CO2, and 3) the better separation of electrons and holes. This study offers new insights into engineering OTDs in TiO2 for photocatalysis, using an easy and gentle method in ambient environment.