Nguyen, T.-V.T.-V.NguyenWu, J.C.S.J.C.S.WuJEFFREY CHI-SHENG WU2018-09-102018-09-102008http://www.scopus.com/inward/record.url?eid=2-s2.0-44149085158&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/338745An optical-fiber reactor is employed to photocatalytically reduce CO2 with H2O to fuels under UVA artificial light and concentrated natural sunlight. The optical fiber is coated with gel-derived TiO2-SiO2 mixed oxide-based photocatalysts. Fe atom is found to insert into the TiO2-SiO2 lattice during sol-gel process, resulting in the full visible light absorption as well as the effect on product selectivity of the derived catalyst. Under UVA, ethylene is mainly produced on Cu-Fe/TiO2 catalyst with the quantum yield of 0.0235%, whereas Cu-Fe/TiO2-SiO2 catalyst is observed to favor methane production with the quantum yield of 0.05%. Meanwhile, the overall energy efficiency is found to be much higher on Cu-Fe/TiO2-SiO2 (0.0182%) than on its Cu-Fe/TiO2 counterpart (0.0159%). There is only methane evolved over both bare TiO2-SiO2 and Cu-Fe/TiO2-SiO2 catalysts under natural sunlight with the production rates of 0.177 and 0.279 μmol/g-cat h, respectively. For the former catalyst, the increase in light intensity is not found to compensate the inherent electron-hole recombination in the TiO2-SiO2-acac catalyst, whereas the superior photoactivity of Cu-Fe/TiO2-SiO2 catalyst under natural sunlight could be ascribed to its full absorption of visible light. © 2008 Elsevier B.V. All rights reserved.Carbon dioxide; Optical fiber; Photocatalytic reduction; Solar energy; TiO2[SDGs]SDG7Carbon dioxide; Light absorption; Optical fibers; Photocatalysis; Photocatalysts; Reduction; Sol-gel process; Photocatalytic reduction; Photoreduction; Product selectivity; Fuelsjournal article10.1016/j.solmat.2008.02.010