CuFeO2 photocatalysts prepared by modified ion exchange method and its applications on hydrogen generation via visible-light-driven water splitting

• Main Authors: KUAN-TING CHIANG, 江冠廷
• Other Authors: Bing-Joe Hwang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/87039752711797007365

碩士 === 國立臺灣科技大學 === 化學工程系 === 99 === CuFeO2 photocatalyst has a band gap of 1.34 eV, where the light of the entire solar spectrum can almost be fully harvested. Thus, the material is considered as one photocatalyst of great potential to utilize and convert solar energy. In literature, the synthesis of CeFeO2 has to be conducted at high temperatures and it is greatly influenced by the calcination atmosphere. Consequently, it is rather difficult to obtain CuFeO2 in pure phase. In this study, weuse Na [EDTA-Fe]．3H2O as the precursor to obtain α-NaFeO2 by thermal decomposition. An Na+-Cu+ ion exchange reaction is successfully employed to transform the prepared α-NaFeO2 into CuFeO2 photocatalystat a relatively low temperature. Crystal structure and size of CuFeO2 synthesized at different conditions were characterized by XRD, SEM and TEM. Optical properties of CuFeO2 were determined by visible-infrared spectrum. Trends in the carrier recombination of CuFeO2 were characterized by photoluminescence spectrum as well. The results showed thathigh crystallinity of the α-NaFeO2 with layer-structuredcan be synthesized by 0.5 g EDFS．3H2O as the precursor under 1 L/min flow of air at 530 ℃. By studying issues associated with the scale-up of the production process, 3 g EDFS．3H2Ocan be further used to the α-NaFeO2 under 1 L/min flow of 70% O2 at 530 ℃. Furthermore, CuFeO2 can be synthesized by Na+-Cu+ ion exchanging α-NaFeO2 with the molten CuCl at 350 ℃. At this temperature, the sintering effect is less dominant than results at at 500 ℃ and 450 ℃. In fact, the highest photocatalytic activity of CuFeO2 can be successfully obtained by dissolved precursor of mixed α-NaFeO2 and β-NaFeO2. Finally, the photocatalytic CuFeO2 has been successfully demonstrated to be capable of generating hydrogen in an aqueous methanol solution. By integrating a Bi20TiO32 as oxygen production catalyst, which is a parallel work from our laboratory, a Z-scheme water splitting system is realized through a twin reactor with copper wire as the electron transfer medium between two chambers. Hydrogen and oxygen can be successfully produced at the photocathode and photoanode chambers in such a twin reactor system, respectively.