Photocatalytic decomposition of ethanol on TiO_2 modified by N and promoted by metals

摘要

The photo-induced vapor-phase decomposition of ethanol was investigated on pure, N-doped, and metal-promoted TiO_2. The catalysts were characterized by bandgap determination and by FTIR and XPS spectroscopy. In harmony with previous findings, the bandgap of N-doped TiO_2 continuously decreased from 3.15 to 2.17 eV with elevation of the temperature of its modification. IR studies revealed that illumination of the C _2H_5OH-TiO_2 system initiated the decomposition of adsorbed ethoxy species to yield acetaldehyde. The photodecomposition of ethanol on pure TiO_2 occurs to only a very limited extent; N-doped TiO_2 displays much higher activity and gives acetaldehyde and hydrogen as the primary products. The acetaldehyde formed is photolyzed to afford methane and CO. The efficiency of the N-doped TiO_2 increased with the narrowing of the bandgap, a feature attributed to the prevention of electron-hole recombination. The deposition of Rh on pure and doped TiO _2 dramatically enhanced the extent of photodecomposition of ethanol, even in visible light.