Photocatalytic decomposition of ethanol on TiO2 modified by N and promoted by metals

The photo-induced vapor-phase decomposition of ethanol was investigated on pure, N-doped, and metal-promoted TiO2. The catalysts were characterized by bandgap determination and by FTIR and XPS spectroscopy. In harmony with previous findings, the bandgap of N-doped TiO2 continuously decreased from 3.15 to 2.17 eV with elevation of the temperature of its modification. IR studies revealed that illumination of the C2H5OH–TiO2 system initiated the decomposition of adsorbed ethoxy species to yield acetaldehyde. The photodecomposition of ethanol on pure TiO2 occurs to only a very limited extent; N-doped TiO2 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 TiO2 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 TiO2 dramatically enhanced the extent of photodecomposition of ethanol, even in visible light.