The photoinduced vapor-phase decomposition of methyl formate was investigated on pure and on Pt-metals-promoted TiO2. Infrared spectroscopic studies revealed that illumination induced the dissociation of molecularly adsorbed methyl formate to formate on pure TiO2 even at ∼186 K. This process is indicated by the appearance of the absorption band at 1580-1590 cm-1 due to asymmetric stretch of formate species. The extent of the dissociation is increased with the time of irradiation. Deposition of Pt metals on TiO2 only slightly influenced this process. The photocatalytic decomposition of methyl formate vapor on pure TiO2 occurred to only a limited extent at 300 K, but the deposition of Pt metals on TiO2 appreciably enhanced the extent and the rate of photodecomposition. Nevertheless the photocatalytic reaction of methyl formate proceeded more slowly compared to that of formic acid on the same catalysts, and produced more CO. Addition of H2O to the methyl formate decreased the CO/H2 ratio by a factor of 4. When the bandgap of TiO2 support was lowered by N-doping from 3.02 to 1.98 eV, the photocatalytic activity of metal/TiO2 catalysts appreciably increased, and the decomposition of methyl formate was observed even in visible light.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films