Photocatalytic decomposition of formic acid and methyl formate on TiO2 doped with N and promoted with Au. Production of H2

Abstract

Abstract The photo-induced vapor-phase decompositions of formic acid and methyl formate were investigated on pure, N-doped and Au-promoted TiO 2 . Infrared (IR) spectroscopic studies revealed that illumination initiated the decomposition of adsorbed formate formed in the dissociation of formic acid and located mainly on TiO 2 . The photocatalytic decompositions of formic acid and methyl formate vapor on pure TiO 2 occurred to only a limited extent. The deposition of Au on pure or doped TiO 2 markedly enhanced the extent of photocatalytic decomposition of formic acid. The main process was dehydrogenation to give H 2 and CO 2 . The formation of CO occurred to only a very small extent. Addition of O 2 or H 2 O to the formic acid decreased the CO level from ∼0.8% to ∼0.088%. Similar features were experienced in the photocatalytic decomposition of methyl formate, which dissociated in part to give surface formate. Experiments over Au deposited on N-doped TiO 2 revealed that the photo-induced decomposition of both compounds occurs even in visible light.