Photooxidation of Formic Acid vs Formate and Ethanol vs Ethoxy on TiO₂ and Effect of Adsorbed Water on the Rates of Formate and Formic Acid Photooxidation

Abstract

Comparison of photooxidation rates of formic acid and formate on TiO 2 as well as the effect of adsorbed water on formate and formic acid photodecomposition rates have been investigated by Fourier transformed infrared spectroscopy. Adsorbed formic acid and formate are all photooxidized to CO 2 in O 2 . Formic acid on TiO 2 shows a photoreaction rate that is roughly 53 times that of formate groups for a same surface concentration. The presence of H 2 O can increase formate and formic acid photooxidation rates by a factor close to 2. In addition, photochemistry of adsorbed ethanol and ethoxy is also compared. It is found that ethanol is important for the formation of acetaldehyde, while ethoxy groups are photooxidized to adsorbed acetate, formate, and water. Possible reasons for these differences are discussed.

Novel and facile synthesis of transparent-monolithic TiO2 gels by sol-gel method based on an esterification reaction

“…(1720 cm −1 ) forms [26]. Based on the above results, we suggest that we now have a polymeric titanuim acetate, such as Ti[(OH) y (OOCCH 3 ) x ] much less reactive species, with x and y between 0 and 2, from which all OC 3 H 7 groups have completely disappeared (942 cm −1 ) [27].…”

Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study

“…6 Formate adsorption on TiO 2 has been studied extensively. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] Previous studies of adsorption of formic acid (HCOOH) on rutile TiO 2 (110) surfaces have shown that upon adsorption it dissociates into a formate ion (HCOO -) and a proton (H + ), which bind to lowcoordinated Ti and O surface atoms, respectively. 22,23 The adsorption structure of small molecules, such as HCOOH, can be studied favourably by infrared spectroscopy, and in particular infrared reflection-absorption spectroscopy (IRRAS) has been employed to study e.g.…”

Adsorption and reactions of CH2Br2 on TiO2: Effects of H2O and O2

“…Figure 5 shows the spectra taken before and after the indicated times during photoirradiation of adsorbed CH 2 [14]. Likewise, photooxidation of HCOO (a) on TiO 2 in O 2 produces CO 2 [11]. Figure 6 shows the spectra taken before and after the indicated times during photoirradiation of a …”