Adsorption and photo-oxidation of acetaldehyde on TiO2 and sulfate-modified TiO2: Studies by in situ FTIR spectroscopy and micro-kinetic modeling

Abstract

Adsorption and photocatalytic oxidation of acetaldehyde have been investigated on TiO 2 and sulphate-modified TiO 2 films (denoted SO 4 -TiO 2 ). In situ Fourier transform infrared spectroscopy was used to study surface reactions as a function of time and number of experimental cycles. Spectral analysis and micro-kinetic modelling show that crotonaldehyde formation occurs spontaneously on TiO 2 but is impeded on SO 4 -TiO 2 , where instead acetaldehyde desorption is significant. Photo-oxidation yields significant amounts of formate on TiO 2 , and was identified as the rate-determining step and associated with site blocking.Significantly smaller amounts of formate were observed on SO 4 -TiO 2 , which is due to the acidity of this surface resulting in weaker bonding of aldehyde and carboxylate intermediate species. Our results are of considerable interest for applications to photocatalytic air purification and to surfaces with controlled wettability.

Acetaldehyde adsorption and condensation on anatase TiO2: Influence of acetaldehyde dimerization

“…After coating, the samples were left to dry overnight, and were subsequently sintered at 500 °C for 1 h prior to use. A more detailed characterisation of TiO 2 films prepared in this manner has been presented elsewhere [31].…”

“…Repeated FTIR spectra were acquired with 2 cm -1 resolution once per minute, corresponding to can be found elsewhere [31]. The spectra were baseline-corrected and transferred to the R program environment for further analysis [34].…”

“…With these choices of integration ranges the influence of variations of surface water bands in the 1615-1620 cm -1 is avoided. The conversion of the FTIR absorbance to coverage was done in two steps [31]. First, the maximum coverage for both species was determined.…”

“…In many applications it is desirable to suppress formation of species with higher mass, such as in photocatalytic air cleaning. It has been recognized that condensation can be suppressed by supporting the catalyst on a noble metal support [22], or increasing the surface acidity through SO 4 modification [31].…”

Photocatalytic and photoelectrocatalytic degradation of small biological compounds at TiO2 photoanode: A case study of nucleotide bases

“…Photocatalytic (PC) degradation of a wide spectrum of organic compounds via TiO 2 photocatalysis has been well studied and documented [1][2][3][4][5]. Successful demonstration of the ability of illuminated TiO 2 for disinfection and decomposition of microorganisms has led to a new application field of TiO 2 photocatalysis [6][7][8][9][10][11].…”