Photocatalytic Properties of a Novel Keratin char-TiO2 Composite Films Made through the Calcination of Wool Keratin Coatings Containing TiO2 Precursors

Abstract

In this study, the photocatalytic properties of novel keratin char-TiO2 composite films, made through the calcination of wool keratin coatings containing TiO2 precursors at 400 °C, were investigated for the photodegradation of organic contaminants under visible light irradiation. Its structural characteristics and photocatalytic performance were systematically examined. It was shown that a self-cleaning hydrophobic keratin char-TiO2 composite film containing meso- and micro-pores was formed after the keratin—TiO2 precursors coating was calcined. In comparison with calcinated TiO2 films, the keratin char-TiO2 composite films doped with the elements of C, N, and S from keratins resulted in decreased crystallinity and a larger water contact angle. The bandgap of the char-TiO2 composite films increased slightly from 3.26 to 3.32 eV, and its separation of photogenerated charge carriers was inhibited to a certain degree. However, it exhibited higher photodegradation efficiency to methyl blue (MB) effluents than the pure calcinated TiO2 films. This was mainly because of its special porous structure, large water contact angle, and high adsorption energy towards organic pollutants, confirmed by the density functional theory calculations. The main active species were 1O2 radicals in the MB photodegradation process.

Selective Photocatalytic Activities of Amino Acids/Peptide-Ti3C2Tx-TiO2 Composites Induced by Calcination: Adsorption Enhancement vs Charge Transfer Enhancement

“…After calcination in a nitrogen environment, the exposed peptide chains of wool keratin on/near the surface of the CP-T-T composite are carbonized with the loss of F and S elements, resulting in good electrical conductivity. It has been proved that the hydrophobic features can be obtained when the keratin-TiO 2 composite is calcined and many meso- and micropores are formed, exhibiting higher photodegradation efficiency to organic pollutants than the pure calcinated TiO 2 because of its special porous structure, large water contact angle, and high adsorption energy . Moreover, more nanopores are produced as confirmed by BET results, which are favorable for the physical absorption of dye molecules.…”