Photocatalytic efficiency tuning by the surface roughness of TiO 2 coatings on glass prepared by the doctor blade method

TULLI, FIORELLA; MORALES, JESÚS M.N.; SALAS, ESTEBAN E.; MORÁN VIEYRA, FAUSTINO E.; BORSARELLI, CLAUDIO D.

PHOTOCHEMISTRY AND PHOTOBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020

0031-8655

A set of opaque TiO2 films of the Degussa P25 or Hombikat UV100 powders were prepared by the doctor blade method on glass slides as a function of the amount of polyethylene glycol of 20 kDa (PEG20), and they were characterized by spectroscopy, microscopy, and photochemical kinetics measurements. After annealing treatment at 450 °C, about 5-7% C atom from the organic complexing agents (CA) was incorporated into the film?s inducing a small reduction of the energy band gap of TiO2 (i.e. 3.02  Eg (eV)  3.08). All films were about 15  2 m thick but their micro-morphological characteristics depended on the content of PEG20, showing different patterns of cracks and aggregates that produce intense light scattering and re-transmission phenomena with the result of a three-dimensional excitation of the TiO2 particles in the thick film. Back-face excitation with UVA light (365  42 nm) of the opaque films in contact with an aqueous solution produced both surface-bound and free hydroxyl radicals, as detected using a coumarin solution as the radical dosimeter. The observed photocatalytic quantum efficiency decreased with the surface roughness of the films, indicating a surface morphological control on the generation of hydroxyl radicals