Systematic study of sol-gel parameters on TiO₂ coating for CO₂ photoreduction

An optimized sol-gel method for TiO₂ coating was developed for CO₂ photoreduction using a systematic Design of Experiments (DOE) approach and an efficient Plackett-Burman (PB) design. Conducting fifteen experiments, the effects of seven sol-gel process parameters were investigated on four catalytic properties for CO2 photoreduction: band gap, catalyst coverage, anatase crystallinity and ratio anatase:rutile. The PB design results yielded a wide range for the catalyst’s properties: band gap (1.86–3.35 eV), coverage (11.53–99.63%), anatase crystallinity (0–48.5 nm) and ratio anatase:rutile (1:0 and 0:1). Machine vision using manual global, Otsu global and adaptive thresholding were compared for estimating the coverage of catalyst on a glass slide support.