Enhancing the photoelectrochemical activity of a TiO2 thin film with an inverse opal-like structure by a dip coating process

TiO2 thin films with an inverse opal-like structure have attracted considerable attention recently owing to their high potential for a range of applications. In this study, we demonstrated the possibility to deposit TiO2 thin films with an inverse opal-like structure from TiO2 nanoparticle-containing slurry paste using a conventional spin-coating process. Furthermore, we also showed that the photoelectrochemical properties of as-fabricated inverse opal-like TiO2
films can be further enhanced by the dip coating process. In particular, dip-coated and untreated inverse opal-like TiO2 films exhibit photocurrent densities of ~ 66.5 μA/cm2 and ~ 40.9 μA/cm2 at 1.23 V vs. RHE, respectively. A detailed physicochemical analysis revealed that photocurrent density enhancement (~ 62.6%) in dip-coated films can be attributed to a variety of factors including improved interconnection between TiO2 nanoparticles, improved crystallinity, decreased light reflection, and decreased charge recombination. We strongly believe that the proposed methodology can be utilized for the construction of efficient photocatalytic/catalytic systems, gas sensors, and electrochemical sensors.