Now-a-days photocatalysis is widely recognized as efficient for pollutants removal, but the largescale application still face challenges. One of the most prominent challenges is the use of photocatalysts (e.g. TiO2, ZnO, etc.) that are activated under UV radiation, which implies additional costs. The need to extend the activation spectral range to the visible region is mainly met by semiconductor doping or coupling with other materials such as other semiconductors, noble metals, and most recently, carbon-based derivatives. The development of photocatalysts usually require expensive, energy intensive processes (sputtering, hydrothermal, etc.), increasing thus the overall costs of the application.
In this context, the photocatalyst approached in this paper is a composite-type material answering to the need of improved photocatalytic effect under combined UV+VIS radiation (simulated solar radiation) consisting of ZnO and carbon derivatives, obtained as thin films by spray pyrolysis deposition, as novel method for this application.
The effect of the zinc precursor (zinc chloride or zinc acetate), of the type and amount of the carbon derivatives (graphene oxide and reduced graphene oxide) and other additives (surfactants, polymers, etc.), as well as the deposition parameters on the thin film properties is discussed. Particular attention is payed to the morphology of the thin films, which is essential to the adsorption stage in the photocatalytic process.
The photocatalytic efficiency of the thin films on the degradation of organic pollutants such as methylene blue and phenol, under solar simulated radiation is presented. The effect of carbon derivatives addition to the oxide thin film is highlighted and is correlated to the effect of thin film morphology and chemical composition. Photocatalytic efficiency, alongside thin film wettability are considered for the purpose of selecting the most promising composite for self-cleaning.