Spinel copper ferrite and zinc ferrite films synthesized via solution precursor plasma spray process for functional applications

Binary spinel-type metal oxides (AB(2)O(4)) semiconductors, including ferrites (AFe(2)O(4)), are attractive photocatalysts thanks to their excellent visible light response and good photochemical activity and stability for the photodegradation of organic pollutants. Currently, their synthesis proceeds via conventional chemical routes that follow rather tedious protocols and the final preparations consist in nano-powders, a form that is not exempt of EHS (Environment, health and safety) risks along their handling. From an industry perspective, it is desirable to dispose of an efficient and preferably simple synthesis route capable to produce photocatalytic preparations in a non-dispersible form, for instance in the form of robust films attached on solid substrates. We report herein a single-step method based on the Solution Precursor Plasma Spray (SPPS) process that enables the preparation of promisingly active ferrite-based photocatalytic films, namely CuFe2O4 and ZnFe2O4. We have investigated various types of precursor solutions, including the atomic A/Fe ratios, solvent type and solute concentration, and studied the evolution of the phase composition of the resultant CuFe2O4 and ZnFe2O4 films by XRD. The corresponding surface morphologies and energy bandgaps were also studied by SEM and UV-Vis spectroscopy, respectively. Then the photocatalytic activities of the selective ferrite films were evaluated through the degradation of aqueous solutions of the Orange II dye under different light irradiations. The results of the overall work also revealed that SPPS process represents a fast, one-step, versatile alternative compared to conventional multi-step processes, which is suitable for preparing complex composition metal oxide film-formed photocatalyst.