Scalable phase-rich mixed oxide/perovskites: hetero-interfacial tuning catalysed photocatalysis via pH/temperature regulations†

The potential of nanotechnology can move beyond lab scales in one aspect by developing processes for scaling up. Here, the synthesis parameters and conditions for replicable mixed oxide/perovskites of titanium dioxide/strontium titanate (TiO₂/SrTiO₃) with multiple interfaces are demonstrated by adjusting solely the pH of the reaction mixture. Through defect chemistry validations, microscopy-derived nano-to-macro images, and lattice and crystalline structure characterizations, we demonstrate replicability. Aspects fundamental to the development of different phases have been proposed, such as lattice strains, shallow-level exclusive defects, and the presence of grain boundaries between specific phases. For the composite with the highest degree of mixed phase composition, the effects of reaction temperature and time have been investigated. Investigations on these composites for their performance in degradation of Rhodamine B have demonstrated how crucial the ratio of the phases is for catalytic activity. Realizing pristine SrTiO₃ (STO) as well as STO/TiO₂ mixtures without secondary phases like carbonates and possible protocols for achieving Magnéli phases have been demonstrated, making the various compositions intriguing candidates for applications that are concerned with defect and interface engineering that require scaled up protocols for synthesis.