Soft-hard templating solution combustion synthesized CeO2-CuO-TiO2 nanostructures for visible light photocatalysis

Abstract

Given the growing need to address emerging contaminants in water systems, particularly pharmaceutical compounds, there is a pressing demand for advanced and eco-friendly technologies capable of effectively degrading these pollutants. Heterogeneous photocatalysts, especially those based on TiO₂, have shown considerable promise in water purification efforts. However, TiO₂’s efficiency is primarily confined to the ultraviolet region (< 380 nm) due to its large band gap energy (3.2 eV) in the anatase phase. To overcome this limitation and extend the use of TiO₂-based photocatalysts to the visible light spectrum, combining titania with other oxides that are sensitive to visible light has proven to be a successful strategy. Ceria (CeO₂), with its Ce^3 +/Ce⁴⁺ redox pair, enhances photocatalytic activity, while CuO is recognized for its ability to promote visible light responsiveness in TiO₂ catalysts. This study explores a one-pot soft-hard templating Solution Combustion Synthesis (SCS) approach to prepare a series of CeO₂-CuO-TiO₂ nanostructures with different compositions, as effective heterogeneous photocatalysts for visible light-assisted degradation of organic contaminants. The performance of these photocatalysts was investigated both under UV and visible light irradiation, for methylene blue and nalidixic acid degradation, respectively, and compared to those of commercially available TiO₂ nanomaterials used as references. Structural, morphological, textural, and redox analyses demonstrate that the synergistic interaction between the CeO₂ and CuO phases with TiO₂ significantly boosts the photocatalytic performance, particularly under visible light. Notably, the-top performing ternary photocatalyst reached a degradation rate of 62.9 % in 90 min, surpassing the reference TiO₂ P25, which achieved 45 % under the same experimental conditions. The study highlights the potential of SCS as an effective synthetic method for producing nanostructured materials with controlled composition and structure. This approach promisingly addresses the environmental challenge of degrading organic contaminants in water using visible light.