Selective oxidation of styrene to valuable C7 or C8 aromatics via green photocatalysis with TiO2-based catalysts

The selective oxidation of styrene at its side chains to yield value-added C₇ or C₈ aromatic compounds represents a crucial reaction within the chemical industry. However, achieving precise control over product formation selectivity poses a significant challenge. In this study, we demonstrate the effectiveness of ultra-small nanosized TiO₂-based catalysts in facilitating the selective oxidation of styrene through a mild, eco-friendly photocatalytic approach. Following modification with 0.4% NiO, a notable transformation in product selectivity is observed. The primary products shift from C₈ with 96% selectivity to C₇ with 92% selectivity under UV, and even sunlight-type excitation. Detailed structural and electronic analyses reveal that the incorporation of NiO onto the TiO₂ surface induces the formation of a P-N heterojunction and additional active sites, crucial for promoting C-C cleavage, leading to a selectivity shift from C₈ to C₇ products. This research provides valuable insights into the design of simple TiO₂-based catalysts capable of achieving high selectivity in the oxidation of styrene, highlighting the potential of green photocatalysis in industrial applications.