Tuning TiO₂/Co₃O₄ Nano-interface for bridging photo- and plasma-catalytic reactive oxygen species generation

Photo-plasma catalysis, combining the controllability of photocatalysis with the high reactivity of plasma, presents a promising platform for reactive oxygen species (ROSs) generation. However, efficient coupling of photocatalysis and plasma requires interfaces that integrate multiple catalytic functions to reconcile differences between the two processes. Herein, we report the tuning of the TiO₂/Co₃O₄ nano-interface for efficient photo-plasma catalytic ROS generation by loading a Co₃O₄ nanozyme onto a surface-disordered TiO₂ photocatalyst. For bisphenol A (BPA) removal, the composite catalyst achieves a degradation rate that is 17.3-fold and 12.6-fold higher than those of plasma and photocatalysis alone, respectively. Combined ROS scavenging and probe analyses reveal that the enhanced bisphenol A removal is directly related to the efficient singlet oxygen (¹O₂). Further mechanistic analyses suggest that the yield of ¹O₂ is linked to the conversion of superoxide radicals (•O₂^-). The heterogeneous nano-interface serves as the key reaction center. Specifically, surface disorder and heterojunction-driven electron accumulation promote •O₂^- generation via photocatalytic O₂ reduction on TiO₂, while holes in Co₃O₄ oxidize plasma-generated H₂O₂ to •O₂^- through a sustained Co³⁺/Co²⁺ redox cycle. Compared with TiO₂/Fe₂O₃ and TiO₂/CuO, TiO₂/Co₃O₄ exhibits superior photo-plasma catalytic performance due to the more efficient conversion between H₂O₂ and •O₂^- enabled by the stable Co³⁺/Co²⁺ redox cycle. This work provides a general paradigm for developing interfacial reaction centers in catalysts to improve coupled catalytic ROS generation.