Quenching-Derived Pt Clusters on Co₃O₄/TiO₂ p-n Heterojunctions Enable Efficient Photothermal Oxidation of VOCs

Photothermal catalysis provides an effective strategy to overcome the high energy consumption of thermal catalysis and the low efficiency of photocatalysis; however, inefficient charge separation and limited O₂ activation remain key challenges. Herein, a p-n heterojunction oxide support, Co₃O₄/TiO₂, was constructed and decorated with Pt species via a quenching method. The resulting Co₃O₄/TiO₂-Q-Pt catalyst achieved toluene conversion exceeding 90% within 38 min under light irradiation at 522 mW cm^{- 2}, significantly outperforming single-component oxide-supported catalysts. The catalyst exhibited excellent photothermal stability and strong resistance to water vapor and mixed volatile organic compound (VOC) conditions. Structural characterization revealed that Co₃O₄ incorporation reduced TiO₂ crystallinity while enhancing lattice-oxygen mobility, redox capability, and light absorption, even at low Co₃O₄ contents. Moreover, electron paramagnetic resonance (EPR) measurements showed enhanced generation of •OH and •O₂ ^- species under illumination, consistent with improved photoinduced redox activity. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed suppression of the accumulation of partial-oxidation intermediates and promotion of the formation of benzoate and maleic anhydride species, thereby facilitating aromatic ring cleavage and deep mineralization of toluene.