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.