Photothermal co-removal of NO and toluene over V2O5/TiO2: Mechanistic roles of reactants in light-heat coupling
NH 3 rapidly attenuates photo-assistance efficiency in co-removal of NO and toluene. • NO 2 formation/consumption is rate determining step of photothermal SCR reaction. • Dispersed V 5+ =O sites oxidize both NH 3 , NO and toluene under illumination. • NH 3 -derived radicals attack aromatic rings, inducing phenolic buildup on active sites. • Without mitigating photo-assisted effect attenuation, photothermal deployment increases burdens. V 2 O 5 /TiO 2 -mediated photothermal co-removal of NO and VOCs from incineration flue gas represents a promising energy and emission saving strategy. It is crucial to elucidate the effect of V 2 O 5 loading and to clarify the interaction among reactants during the photothermal catalytic process. Herein, this study elucidates the V 2 O 5 loading effect and provides mechanistic insight into reactant interactions over V 2 O 5 /TiO 2 during photothermal co-removal of NO and toluene. Optimal V 2 O 5 loading increases dispersed V 5+ =O redox and V 5+ –OH adsorption activation sites, while Ti-O-V interfacial motifs modulate the local electronic structure to promote interfacial charge transfer and charge separation. Under photothermal conditions, V 5+ =O sites simultaneously mediate the oxidation of NH 3 and NO, where the formation and consumption of NO 2 serves as the rate-determining step, leading to ineffective accumulation of photogenerated NH 4 + species. In the absence of NH 3 , photogenerated charge carriers promote the initial dehydrogenation of toluene via side-chain activation on V 5+ -OH sites, followed by deep ring-opening degradation mediated by V 5+ =O species. NO reduces the overall toluene conversion but enhances the reaction selectivity toward deep oxidation. When NH 3 and toluene co-exist, radicals derived from NH 3 directly attack the aromatic ring, thereby changing the side-chain oxidation pathway, triggering the formation of strongly adsorbed phenolic intermediates that block catalytic sites. NH 3 does not merely compete with toluene for V-OH adsorption sites, its presence also redirects the toluene oxidation pathway and locks the reaction into a thermally driven regime. This work provides insights into the V 2 O 5 -loading effects and the interaction of reactants in multipollutant photothermal catalysis. Download: Download high-res image (337KB) Download: Download full-size image
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