Abstract
The cancer-causing aromatic volatile organic compound (VOC), benzene, is a common contaminant found in the air. In this study, a reductively engineered palladium (Pd)-copper (Cu) nanoalloy supported on titanium dioxide (TiO 2 ) is prepared to study an exothermic pathway for the rate-limiting benzene ring-opening step via thermocatalytic oxidation. The catalysts are synthesized via wet impregnation, with controlled Pd loading followed by either oxidative (O: air calcination) or reductive (R: hydrogen (H 2 ) treatment at 300°C) pre-treatment. The R pre-treatment generates metallic Pd 0 -Cu 0 nanoalloys on TiO 2 , while the O counterpart yields isolated metal oxides. The ranking of catalytic activity for 100 ppm benzene, under experimental conditions of 250°C, gas hourly space velocity of 79,618 h -1 , and 0% relative humidity, is as follows: Pd/Cu-TiO 2 -R (71 ± 7.9 μmol g -1 h -1 ) > Cu-TiO 2 -R (59 ± 0.27) > Pd/Cu-TiO 2 -O (42 ± 3.4) > Cu-TiO 2 -O (23 ± 0.27). The top-performing Pd/Cu-TiO 2 -R catalyst also achieves the highest CO 2 yield (78.2% across 250 to 550°C). Density functional theory simulations demonstrate the mechanistic origin of this enhancement: the reductively engineered Pd-Cu nanoalloy surface provides an exothermic pathway for benzene ring-opening, whereas the oxidized surface imposes an endothermic barrier. Increased moisture (up to 60% RH) competes with benzene for active sites, reducing benzene conversion from 41.4% to 26.7%. By purposefully creating metallic Pd 0 -Cu 0 interfacial sites on Pd-Cu/TiO 2 nanoalloys through a rational reductive engineering process, this research unlocks an energetically advantageous ring-opening chemical reaction, thereby forging a new design strategy for the oxidation of aromatic VOCs under mild temperature conditions.