Gas-solid interfacial photoelectrocatalysis for toluene mineralization with concomitant hydrogen peroxide generation

The abatement of gaseous volatile organic compounds (VOCs) such as toluene is constrained by sluggish mass transfer and the trade-off between adsorption and oxidation activity in conventional liquid-phase systems. Herein, a solid-state paired photoelectrocatalytic system that operates at the gas-solid interface is proposed for enabling simultaneous anodic toluene mineralization and cathodic hydrogen peroxide (H₂O₂) generation under ambient air feed. Particularly, by using a bifunctional composite electrode, in which ethylenediaminetetraacetic acid (EDTA)-modified SnO₂ (E-SnO₂) nanospheres are anchored onto MXene nanosheets, a toluene degradation efficiency of 90.05 ± 3.79% with an exceptional CO₂ selectivity of 97.72 ± 3.57% is achieved alongside sustained H₂O₂ production as a valuable byproduct. Comprehensive analyses reveal that MXene and EDTA synergistically modulate the band structure of SnO₂ for promoting ∙OH generation, while MXene further amplifies this through photoelectric synergy and photothermal effects. In situ tests confirm the complete mineralization without accumulation of toxic intermediates, and theoretical calculations elucidate the increased electron density near the Fermi level, which significantly enhances the adsorption of both toluene and O₂. Hence, this dual enhancement boosts the anodic oxidation kinetics but also facilitates the cathodic reduction reaction, offering a promising pathway for sustainable environmental remediation.