A strategy for synergistic photothermal-photocatalytic: contactless photocatalytic reactor for CO2 reduction with seawater or wastewater into HCOOH

Herein, a synergistic photothermal-photocatalytic strategy is developed by designing a contactless photocatalytic reactor that concurrently synchronizes and enhances mass transfer while expanding the scope of usable water sources. Specifically, heat radiation-induced evaporation is exploited to accelerate the transport of both reactants and products, thereby relaxing the purity requirements for the water feedstock and sustaining efficient CO 2 reduction rates even with seawater and wastewater. Importantly, the contactless gas-phase configuration is expected to reduce the mass-transfer mismatch between CO 2 and H 2 O by bringing both reactants into the gas phase, where their diffusion coefficients are of the same order of magnitude. Under full-spectrum irradiation in a reactor with a 1 cm 2 irradiation area, the CO 2 -to-formic acid production rates using pure water, simulated seawater, and simulated wastewater reach 680.7, 645.3, and 663.0 μmol g −1  h −1 . This work not only demonstrates the valorization of wastewater resources but also opens a new avenue for integrated photocatalysis and photothermal conversion.