C as a bridge and Bi as a photothermal converter to trigger visible-light catalytic CO2 reduction over BiOBr by in situ solid-state reduction

Abstract

Simultaneously extending the light-harvesting window and accelerating photogenerated carrier migration remains a challenge in photothermal catalytic CO₂ reduction. Herein, BiOBr-based nanosheets (BOB-20) with triple active sites (Bi NPs, amorphous carbon and oxygen vacancies (O_v)) were constructed via in situ solid-phase reduction. Benefiting from the localized surface plasmon resonance (LSPR) effect, Bi NPs can act as electron transport hubs to boost visible light absorption and trigger photothermal effect, thereby elevating the local temperature of catalyst, as well as highly conductive porous C nanoplates as electronic export medium that can speed the separation and transportation of chargers, meanwhile, O_v can promote CO₂ adsorption/activation via enhanced local electron states. Ultimately, BOB-20 achieves a CO generation rate as high as 43.99 µmol g⁻¹ under visible light, which is 3.9 times higher than that of pristine BiOBr (11.15 µmol g⁻¹). This study proposes a green and low-cost solvent-free strategy for CO₂ conversion, from the synthesis of the catalyst to its final application.