Boosted selective photooxidation of methane to methanol on Bi2S3/BiOCl-OV heterojunctions with atomic co-sharing interface via synergy of S-scheme charge transfer and photothermal effect.

Solar-driven photocatalysis offers an energy-saving route for selective conversion of relatively inert methane (CH4) into active chemical fuels such as methanol (CH3OH), nevertheless CH4 oxidation activity and CH3OH selectivity of single photocatalysis are still low. Photothermal synergistic catalysis can maximize the utilization of solar energy to yield charge carriers and synchronously afford heat input, representing a potential strategy for boosting CH4 photooxidation. Herein, full-spectrum-responsive Bi2S3/BiOCl-OV catalysts with coshared Bi atoms and rich oxygen vacancies (OV) were in-situ constructed via anion exchange approach, where Bi2S3 served as photo-to-thermal conversion material and concurrently formed S-scheme heterojunction with BiOCl. In-situ generated OV in anion-exchange process promoted CH4 adsorption and activation. Atomic-level interface channel via cosharing of Bi atoms decreased interfacial resistance and further boosted charge migration. Photogenerated charge carriers with strong redox capacity triggered CH4 oxidation and CH3OH production, meanwhile the photoinduced heat by Bi2S3 harnessing near-infrared light enhanced active species generation and catalysis kinetics. Owing to the synergistic effects of S-scheme charge transfer and photo-to-thermal conversion, the optimal 0.7-Bi2S3/BiOCl exhibited impressive CH3OH productivity of 11.83 mmol/g with high selectivity of 90.2 % after 2 h irradiation of simulated sunlight, significantly outperforming pristine BiOCl (4.01 and 1.98 times) and most recently reported photocatalysts. More than that, the CH3OH productivity reached up to 10.79 mmol/g with a selectivity of 89.5 % under concentrated outdoor natural sunlight. Performance enhancing mechanism was elucidated through in-situ characterizations and DFT calculation. This study provides meaningful guidance to construct photothermal catalysts with high-quality interface for efficient photooxidation of CH4 to CH3OH.