Boosted selective photooxidation of methane to methanol on BiS/BiOCl-O 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 (CH) into active chemical fuels such as methanol (CHOH), nevertheless CH oxidation activity and CHOH 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 CH photooxidation. Herein, full-spectrum-responsive BiS/BiOCl-O catalysts with coshared Bi atoms and rich oxygen vacancies (O) were in-situ constructed via anion exchange approach, where BiS served as photo-to-thermal conversion material and concurrently formed S-scheme heterojunction with BiOCl. In-situ generated O in anion-exchange process promoted CH 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 CH oxidation and CHOH production, meanwhile the photoinduced heat by BiS 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-BiS/BiOCl exhibited impressive CHOH 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 CHOH 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 CH to CHOH.