2D/2D Inorganic/Organic Hybrid of Lead-Free Cs2AgBiBr6 Double Perovskite/Covalent Triazine Frameworks with Boosted Charge Separation and Efficient CO2 Photoreduction

Heterojunction construction, especially the inorganic/organic hybrids, is regarded as a universal and effective strategy to achieve high-performance photocatalysts. Herein, a 2D/2D inorganic/organic hybrid photocatalyst was constructed by the electrostatic self-assembly of the lead-free double-perovskite of Cs2AgBiBr6 nanosheets (NSs) and covalent triazine framework (CTF) NSs. The resultant Cs2AgBiBr6/CTF-1 (CABB/CTF-1) hybrid possessed a large surface-to-surface contact area, ensuring intimate interfacial interaction and efficient charge transfer/separation. Meanwhile, the periodical pore structure of CTF-1 endowed the CABB/CTF-1 hybrid with enhanced CO2 adsorption/activation capacity. Consequently, the 2D/2D CABB/CTF-1 hybrid exhibited a remarkable photocatalytic performance toward CO2 reduction. Based on the band structure analysis and various characterization techniques, for example, X-ray photoelectron spectra and electron spin resonance, an S-scheme charge transfer mechanism was proposed. This study presents a new protocol for designing 2D/2D inorganic/organic hybrid photocatalytic systems, which hold great potentials in solar fuel applications.