Full-spectrum CO2 photoreduction over nickel phytate-modified lead-free perovskite.

Photocatalytic CO2 reduction coupled with water oxidation provides a sustainable route for solar fuel production, but its efficiency is limited by insufficient near-infrared light utilization, rapid carrier recombination and weak CO2 activation. Herein, biomass-derived nickel phytate (PA-Ni) was immobilized on lead-free double perovskite Cs2AgBiBr6 (CABB) to construct a full-spectrum-responsive photocatalyst for gas-solid CO2 photoreduction without sacrificial reagents. PA-Ni extends the optical absorption of CABB into the near-infrared region and introduces surface Ni sites for CO2 adsorption and activation. The optimized PA-Ni@CABB(1:1) composite achieved a CO evolution of 54.9 μmol g-1, approximately 2.5- and 6-fold higher than pristine CABB and PA-Ni. More importantly, PA-Ni@CABB(1:1) exhibited distinct near-infrared-driven CO2 reduction activity with a CO yield of 16.3 μmol g-1 under λ ≥ 800 nm irradiation, while both individual components were almost inactive. Systematic experiments and density functional theory calculations reveal that interfacial electron transfer accelerates charge separation, favors CO2 adsorption and *COOH generation, thereby accounting for the enhanced CO2 photoreduction activity. This work provides a biomass-based interfacial modification strategy for designing lead-free perovskite photocatalysts with broadened solar utilization.