Chloroplast-inspired microenvironment engineering of inverse opal structured IO-TiO2/Chl/IL for highly efficient CO2 photolytic reduction to CH4

Low CO2 capture and sunlight utilization, rapid recombination of photocarriers restrict application of TiO2 photocatalyst in CO2 photoreduction. Herein, inverse opal structured IO-TiO2/Chl/IL with chloroplast-inspired microenvironment was constructed to achieve the synergistic effect of CO2 capture and light-reaction system for efficient photoreduction CO2 to CH4. Ionic liquid ([BMIM][BF4]) coated on Chl(Cu)/TiO2 surface through Ti-F bond resembled the CO2 capture function of stroma in chloroplast, while TiO2 combined with Chl(Cu) to mimic the light-reaction system of thylakoid in chloroplast, these two parts imitating chloroplast microenvironment. The photonic band tuning of IO-TiO2/Chl/IL to overlap Chl(Cu) visible absorption band, enhancing light utilization of IO-TiO2/Chl/IL by slow photon effect. [BMIM][BF4] and Chl(Cu) coordinated with TiO2 significantly promoted electron transfer ability, redox ability and photogenerated carriers separation of IO-TiO2/Chl/IL. IO-TiO2/Chl/IL exhibited excellent photocatalytic performance (44.9 μmol·g−1·h−1) with high CH4 selectivity (93%), providing a biomimetic chloroplast microenvironment strategy with high efficiency photocatalytic CO2 reduction.