Photothermal CO2 conversion to cyclic carbonate over titanium-substituted polyoxometalate within covalent organic frameworks

[Display omitted] •The PTi2W10@EB-TFP has been synthesized by incorporation PTi2W10 into porous structure of EB-TFP.•The PTi2W10@EB-TFP can catalyze CO2 cycloaddition via a photothermal catalytic route.•The crucial role of photogenerated electrons and holes in photothermal catalytic CO2 cycloaddition has been revealed.•The rate determine step of the photothermal catalytic CO2 cycloaddition has been shifted to the cyclization step. The fixation of CO2 with epoxides offers a promising approach for the converting CO2 into valuable chemicals, particularly when driven by the synergistic combination of solar energy and thermal processes. Consequently, the development of innovative and efficient catalysts for photothermal CO2 cycloaddition under visible light irradiation is of critical importance. In this study, we encapsulated titanium-substituted polyoxometalates ([PTi2W10O40]7−, abbreviated as PTi2W10) within covalent organic frameworks (COFs), specifically EB-TFP. The resulting PTi2W10@EB-TFP composite exhibits outstanding performance in photothermal catalytic CO2 cycloaddition, offering a product yield of 98.62 %, which significantly exceeds those obtained with the individual components PTi2W10 (61.39 %) and EB-TFP (50.34 %). In-situ experiments and theoretical calculations indicate that the superior catalytic performance arises from the photothermal catalytic pathway, rather than a synergistic interaction between photocatalytic and thermal pathways. Notably, photogenerated electrons are transferred to PTi2W10, promoting the activation of the epoxide, while the electron-deficient EB-TFP facilitates CO2 activation. This work exemplifies the utilization of polyoxometalates as photothermal catalysts for CO2 cycloaddition, offering a sustainable and efficient strategy to chemical conversion.