Assisting Bi2Fe4O9 nanosheets with CeO2@PANACSs macro-spheres as bifunctional supporter for enhanced photocatalytic CO2 reduction

The efficient capture of CO2 molecules is a crucial step in the light-driven CO2 synthesis of high value-added products. In this work, CeO2 is embedded in polyacrylonitrile-based carbon spheres (PANACSs) via a suspension polymerization and carbonization method to synthesise CeO2@PANACSs with bifunction (CO2 adsorption and reduction ablity), and the strong oxidising capacity Bi2Fe4O9 was coupled to obtain ternary Bi2Fe4O9/CeO2@PANACSs composites with high adsorption-reduction capacity for CO2. The effective synergistic effects between Bi2Fe4O9 and CeO2@PANACSs realize that the CO yield of ternary hybrid photocatalyst can reach as high as 256.1 μmol g−1 for 10 h, approximately 19.55 times, 1.45 times and 1.62 times higher than that of pristine PANACSs, Bi2Fe4O9 and CeO2, respectively. The exceptional performance of Bi2Fe4O9/CeO2@PANACSs composites is mainly attributed to the synergistic effect of the ternary system, which not only provides CO2-rich adsorption-reduction active sites but also effectively inhibits photogenerated electron-hole complexation. Meanwhile, the outer layer of Bi2Fe4O9 with its excellent oxidising capacity also provides a large amount of H* to ensure efficient hydrodeoxygenation of CO2. Finally, combined with the results of in situ fourier transform infrared spectra, a possible mechanism for the photocatalytic reduction of CO2 over ternary photocatalysts is proposed. Our finding provides a noteworthy promising strategy to construct bifunctional composite photocatalysts for achieving the high-efficient CO2 adsorption and photoreduction to CO.