Millimeter-level nitrogen modified activated carbon spheres assisted Bi4Ti3O12 composites for bifunctional adsorption/photoreduction of CO2

Millimeter-level N-ACSs as desired supporter for immobilizing and tailoring Bi4Ti3O12 can not only increase adsorption ability and active sites for acidic CO2, but also extend visible absorption range and inhibit the recombination of photo-induced charge carriers. The yield of CO evolution for Bi4Ti3O12/N-ACSs is approximately 1.45 times higher than that of pristine Bi4Ti3O12 under simulated sunlight irradiation. [Display omitted] •The incorporation of N into millimeter-level ACSs can undertake super supporter.•N-functional group provides more adsorption/active sites for acidic CO2.•The CO yield of N-ACSs/Bi4Ti3O12 is 1.45 times higher than pristine Bi4Ti3O12.•Enhanced CO2 photoreduction mechanism of N-ACSs/Bi4Ti3O12 is proposed.•New strategy for designing efficient CO2 reduction engineering photocatalyst. The increase of CO2 adsorption and separation efficiency of photo-induced carriers are two crucial factors for achieving effective CO2 reduction into solar fuels. Here, novel millimeter-level nitrogen modified resin-based activated carbon spheres (N-ACSs), as desired support to immobilize and tailor Bi4Ti3O12 catalyst (Bi4Ti3O12/N-ACSs) for improving CO2 photoreduction activities, have been constructed via simple suspension polymerization and impregnation method. The involved TG, FTIR, XRD, XPS, EA, SEM, EDS, N2 adsorption/desorption, CO2 adsorption, UV–vis DRS, MS, PC, EIS, PL spectra and in-situ FTIR were characterized. Bi4Ti3O12/N-ACSs displayed the highest photocatalytic CO2 reduction activity to CO of 142.76 μmol/g under 8 h simulated sunlight irradiation in pure H2O phase, approximately 1.45 times and 1.24 times higher than that of pristine Bi4Ti3O12 and Bi4Ti3O12/ACSs, respectively. The introduction of N-ACSs played four roles: (i) the increase of CO2 adsorption, (ii) the red-shift of optical absorption range, (iii) the consummate separation and transfer of photo-induced carriers, (iv) more CO2 active sites. Finally, the possible mechanism photocatalytic CO2 reduction for Bi4Ti3O12/N-ACSs was proposed. Our findings should provide noteworthy promising strategy to immobilize powder photocatalyst on the surface of millimeter-level carbon spheres for achieving the high-efficient CO2 adsorption and photoreduction to CO.