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

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.