Preparation of hierarchical g-C3N4@TiO2 hollow spheres for enhanced visible-light induced catalytic CO2 reduction.

• HCNS@TiO 2 fabricated by nanocasting method and kinetically-controlled coating. • This engineered photocatalyst showed a valuable performance for CO 2 conversion. • The obtained CH 3 OH and CH 4 photoproductions are 11.3 and 4.6 μmol/gcat.h. • The tailored photocatalyst showed excellent stability during five subsequent runs. Hierarchical g-C 3 N 4 @TiO 2 hollow sphere with excellent photocatalytic activity for CO 2 reduction under the visible light was prepared by assembling TiO 2 shell onto the surface of hollow carbon nitride sphere (HCNS). This engineered photocatalyst was prepared by a two-step process: at first, the process of nanocasting was done by a templating method, followed by the kinetically-controlled coating technique. Specifically, mesoporous silica sphere and cyanamide were used as sacrificial template and precursor of carbon nitride, respectively, for the synthesis of hollow carbon nitride sphere which was further modified with titanium dioxide nanosheets. The remarkable photocatalytic activity of as-prepared nanocomposite could be attributed to its special structure, providing properties such as light-harvesting, multiple light reflection and enhanced active site. Owing to the synergistic effect between g-C 3 N 4 and TiO 2 ; the light absorption region has been enhanced, leading to the improvement of photocatalytic performance. The obtained CO 2 photoreduction efficiency of HCNS@TiO 2 nanostructure is 11.3 μmol/g cat.h, which is about 5 and 10 times higher than the corresponding values for pristine g-C 3 N 4 and p-25, respectively. [ABSTRACT FROM AUTHOR]