Facile preparation of yolk–shell structured Si/SiC@C@TiO2 nanocomposites as highly efficient photocatalysts for degrading organic dye in wastewater

Abstract

The yolk–shell structured Si/SiC@C (YSSC) nanospheres were prepared by a facile magnesiothermic reduction process. After coating with TiO₂ nanoparticles, the YSSC@TiO₂ composites possess a Brunauer–Emmett–Teller (BET) and Langmuir surface area of 423 and 584 m² g⁻¹, respectively, and show high adsorption capability for methyl blue (MB) and Congo red in water. Moreover, the nanocomposites show a strong photon absorbance throughout the visible light region, and exhibit excellent photocatalytic performance for degrading MB in water. The MB degradation follows the pseudo 1st order kinetics and the calculated rate constant for YSSC@TiO₂ under UV (visible) light irradiation is approximately 4.5 (7.9), 8 (17), and 7.6 (22.7) times larger than that of the synthesized TiO₂, commercial P25 and YSSC spheres, respectively. Stability tests show that the YSSC@TiO₂ nanospheres possess high stability and maintain good photocatalytic activity over four runs of cycle experiments. The excellent photocatalytic activity of YSSC@TiO₂ can be ascribed to the synergism of high adsorption of dye molecules on the surface, extended light adsorption range and the formation of semiconductor heterostructures that allow for efficient separation of photogenerated electrons and holes through a Z-scheme system within the catalyst.