Raspberry‐Like Microspheres of Core–Shell Cr ₂O ₃@TiO ₂ Nanoparticles for CO ₂ Photoreduction

Abstract

To promote the interaction of p–n semiconductors, raspberry‐like microspheres of core–shell Cr ₂O ₃@TiO ₂ nanoparticles have been fabricated through a five‐step process. Raman spectroscopy of products calcined at various temperatures reveal that the titania shell causes crystal distortion of the Cr ₂O ₃ core, without changing the microstructures of the fabricated core–shell microspheres. In situ and time‐resolved synchrotron‐based powder XRD reveals the formation of monoclinic TiO ₂ in the fourth step, but these monoclinic TiO ₂ nanocrystals undergo a phase transition when the applied calcination temperature is above 550 °C. As a result, TiO ₂(B), a magnéli phase of Ti ₄O ₇ and Cr ₂Ti ₆O ₁₅ compounds, resulting from inner doping between Cr ₂O ₃ and TiO ₂, is formed. The close interaction of Cr ₂O ₃ and TiO ₂ forms a p–n junction that decreases the recombination of photogenerated electron–hole pairs, leading to enhanced production of CH ₄ by photocatalytic reduction of CO ₂.

Abstract

Giving CO ₂ conversion the raspberry : To promote the interaction of p–n semiconductors, raspberry‐like core–shell Cr ₂O ₃@TiO ₂ nanoparticles were fabricated through a five‐step process. The products calcined at different temperatures revealed that the titania shell resulted in the crystal distortion of the Cr ₂O ₃ core, without changing the microstructures of the fabricated core–shell microspheres.