Tailored synthesis of C@TiO2 yolk–shell nanostructures for highly efficient photocatalysis

• We report the tailored synthesis of C@TiO2 yolk–shell nanostructures.
• The carbon core serves as an electron-sink to promote the exiton separation.
• The longer exiton lifetime enhances the photocatalytic performance of the catalyst.
• The yolk–shell structures have many desirable properties for photocatalysis.
• The C@TiO2 structures can be optimized to achieve high photocatalytic activity.

Composite nanostructures with well-defined characteristics are often advantageous catalysts for highly efficient photocatalytic processes. Here, we report the tailored synthesis of C@TiO2 yolk–shell nanostructures and their photocatalytic applications in the degradation of organic dyes. The conductive carbon core serves as an electron-sink to promote the separation of electron–hole pairs photo-excited in the TiO2 shell, improve their lifetime, and enhance the photocatalytic performance of the system. The yolk–shell nanostructures were synthesized through a sol–gel coating of TiO2 on resorcinol-formaldehyde (RF) resin spheres followed by silica-protected calcination and ultimately NaOH etching to remove the silica layer and produce C@TiO2 yolk–shell nanostructures. In order to improve the crystallinity of the TiO2 shell, post-processing including acid treatment and re-calcination was also carried out. The resulting yolk–shell structures have many desirable properties for photocatalytic applications including the existence of a conductive core, well-maintained structural integrity, uniform particle dimensions, favorable mesoscale porosity, tunable crystallinity, and controllable crystalline phase of TiO2. As a result, we have been able to optimize the structure and property of the composite photocatalysts and achieve superior photocatalytic performance to commercial P25-TiO2 catalysts.

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