Enhanced Photocatalytic Performance of TiO₂@CeO₂ Hollow Structure through Synergetic Surface and Interface Engineering

Abstract

In this study, a synergetic structural design is developed to improve the photocatalytic performance of the sub‐micro core–shell hollow sphere (TiO2@H‐CeO2). TiO2@H‐CeO2 with maximum surface/interface effect is chosen as the substrate and then reacts with different concentrations of Ce(NO3)3·6H2O solutions. Optical properties analysis shows that after the reaction, the band gap of the composite structure and the electron–hole recombination efficiency both decrease while the photodegradation ability is effectively improved. Spectroscopic and microscopic observations reveal two changes in the structure after the reaction. The first is the deposition of CeO2 nanoparticles that can be observed inside and on the surface of the shell; the second is the doping of Ce3+ in the TiO2 nanoparticles of this shell. The deposition of CeO2 particles increases the interfacial area between the CeO2 and TiO2 and facilitates the corresponding charge transfer. The Ce3+ doping in the TiO2 shell changes the optical properties of TiO2. Therefore, the improved performance of the composite structure can be attributed to the synergy of different surfaces and interfacial effects caused by the reactions.

Heterojunction-Based Photocatalytic Degradation of Rose Bengal Dye via Gold-Decorated α-Fe2O3-CeO2 Nanocomposites under Visible-Light Irradiation

“…Additionally, the Au NPs can trap electrons and enhance the separation of electron-hole pairs, leading to the generation of more hy droxyl radicals. These radicals are responsible for degrading the dye [40,108]. Furthermore, Table S1 compares the present photocatalytic activity of α-Fe 2 O 3 -CeO 2 @Au NC with recent studies using Fe 2 O 3 -based nanoparticles under light irradiation [109][110][111][112][113][114][115][116][117][118].…”

“…These findings confirmed the formation of a heterostructure between α-Fe2O3 and CeO2. Furthermore, the deposition of Au NPs on the nanocomposite surface did not disrupt the α-Fe2O3-CeO2 nanostructure (Figure 6d), which indicates the successful integration of spherical AuNPs with the heterojunction to produce α-Fe2O3-CeO2@Au, which might hinder the recombination of e − -h + pairs and enhance their photocatalytic efficiency [40].…”

“…Additionally, the Au NPs can trap electrons and enhance the separation of electron-hole pairs, leading to the generation of more hydroxyl radicals. These radicals are responsible for degrading the dye [40,108].…”

“…Many researchers have created heterojunction composites, including α-Fe 2 O 3 @TiO 2 , α-Fe 2 O 3 @ZnO, Fe 3 O 4 -ZnO/TiO 2 , α-Fe 2 O 3 @SnO 2 , Fe 3 O 4 -CdO, and TiO 2 -CeO 2 , in an attempt to harvest solar energy, reduce the charge carrier recombination rate, and increase the photocatalytic activity [35][36][37][38][39][40]. To improve electron-hole pair separation, rare-earth oxides can be combined with α-Fe 2 O 3 [41].…”