Controllable Synthesis of MIL-101(Cr)@TiO₂ Core–Shell Nanocomposites for Enhanced Photocatalytic Activity

Abstract

Incorporating high surface area and high CO 2 adsorption capacity of metal−organic frameworks (MOFs) together with highly efficient semiconductor photocatalysts provides an ideal strategy for designing CO 2 reduction photocatalysts. Controllable growth of TiO 2 nanoparticles on MIL-101(Cr) can be obtained and yields MIL-101(Cr)@TiO 2 core− shell photocatalysts via a fluoride-assisted solvothermal method. Corrosion occurs on the surface of MIL-101(Cr) by the action of F − and generates an activated surface, facilitating the growth of a TiO 2 shell. MIL-101(Cr)@TiO 2 nanocomposites with different TiO 2 contents are remarkably fabricated by controlling the reaction conditions. The morphology, structure, surface area, and composition of the as-prepared MIL-101(Cr)@TiO 2 nanocomposites are investigated by various characterization methods. The EDS mapping images reveal that the Ti and O elements are uniformly distributed on the shell, but Cr and C elements are mainly situated at the core of the composite, which further indicates the successful synthesis of the MIL-101(Cr)@TiO 2 core−shell structure. The photocatalytic conversion of CO 2 into CH 4 is noticeably enhanced by the produced MIL-101(Cr)@TiO 2 octahedra inheriting both large surface area (387.3 m 2 g −1 ) and high CO 2 adsorption capacity. Compared to pure TiO 2 nanoparticles under the same conditions, the optimized MIL-101(Cr)@TiO 2 photocatalyst exhibits a much greater CO 2 conversion efficiency, with a CH 4 generation rate of 0.22 μmol h −1 g −1 . This work will advance the experimental and theoretical basis for exploring highly efficient CO 2 reduction photocatalysts.

Fluorinated-TiO2/Mn0.2Cd0.8S S-Scheme Heterojunction with Rich Sulfur Vacancies for Photocatalytic Hydrogen Production

“…As illustrated in Figure d, the peak at 684.64 eV is identified from F 1s in the F-TiO 2 composite, which is assigned to the Ti–F species on the surface of TiO 2 . Meanwhile, as for Ti, the two peaks of F-TiO 2 at 459.05 and 464.79 eV are equivalent to Ti 2p 3/2 and Ti 2p 1/2 , respectively (Figure e). − For S, the S 2p signal peak can be divided into two characteristic peaks at 161.40 and 162.51 eV, corresponding to S 2p 3/2 and S 2p 1/2 orbital signals, respectively, indicating the existence of S 2– in the pure MCS (Figure f) . As shown in Figure g, the two characteristic peaks of Cd 3d with binding energies of 405.15 and 411.93 eV correspond to Cd 3d 5/2 and Cd 3d 3/2 , respectively.…”

Design of TiO2@Carbon@Prussian Blue Core–Shell Nanorod Arrays for Enhanced Photoelectrochemical Performance

“…Due to the considerable thickness of the PB layer, the Ti 2p peak appears weak, revealing two peaks at 458.9 and 464.7 eV, representing Ti 2p 3/2 and Ti 2p 1/2 . This observation indicates the presence of Ti in the form of Ti 4+ ions . The O 1s spectrum displays three peaks at 533.9, 531.8, and 530.1 eV, indicative of CO, C–O, and Ti–O bonds.…”

Urchin-like TiO2/CdS Nanoparticles Forming an S-scheme Heterojunction for Photocatalytic Hydrogen Production and CO2 Reduction

“…To further improve the photocatalytic ability of TiO 2 , researchers recently studied a series of new catalysts for photocatalytic H 2 and CO 2 reduction reactions, such as 3D/2D TiO 2 @Ti 3 C 2 MXene/Bi 2 S 3 , TiO 2 /C 3 N 4 , 3D ZnIn 2 S 4 /TiO 2 and so on. Of course, some scholars use the advantages of precious metals in catalysis to improve the performance of catalysts by incorporating Pt, Au, and Ag. , In addition, the performance of the TiO 2 catalyst was also improved by designing the morphology of composite materials, , Z-scheme heterojunctions, , and p–n heterojunctions . However, there are few research studies on S-scheme heterojunction catalysts constructed with cheap inorganic materials and even fewer research studies on catalysts that can photocatalyze both H 2 production and CO 2 reduction …”

“…Of course, some scholars use the advantages of precious metals in catalysis to improve the performance of catalysts by incorporating Pt, 26 Au, 27 and Ag. 28,29 In addition, the performance of the TiO 2 catalyst was also improved by designing the morphology of composite materials, 30,31 Zscheme heterojunctions, 32,33 and p−n heterojunctions. 34 However, there are few research studies on S-scheme heterojunction catalysts constructed with cheap inorganic materials and even fewer research studies on catalysts that can photocatalyze both H 2 production and CO 2 reduction.…”