Abstract
One of the basic challenges of CO2 photoreduction is to develop efficient photocatalysts, and the construction of heterostructure photocatalysts with intimate interfaces is an effective strategy to enhance interfacial charge transfer for realizing high photocatalytic activity. Herein, a novel UiO-66/Bi4O5Br2 heterostructure photocatalyst was constructed by depositing UiO-66 nanoparticles with octahedral morphology over the Bi4O5Br2 nanoflowers assembled from the Bi4O5Br2 nanosheets via an electrostatic self-assembly method. A tight contact interface and a built-in electric field were formed between the UiO-66 and the Bi4O5Br2, which was conducive to the photo-electrons transfer from the Bi4O5Br2 to the UiO-66 and the formation of a type-II heterojunction with highly efficient charge separation. As a result, the UiO-66/Bi4O5Br2 exhibited improved photocatalytic CO2 reduction performance with a CO generation rate of 8.35 μmol h−1 g−1 without using any sacrificial agents or noble co-catalysts. This work illustrates an applicable tactic to develop potent photocatalysts for clean energy conversion.
Highlights
The high-speed increase of carbon dioxide (CO2) concentration in the atmosphere has led to serious global warming and environmental problems (Scott and Geden, 2018; Prasad et al, 2020; Tang et al, 2020; Xu et al, 2020; Liu et al, 2021a)
Pure Bi4O5Br2 shows a series of diffraction peaks at 24.4, 27.4, 29.6, 32.6, and 46.2o, corresponding to (31-1), (212), (11-3), (020), and (422) planes of the standard monoclinic Bi4O5Br2 (PDF #37-0699); while the diffraction peaks of UiO-66 are consistent with that reported in the literature (Figure 1A) (Dong et al, 2015), indicating the successful synthesis of Bi4O5Br2 and UiO-66
Both peaks corresponding to the Bi4O5Br2 and UiO-66 are observed in Bi4O5Br2/UiO-66 hybrid, no obvious change is observed in the crystal structure after the combination of UiO-66 and Bi4O5Br2, indicating successful fabrication of the Bi4O5Br2/UiO-66 hybrid (Figure 1A)
Summary
The high-speed increase of carbon dioxide (CO2) concentration in the atmosphere has led to serious global warming and environmental problems (Scott and Geden, 2018; Prasad et al, 2020; Tang et al, 2020; Xu et al, 2020; Liu et al, 2021a). The pure UiO-66 usually demonstrates a fast recombination rate of electron holes and poor photocatalytic CO2 reduction activity (Peng et al, 2020) Some tactics, such as replacing the original ligands (Zhang et al, 2021), depositing precious metals or other co-catalysts on the surface (Zhang et al, 2020), and doping other metal elements to form new coordination bonds (Yang et al, 2017) have been investigated to ameliorate the performance of UiO-66. The BiOX with adjustable band structure seems to be a promising choice to match with UiO-66 to construct heterojunction photocatalysts for the application of CO2 reduction. The UiO-66@Bi4O5Br2 hybrid can effectively produce CO at a rate of 8.35 μmol h−1 g−1 under full-spectrum light irradiation without using any noble co-catalysts or sacrificial agents This tactic of constructing MOFs-based heterojunction provides a new way to design efficient photocatalysts with CO2 reduction activity
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