Construction of UiO-66/Bi4O5Br2 Type-II Heterojunction to Boost Charge Transfer for Promoting Photocatalytic CO2 Reduction Performance

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.

1 Introduction

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). Investigating reliable strategies which can convert CO₂ into usable fuel can guide the healthy development of society. Among the numerous proposals for CO₂ conversion, solar photocatalysis that can efficiently convert CO₂ into useful chemical intermediates and chemical raw material (carbon monoxide, CO) has been appraised as a potential strategy that can overcome global warming as well as meet the demand for renewable fuels (Shen et al., 2019; Liu et al., 2020a). Therefore, the development of highly efficient photocatalysts plays a considerable role in the future practical application of photocatalytic CO₂ conversion (Liu, 2016; Wu et al., 2019; Wang et al., 2021a; Wang et al., 2021b).

In recent years, metal-organic framework (MOF) based semiconductors demonstrating attractive characteristics such as high surface area and a well-defined and adjustable porous structure are considered as a promising material for photocatalytic applications of organic pollutants degradation, O₂ production, H₂ production, N₂ fixation, and CO₂ reduction (Hirakawa et al., 2016; Ling et al., 2018; Dong et al., 2019; Mukhopadhyay et al., 2021; Peña-Velasco et al., 2021). Among the assorted MOF-based photocatalysts, UiO-66 is a classic Zr-based MOF material, and it has high thermal stability, unsaturated open metal sites, hygroscopic CO₂ binding sites, and superior CO₂ adsorption capacity. Therefore, UiO-66 is considered a promising candidate for application in photocatalytic CO₂ reduction (Kim et al., 2015; Wang et al., 2018a). For example, Yamani et al. prepared UiO-66-NH₂ based frameworks using a hydrothermal method and found it presented photocatalytic CO₂ reduction activity with the products of CO, CH₄, and HCOO⁻ (Zeama et al., 2020). However, the pure UiO-66 usually demonstrates a fast recombination rate of electron holes and poor photocatalytic CO₂ reduction activity (Peng et al., 2020). Recently, 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. Coupling UiO-66 with another photocatalytic semiconductor to construct a heterostructure composite can adjust the electronic transfer path and achieve high separation efficiency of photogenerated charges, which has been deemed as one of the most promising procedures to elevate the photocatalytic performance (Su et al., 2017).

Choosing a suitable semiconductor is one of the key points to construct heterojunctions with UiO-66. Among the reported semiconductors, bismuth oxyhalide BiOX (X = Cl, Br, and I) consisting of a [Bi₂O₂] layer interlaced by double layers of halogen atoms is a typical layered semiconductor, and it illustrates unique advantages of being chemically stable, non-toxic, and corrosion-resistant (Jin et al., 2019; Ren et al., 2020). It is noted that the band energy structure of BiOX can be controlled by adjusting the Bi content in bismuth oxybromide material. For instance, Ye et al. have fabricated the Bi₄O₅Br₂ nanoflowers via a bismuth-rich strategy and found that Bi₄O₅Br₂ nanoflowers with high Bi ratio owned smaller band gap and better CO₂ photoreduction activity compared to BiOBr (Ye et al., 2016). Accordingly, 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.

In this study, a novel UiO-66/Bi₄O₅Br₂ (U@B) heterojunction was fabricated via an electrical self-assembly method by wrapping the UiO-66 nanoparticles over the Bi₄O₅Br₂ nanoflowers (Scheme 1). The tight contact interface and matched energy band structure between UiO-66 and Bi₄O₅Br₂ could accelerate the charge separation to promote CO₂ reduction property. 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.

SCHEME 1

Scheme 1. Schematic depiction of preparation of U@B-X composites.

2 Experimental

2.1 Fabrication of the UiO-66/Bi₄O₅Br₂ Composite

For the preparation of pure UiO-66, 1.0 mmol ZrCl₄ (233.04 mg) and 1.0 mmol terephthalic acid (H₂BDC 166.13 mg) were dispersed into 25 ml DMF solution and sonicated for 10 min, respectively. After that, 3.6 ml acetic acid was mixed into the above solution in a 100 ml Teflon-lined autoclave and sonicated for 10 min and then heated at 120°C for 24 h. After that, the collection was centrifugated, washed, and dried overnight at 60°C to obtain the UiO-66. For the Bi₄O₅Br₂, 2 mmol KBr, and 2 mmol Bi(NO₃)₃·5H₂O were dispersed into 20 ml glycerol and stirred for 10 min, respectively. Then, the KBr solution and Bi(NO₃)₃·5H₂O solution were transferred into a 50 ml Teflon-lined autoclave and kept at 160°C for 16 h. After cooling down, the precipitate was washed and dried to obtain Bi₄O₅Br₂.

The UiO-66/Bi₄O₅Br₂ composites were prepared by an electronic assembly technique. Typically, 50 mg Bi₄O₅Br₂ with a positive zeta potential of 35.9 mV (Supplementary Figure S1) and different amounts of UiO-66 with a negative zeta potential of −20.1 mV (Supplementary Figure S1) were dispersed into 50 ml deionized water, respectively, and the above two solutions were mixed together and then sonicated for 60 min to prepare the UiO-66@Bi₄O₅Br₂ composite. The adding amount of the UiO-66@ was 5, 10, 15 mg, respectively, and the corresponding UiO-66@Bi₄O₅Br₂ samples were named U@B-5, U@B-10, and U@B-15, respectively.

2.2 Characterization Techniques

The structure, morphology, composition, and zeta potential were tested using powder X-ray diffraction (XRD, D/Max-2550, Rigaku), field emission scanning electron microscopy (FE-SEM, JXA-840A, JEOL), high-resolution transmission electron microscopy (HR-TEM, JEM-100CX II, JEOL), X-ray photoelectron spectroscopy (XPS, PHI ESCA-5000C, Perkin Elmer), and a ZS90 (Malvern Panalytical) zeta sizer, respectively. The light adsorption, Fourier transform infrared spectrum (FT-IR), Raman spectrum and transient fluorescence absorption spectroscopy were studied by the UV–vis diffuse reflectance spectra (DRS, UV2550 spectrophotometer), Nexus 870 spectrometer, DXR spectrometer, and femtosecond transient absorption spectrometer (Helios fire, Ultrafast System), respectively. The S_BET and pore size distribution of the powders were measured on an ASAP 2020 HD88 (United States). The photocurrents, electrochemical impedance spectroscopy (EIS) profiles, and Mott–Schottky plots were tested via a CHI660B electrochemical workstation.

2.3 Photocatalytic Performance Measurements

The photocatalytic CO₂ reduction experiments were measured in an enclosed quartz reactor under Xe lamp irradiation (Perfectlight, PLS-SXE300+) and the reaction temperature was controlled at 5°C by HJDC-0506 instrument to prevent thermal catalytic effects. Typically, 30 mg of U@B-X sample was dispersed in 50 ml of deionized water with no sacrificial agent by stirring for 10 min and then transformed into the enclosed quartz reactor. Then, the reaction container was filled with high purity CO₂ gas (99.995%) and the gaseous products were tested by the GC-2014C gas chromatography (GC, Shimadzu Technologies) equipped with a thermal conductivity detector (TCD) and two flame ionization detectors (FIDs) for the analysis of CO. For the stability measurement, the reactor was re-filled with CO₂ (80Kpa) and then tested under the same condition described above.

2.4 Photoelectrochemical Measurements

The photocurrents, electrochemical impedance spectroscopy (EIS) profiles, Mott–Schottky plots, and Linear sweep voltammetry (LSV) were tested via a CHI-760E electrochemical workstation.

Photocurrent measurements of samples were carried out using a three electrodes electrochemical workstation with Ag/AgCl as reference electrode, Pt wire as the counter electrode, and the catalysts as the working electrode using a 75 W 365 nm LED lamp as the light source. The working electrode was prepared with 5 mg catalysts, 250 μL ethanol, 250 μL ethylene glycol, and 40 μL Nafion solution (5 wt%) dip-coated on the FTO conducting glass. Mott-Schottky plot of UiO-66 and Bi₄O₅Br₂ were measured without light irradiation at 200 Hz, 400Hz, and 600 Hz frequencies. EIS measurements were tested in the frequency range of 1,000 kHz–0.01 Hz at 0.8 V. LSV measurements were performed by sweeping the potential from 0 to 1.2 V Na₂SO₄ aqueous solution (0.1 M, pH = ca. 7) was used as the supporting electrolyte.

3 Results and Discussions

The composition of different samples was characterized by XRD. Pure Bi₄O₅Br₂ shows a series of diffraction peaks at 24.4, 27.4, 29.6, 32.6, and 46.2^o, 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). The peak intensity of UiO-66 in the Bi₄O₅Br₂/UiO-66 hybrid increases when UiO-66 content increases. The different functional groups of the UiO-66 and the Bi₄O₅Br₂/UiO-66 hybrid were studied via FTIR technique (Figure 1B). For pure UiO-66, a series of peaks representing asymmetrical stretching of Zr-(OC) and different bending vibration modes from ligands are observed between 400 and 1,020 cm⁻¹ (Bargozideh et al., 2020). The two peaks at 1,400 and 1,580 cm⁻¹ represent the O-C-O symmetric and asymmetric tensile vibrations of the carboxyl groups of the ligands of the terephthalic acid part. The peaks at 1,500 and 1,630 cm⁻¹ are attributed to the C=C vibration mode of the H₂BDC ligands (Ahmadipouya et al., 2021). The weak peak of C=C for the Bi₄O₅Br₂ sample is caused by the adsorption of carbon impurities (glycerin) on the surface during the synthetic process. The Bi₄O₅Br₂/UiO-66 hybrids demonstrate almost the same spectra as that of pure UiO-66, indicating that the coupling UiO-66 to Bi₄O₅Br₂ would not change the functional group structure of UiO-66. In addition, Supplementary Figure S2 shows the Raman spectra of UiO-66, Bi₄O₅Br_2, and Bi₄O₅Br₂/UiO-66 composite. For the UiO-66, the peaks at 1,610, 1,440, and 1,420 cm⁻¹ correspond to the C=C stretching and coordination of Zr(IV) ions with the O-C-O symmetric stretching, respectively, while the low-frequency bands at 1,140 and 860 cm⁻¹ can be assigned to the deformation band of the benzoic acid group (Bariki et al., 2020). For the Bi₄O₅Br₂, two Raman peaks of A_1g internal and E_1g internal Bi-Br stretching modes are found at 108 and 156 cm⁻¹, respectively (Xu et al., 2021). Both Raman bands belonging to UiO-66 and Bi₄O₅Br₂ are observed in the U@B-X composites. The XRD, FTIR, and Raman results further proved the successfully synthesized of Bi₄O₅Br₂/UiO-66 hybrids.

FIGURE 1

FIGURE 1. (A) XRD patterns of UiO-66, Bi₄O₅Br₂ and U@B-X, (B) FTIR spectra of UiO-66, Bi₄O₅Br₂, and U@B-X.

The survey XPS spectra show that the Bi₄O₅Br₂/UiO-66 composite mainly contains O, C, Zr, Bi, and Br elements (Figure 2A), indicating the UiO-66 and Bi₄O₅Br₂ are successfully integrated via the self-assembly method. The high-resolution spectrum of Bi 4f of the Bi₄O₅Br₂ illustrates doublet peaks representing Bi 4f7/2 (159.1 eV) and Bi 4f5/2 (164.4 eV), respectively, implying that Bi atoms are Bi³⁺ in pure Bi₄O₅Br₂ (Figure 2B) (Ye et al., 2016). For the Bi 4f in U@B-10 composite (Figure 2B), the Bi 4f spectrum also can be divided into two peaks at 159.1 and 164.4 eV, and no difference is observed compared to the pure Bi₄O₅Br₂, indicating that Bi³⁺ can be maintained. The Br 3d spectrum of Bi₄O₅Br₂ can be divided into two peaks at 68.2 and 69.3 eV, representing Br 3d5/2 and Br 3d3/2, respectively (Figure 2C) (Bai et al., 2019). Besides, the peak position of Br 3d in U@B-10 is still located at 68.2 and 69.2 eV, respectively, revealing the same status of the Br in U@B-10 and Bi₄O₅Br₂. The O1s spectrum of UiO-66 in Figure 2D is decomposed into two peaks of Zr-O (529.6 eV) and C=O groups (531.4 eV), respectively (Cao et al., 2021). The peaks at 529.9 and 532.2 eV in Bi₄O₅Br₂ can be ascribed to the Bi-O band, while the peak of 530.9 eV stands for the surface hydroxyl groups (Chen et al., 2021; Hong et al., 2020). Figure 2E shows the spectra of Zr 3d, two strong peaks can be observed at 182.5 and 184.9 eV of UiO-66, corresponding to the Zr 3d5/2, and Zr 3d3/2, respectively (Ding et al., 2017). The XPS results evidenced the successful preparation of the Bi₄O₅Br₂/UiO-66 composite.

FIGURE 2

FIGURE 2. XPS survey spectra (A), high-resolution spectra of (B) Bi 4f, (C) O 1s, (D) Br 3d, and (E) Zr 3d for UiO-66, Bi₄O₅Br₂, and U@B-10.

The SEM image of UiO-66 is illustrated in Figure 3A, exhibiting a relatively uniform octahedral prism morphology with an average size of 200 nm. The pure Bi₄O₅Br₂ shows hierarchical and stereoscopic flower morphology, which is made up of small nanosheets (Figure 3B). For the U@B-10 hybrid, the UiO-66 octahedral prism is wrapped over the Bi₄O₅Br₂ stereoscopic flowers (Figures 3C,D). The corresponding energy-dispersive X-ray spectroscopy (EDX) element analysis (Supplementary Figure S3) displays the coexistence of Bi, Br, O, and Zr elements at the selected area of U@B-10, further proving the effective hybridization of UiO-66 and Bi₄O₅Br₂. Furthermore, an intimate interface and the crystal boundary can be observed between the UiO-66 and Bi₄O₅Br₂ (Figures 3E,F), which also proves the formation of a heterostructure. Figure 3F clearly shows the polycrystalline properties of Bi₄O₅Br₂, and the (11-3) and (310) lattice planes of Bi₄O₅Br₂ with lattice edges of 0.30 and 0.36 nm, respectively, are also observed in the U@B-10 hybrid. The Brunner−Emmet−Teller (BET) surface area of UiO-66, Bi₄O₅Br₂, and U@B-10 composite is displayed in Supplementary Table S1, and the U@B-10 composite displays a much larger BET surface area (211.12 m² g⁻¹) and pore volume (0.14 m³ g⁻¹) than that of Bi₄O₅Br₂. From the TEM images of the samples can find that part of the surface of UiO-66 was covered by Bi₄O₅Br₂ after combination, which decreased the surface area of the composite. The U@B-10 sample owns the highest average pore size (5.92 nm), which is beneficial for exposing more active sites thereby enhancing the photocatalytic activity.

FIGURE 3

FIGURE 3. FESEM images of (A) UiO-66, (B) Bi₄O₅Br₂, (C) U@B-10, (D–E) TEM of U@B-10, and (F) HRTEM of U@B-10.

The photocatalytic CO₂ reduction performances were investigated (Figures 4A,B). Pure UiO-66 and Bi₄O₅Br₂ show rather low CO₂ reduction performance. Pure UiO-66 and Bi₄O₅Br₂ present the photocatalytic CO production rate of 3.88 umolg⁻¹h⁻¹ and 5.08 umolg⁻¹ h⁻¹, respectively. Compared with pure Bi₄O₅Br₂ and UiO-66, coupling the UiO-66 octahedron on Bi₄O₅Br₂ can effectively improve the CO₂ reduction efficiency. U@B-X samples demonstrate enhanced CO₂ reduction performance: the photocatalytic CO reduction rate increases in the following order UiO-66 < Bi₄O₅Br₂ < U@B-5 < U@B-15 < U@B-10. The low CO₂ reduction of the U@B-15 may be due to the excessive deposition of UiO-66 on Bi₄O₅Br₂ impeding the light absorption of Bi₄O₅Br₂, thus inhibiting the generation of photogenerated carriers and reducing the transport of carriers. The optimal U@B-10 showed the strongest CO₂ reduction rate of 8.35 umolg⁻¹h⁻¹, which is 2.15 times of pure UiO-66 and 1.64 times of pure Bi₄O₅Br_2. It is noted that the activity of the U@B-10 is among the best reports for photocatalytic CO₂ reduction (Supplementary Table S2). The stability is an important factor in the practical application of high-efficiency photocatalyst, therefore, CO₂ reduction of U@B-10 was carried out four times under the full spectrum light (Figure 4C), and the CO production was calculated every 5 h. It can be seen that the CO production remained stable after every cycle and the crystalline structure preserved its original state (Figure 4D). All the results above indicate that the sample had excellent stability.

FIGURE 4

FIGURE 4. (A) Photocatalytic CO₂ reduction and (B) CO₂ reduction rates of different samples; (C) stability test of U@B-10 and (D) the XRD patterns of U@B-10 before and after cycles.

The charge separation behavior was investigated to explore the reason for the enhanced photocatalytic CO₂ reduction performance. Figure 5A displays that the intensity of transient photocurrent of the UiO-66 is very low, while the U@B-10 composite demonstrates the highest transient photocurrent density compared to that of the UiO-66 and Bi₄O₅Br₂, indicating that the U@B-10 composite owns the fastest separation efficiency of photogenerated carriers (Liu et al., 2020b; Liu et al., 2020c). The EIS was also used to characterize the interface charge carrier transport capacity. As shown in Figure 5B, the EIS radius of the U@B-10 composite is smaller than that of pure Bi₄O₅Br₂ and UiO-66, indicating that U@B-10 composite presents lower charge transfer resistance and higher separation rate (Liu et al., 2020d; Wang et al., 2020). Furthermore, according to the linear sweep voltammetry (LSV) analysis (Figure 5C), U@B-10 shows a lower overpotential and Tafel slope (Supplementary Figure S4) than that of pure UiO-66, indicating that the introduction of Bi₄O₅Br₂ can decrease the overpotential and promote CO₂ reduction (Liu et al., 2016; Peng et al., 2021). Time-resolved PL spectra were performed (Figure 5D). The average lifetime of U@B-10 is shorter (0.142 ns) compared with Bi₄O₅Br₂ (0.507 ns) and UiO-66 (0.460 ns), indicating that the U@B-10 heterojunction demonstrates faster transmission speed of the photogenerated carriers (Tang et al., 2019).

FIGURE 5

FIGURE 5. (A) Transient photocurrent spectra, (B) EIS spectra, (C) LSV curves, (D) TRPL of Bi₄O₅Br₂, and U@B-10.

Figure 6A reveals the UV-Vis spectra of the UiO-66, Bi₄O₅Br₂, and U@B-X composites. Due to the Zr-_OXO cluster and the charge transfer transition between the ligand and Zr (IV) (Yu et al., 2020), UiO-66 exhibits a typical absorption edge at 345 nm (Wang et al., 2016). The Bi₄O₅Br₂ demonstrates an obvious absorption edge at 440 nm. The band gap energies of UiO-66 and Bi₄O₅Br₂ are calculated to be 3.82 and 2.44 eV, respectively (Figure 6B). According to the Mott-Schottky (MS) diagram (Figure 6C), the conduction band positions of the UiO-66 and Bi₄O₅Br₂ are slated to be −0.62 and −0.82 V, respectively (Figure 6D) (Chai et al., 2018; Wei et al., 2021).

FIGURE 6

FIGURE 6. (A) UV–vis spectra, (B) Tauc plots, (C) MS plots, (D) band diagrams of UiO-66, and Bi₄O₅Br₂.

Moreover, the work function, which can reveal electron transfer in the heterostructure, was also calculated using the density functional theory (DFT) calculation (Liu et al., 2021b). Figures 7A,B shows that the work functions of Bi₄O₅Br₂ (11-3) and UiO-66 (100) are 4.09 and 4.29 eV, respectively, indicating that the Bi₄O₅Br₂ (11-3) surface Fermi levels is lower than that of UiO-66 (100) surface. Based on the Mott-Schottky curve, Bi₄O₅Br₂, and UiO-66 are n-type semiconductors, and their Fermi energy levels are close to the conduction band. Since the Fermi energy level of Bi₄O₅Br₂ is lower than that of UiO-66, the electrons of UiO-66 will transfer to Bi₄O₅Br₂ until their Fermi energy levels reach equilibrium, and a built-in electric field is formed (Wang et al., 2018b; Tao et al., 2021). Accordingly, a preliminary charge transfer mechanism of U@B-X photocatalyst is proposed (Figures 7C,D). The UiO-66 and Bi₄O₅Br₂ have a good matching band structure to form a type-II heterojunction. Based on the work functions of Bi₄O₅Br₂ (11-3) and UiO-66 (100), the electrons tend to migrate from UiO-66 to Bi₄O₅Br₂ forming an internal electric field. Driven by the internal electric field, the photogenerated electrons on the CB of Bi₄O₅Br₂ are more easily transferred to the CB of UiO-66 to participate in the CO₂ reduction reaction while the holes on the VB of UiO-66 transferred to the VB of Bi₄O₅Br₂ (Wei et al., 2018; Kuang et al., 2021).

FIGURE 7

FIGURE 7. The calculated work functions (A) (11-3) plane of Bi₄O₅Br₂ and (B) (100) plane of UiO-66; (C,D) the proposed photocatalytic mechanism of UiO-66/Bi₄O₅Br₂ composite.

4 Conclusion

In summary, a series of UiO-66@Bi₄O₅Br₂ photocatalysts were prepared via assembling UiO-66 octahedral on Bi₄O₅Br₂ nanoflower using a simple electrostatic self-assembly method. The UiO-66@Bi₄O₅Br₂ hybrids exhibited elevated photocatalytic CO₂ reduction activity under full-spectrum light illumination without any sacrificial agent, the optimal sample (U@B-10 hybrid) showed the highest CO conversion rate of 8.35 μmol h⁻¹ g⁻¹, which was 1.64 and 2.15 times higher than pure Bi₄O₅Br₂ and UiO-66, respectively. A possible mechanism of enhanced activity was supposed that UiO-66 and Bi₄O₅Br₂ demonstrated well-matched energy band structures and an intimate interface, leading to the construction of a type-II heterojunction with boosted charge separation efficiency and promoted CO₂ reduction activity. This work reports the design of photocatalysts with matched band gap structure and an intimate interface is an effective strategy to realize highly efficient CO₂ reduction.

Data Availability Statement

The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/Supplementary Material.

Author Contributions

HT and QL conceived and designed the experiments and revised the paper. DL, BZ, and LW performed most of the experiments. ZS performed the DFT calculations. The article was written through contributions of all authors. All authors have given approval to the final version of the article.

Funding

This work is sponsored by the National Natural Science Foundation of China (21975110 and 21972058) and HT also appreciates the support from the Taishan Youth Scholar Program of Shandong Province.

Conflict of Interest

The reviewer (HY) declared a past co-authorship with one of the authors (HT) to the handling Editor.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Supplementary Material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fchem.2021.804204/full#supplementary-material

References

Ahmadipouya, S., Heidarian Haris, M., Ahmadijokani, F., Jarahiyan, A., Molavi, H., Matloubi Moghaddam, F., et al. (2021). Magnetic Fe3O4@UiO-66 Nanocomposite for Rapid Adsorption of Organic Dyes from Aqueous Solution. J. Mol. Liquids 322, 114910. doi:10.1016/j.molliq.2020.114910

CrossRef Full Text | Google Scholar

Bai, Y., Yang, P., Wang, L., Yang, B., Xie, H., Zhou, Y., et al. (2019). Ultrathin Bi4O5Br2 Nanosheets for Selective Photocatalytic CO2 Conversion into CO. Chem. Eng. J. 360, 473–482. doi:10.1016/j.cej.2018.12.008

CrossRef Full Text | Google Scholar

Bargozideh, S., Tasviri, M., Shekarabi, S., and Daneshgar, H. (2020). Magnetic BiFeO3 Decorated UiO-66 as a P-N Heterojunction Photocatalyst for Simultaneous Degradation of a Binary Mixture of Anionic and Cationic Dyes. New J. Chem. 44, 13083–13092. doi:10.1039/d0nj02594a

CrossRef Full Text | Google Scholar

Bariki, R., Majhi, D., Das, K., Behera, A., and Mishra, B. G. (2020). Facile Synthesis and Photocatalytic Efficacy of UiO-66/CdIn2S4 Nanocomposites with Flowerlike 3D-Microspheres towards Aqueous Phase Decontamination of Triclosan and H2 Evolution. Appl. Catal. B: Environ. 270, 118882. doi:10.1016/j.apcatb.2020.118882

CrossRef Full Text | Google Scholar

Cao, W., Jiang, C., Chen, C., Zhou, H., and Wang, Y. (2021). A Novel Z-Scheme CdS/Bi4O5Br2 Heterostructure with Mechanism Analysis: Enhanced Photocatalytic Performance. J. Alloys Compd. 861, 158554. doi:10.1016/j.jallcom.2020.158554

CrossRef Full Text | Google Scholar

Chai, Y.-Y., Qu, D.-P., Ma, D.-K., Chen, W., and Huang, S. (2018). Carbon Quantum dots/Zn2+ Ions Doped-CdS Nanowires with Enhanced Photocatalytic Activity for Reduction of 4-nitroaniline to P-Phenylenediamine. Appl. Surf. Sci. 450, 1–8. doi:10.1016/j.apsusc.2018.04.121

CrossRef Full Text | Google Scholar

Chen, Z., Zhao, J., Chen, J., Zhang, Y., Chen, D., Wang, Q., et al. (2021). UiO-66/BiOBr Heterojunction Functionalized Cotton Fabrics as Flexible Photocatalyst for Visible-Light Driven Degradation of Dyes and Cr(VI). Sep. Purif. Technol. 258, 118007. doi:10.1016/j.seppur.2020.118007

CrossRef Full Text | Google Scholar

Ding, J., Yang, Z., He, C., Tong, X., Li, Y., Niu, X., et al. (2017). UiO-66(Zr) Coupled with Bi 2 MoO 6 as Photocatalyst for Visible-Light Promoted Dye Degradation. J. Colloid Interf. Sci. 497, 126–133. doi:10.1016/j.jcis.2017.02.060

PubMed Abstract | CrossRef Full Text | Google Scholar

Dong, D., Yan, C., Huang, J., Lu, N., Wu, P., Wang, J., et al. (2019). An Electron-Donating Strategy to Guide the Construction of MOF Photocatalysts toward Co-catalyst-free Highly Efficient Photocatalytic H2 Evolution. J. Mater. Chem. A. 7, 24180–24185. doi:10.1039/c9ta06141j

CrossRef Full Text | Google Scholar

Dong, W., Feng, C., Zhang, L., Shang, N., Gao, S., Wang, C., et al. (2015). Pd@UiO-66: An Efficient Catalyst for Suzuki-Miyaura Coupling Reaction at Mild Condition. Catal. Lett. 146, 117–125. doi:10.1007/s10562-015-1659-4

CrossRef Full Text | Google Scholar

Hirakawa, H., Shiota, S., Shiraishi, Y., Sakamoto, H., Ichikawa, S., and Hirai, T. (2016). Au Nanoparticles Supported on BiVO4: Effective Inorganic Photocatalysts for H2O2 Production from Water and O2 under Visible Light. ACS Catal. 6, 4976–4982. doi:10.1021/acscatal.6b01187

CrossRef Full Text | Google Scholar

Hong, L., Liu, F., Zang, N., Jin, W., and Yang, C. (2020). Morphology-controllable Formation of MOF-Derived C/ZrO2@1T-2H MoS2 Heterostructure for Improved Electrocatalytic Hydrogen Evolution. Int. J. Hydrogen Energ. 45, 14831–14840. doi:10.1016/j.ijhydene.2020.03.184

CrossRef Full Text | Google Scholar

Jin, X., Lv, C., Zhou, X., Xie, H., Sun, S., Liu, Y., et al. (2019). A Bismuth Rich Hollow Bi4O5Br2 Photocatalyst Enables Dramatic CO2 Reduction Activity. Nano Energy 64, 103955. doi:10.1016/j.nanoen.2019.103955

CrossRef Full Text | Google Scholar

Kim, S.-N., Lee, Y.-R., Hong, S.-H., Jang, M.-S., and Ahn, W.-S. (2015). Pilot-scale Synthesis of a Zirconium-Benzenedicarboxylate UiO-66 for CO2 Adsorption and Catalysis. Catal. Today 245, 54–60. doi:10.1016/j.cattod.2014.05.041

CrossRef Full Text | Google Scholar

Kuang, P., Wang, Y., Zhu, B., Xia, F., Tung, C. W., Wu, J., et al. (2021). Pt Single Atoms Supported on N‐Doped Mesoporous Hollow Carbon Spheres with Enhanced Electrocatalytic H 2 ‐Evolution Activity. Adv. Mater. 33, 2008599. doi:10.1002/adma.202008599

CrossRef Full Text | Google Scholar

Ling, C., Niu, X., Li, Q., Du, A., and Wang, J. (2018). Metal-Free Single Atom Catalyst for N2 Fixation Driven by Visible Light. J. Am. Chem. Soc. 140, 14161–14168. doi:10.1021/jacs.8b07472

PubMed Abstract | CrossRef Full Text | Google Scholar

Liu, L. (2016). Controllable ZnO Nanorod Arrays@carbon Fibers Composites: Towards Advanced CO2 Photocatalytic Reduction Catalysts. Ceramics Int. 42, 12516–12520. doi:10.1016/j.ceramint.2016.04.136

CrossRef Full Text | Google Scholar

Liu, Q., He, X., Peng, J., Yu, X., Tang, H., and Zhang, J. (2021). Hot-electron-assisted S-Scheme Heterojunction of Tungsten Oxide/graphitic Carbon Nitride for Broad-Spectrum Photocatalytic H2 Generation. Chin. J. Catal. 42, 1478–1487. doi:10.1016/s1872-2067(20)63753-6

CrossRef Full Text | Google Scholar

Liu, Q., He, X., Tao, J., Tang, H., and Liu, Z. Q. (2020). Oxygen Vacancies Induced Plasmonic Effect for Realizing Broad‐Spectrum‐Driven Photocatalytic H 2 Evolution over an S‐Scheme CdS/W 18 O 49 Heterojunction. ChemNanoMat 7, 44–49. doi:10.1002/cnma.202000536

CrossRef Full Text | Google Scholar

Liu, Q., Huang, J., Tang, H., Yu, X., and Shen, J. (2020). Construction 0D TiO2 nanoparticles/2D CoP Nanosheets Heterojunctions for Enhanced Photocatalytic H2 Evolution Activity. J. Mater. Sci. Technol. 56, 196–205. doi:10.1016/j.jmst.2020.04.026

CrossRef Full Text | Google Scholar

Liu, Q., Huang, J., Wang, L., Yu, X., Sun, J., and Tang, H. (2020). Unraveling the Roles of Hot Electrons and Cocatalyst toward Broad Spectrum Photocatalytic H 2 Generation of g‐C 3 N 4 Nanotube. Sol. RRL 5, 2000504. doi:10.1002/solr.202000504

CrossRef Full Text | Google Scholar

Liu, X., Zhao, Y., Yang, X., Liu, Q., Yu, X., Li, Y., et al. (2020). Porous Ni5P4 as a Promising Cocatalyst for Boosting the Photocatalytic Hydrogen Evolution Reaction Performance. Appl. Catal. B: Environ. 275, 119144. doi:10.1016/j.apcatb.2020.119144

CrossRef Full Text | Google Scholar

Liu, Y., Li, L., Li, Q., Lin, J., Guo, Z., Zhang, X., et al. (2021). Fluorine Doped Porous boron Nitride for Efficient CO2 Capture and Separation: A DFT Study. Appl. Surf. Sci. 556, 149775. doi:10.1016/j.apsusc.2021.149775

CrossRef Full Text | Google Scholar

Liu, Z. Q., Cheng, H., Li, N., Ma, T. Y., and Su, Y. Z. (2016). ZnCo 2 O 4 Quantum Dots Anchored on Nitrogen‐Doped Carbon Nanotubes as Reversible Oxygen Reduction/Evolution Electrocatalysts. Adv. Mater. 28 (19), 3777–3784. doi:10.1002/adma.201506197

PubMed Abstract | CrossRef Full Text | Google Scholar

Mukhopadhyay, S., Shimoni, R., Liberman, I., Ifraemov, R., Rozenberg, I., and Hod, I. (2021). Assembly of a Metal-Organic Framework (MOF) Membrane on a Solid Electrocatalyst: Introducing Molecular‐Level Control over Heterogeneous CO 2 Reduction. Angew. Chem. Int. Ed. 60, 13423–13429. doi:10.1002/anie.202102320

CrossRef Full Text | Google Scholar

Peña-Velasco, G., Hinojosa-Reyes, L., Morán-Quintanilla, G. A., Hernández-Ramírez, A., Villanueva-Rodríguez, M., and Guzmán-Mar, J. L. (2021). Synthesis of Heterostructured Catalyst Coupling MOF Derived Fe₂O₃ with TiO₂ for Enhanced Photocatalytic Activity in Anti-inflammatory Drugs Mixture Degradation. Ceram. Int. 47, 24632–24640. doi:10.1016/j.ceramint.2021.05.185

CrossRef Full Text | Google Scholar

Peng, J., Shen, J., Yu, X., Tang, H., and Liu, Q. (2021). Construction of LSPR-Enhanced 0D/2D CdS/MoO3− S-Scheme Heterojunctions for Visible-Light-Driven Photocatalytic H2 Evolution. Chin. J. Catal. 42, 87–96. doi:10.1016/s1872-2067(20)63595-1

CrossRef Full Text | Google Scholar

Peng, X., Ye, L., Ding, Y., Yi, L., Zhang, C., and Wen, Z. (2020). Nanohybrid Photocatalysts with ZnIn2S4 Nanosheets Encapsulated UiO-66 Octahedral Nanoparticles for Visible-Light-Driven Hydrogen Generation. Appl. Catal. B: Environ. 260, 118152. doi:10.1016/j.apcatb.2019.118152

CrossRef Full Text | Google Scholar

Prasad, C., Tang, H., Liu, Q., Bahadur, I., Karlapudi, S., and Jiang, Y. (2020). A Latest Overview on Photocatalytic Application of G-C3n4 Based Nanostructured Materials for Hydrogen Production. Int. J. Hydrogen Energ. 45, 337–379. doi:10.1016/j.ijhydene.2019.07.070

CrossRef Full Text | Google Scholar

Ren, X., Gao, M., Zhang, Y., Zhang, Z., Cao, X., Wang, B., et al. (2020). Photocatalytic Reduction of CO2 on BiOX: Effect of Halogen Element Type and Surface Oxygen Vacancy Mediated Mechanism. Appl. Catal. B: Environ. 274, 119063. doi:10.1016/j.apcatb.2020.119063

CrossRef Full Text | Google Scholar

Scott, V., and Geden, O. (2018). The challenge of Carbon Dioxide Removal for EU Policy-Making. Nat. Energ. 3, 350–352. doi:10.1038/s41560-018-0124-1

CrossRef Full Text | Google Scholar

Shen, J., Shen, J., Zhang, W., Yu, X., Tang, H., Zhang, M., et al. (2019). Built-in Electric Field Induced CeO2/Ti3C2-MXene Schottky-junction for Coupled Photocatalytic Tetracycline Degradation and CO2 Reduction. Ceramics Int. 45, 24146–24153. doi:10.1016/j.ceramint.2019.08.123

CrossRef Full Text | Google Scholar

Su, Y., Zhang, Z., Liu, H., and Wang, Y. (2017). Cd0.2Zn0.8S@UiO-66-NH2 Nanocomposites as Efficient and Stable Visible-Light-Driven Photocatalyst for H2 Evolution and CO2 Reduction. Appl. Catal. B: Environ. 200, 448–457. doi:10.1016/j.apcatb.2016.07.032

CrossRef Full Text | Google Scholar

Tang, H., Wang, R., Zhao, C., Chen, Z., Yang, X., Bukhvalov, D., et al. (2019). Oxamide-modified G-C3n4 Nanostructures: Tailoring Surface Topography for High-Performance Visible Light Photocatalysis. Chem. Eng. J. 374, 1064–1075. doi:10.1016/j.cej.2019.06.029

CrossRef Full Text | Google Scholar

Tang, H., Xia, Z., Chen, R., Liu, Q., and Zhou, T. (2020). Oxygen Doped g‐C 3 N 4 with Nitrogen Vacancy for Enhanced Photocatalytic Hydrogen Evolution. Chem. Asian J. 15, 3456–3461. doi:10.1002/asia.202000912

PubMed Abstract | CrossRef Full Text | Google Scholar

Tao, J., Yu, X., Liu, Q., Liu, G., and Tang, H. (2021). Internal Electric Field Induced S-Scheme Heterojunction MoS2/CoAl LDH for Enhanced Photocatalytic Hydrogen Evolution. J. Colloid Interf. Sci. 585, 470–479. doi:10.1016/j.jcis.2020.10.028

CrossRef Full Text | Google Scholar

Wang, A., Zhou, Y., Wang, Z., Chen, M., Sun, L., and Liu, X. (2016). Titanium Incorporated with UiO-66(Zr)-type Metal-Organic Framework (MOF) for Photocatalytic Application. RSC Adv. 6, 3671–3679. doi:10.1039/c5ra24135a

CrossRef Full Text | Google Scholar

Wang, J., Chen, J., Wang, P., Hou, J., Wang, C., and Ao, Y. (2018). Robust Photocatalytic Hydrogen Evolution over Amorphous Ruthenium Phosphide Quantum Dots Modified G-C3n4 Nanosheet. Appl. Catal. B: Environ. 239, 578–585. doi:10.1016/j.apcatb.2018.08.048

CrossRef Full Text | Google Scholar

Wang, L., Tan, H., Zhang, L., Cheng, B., and Yu, J. (2021). In-situ Growth of Few-Layer Graphene on ZnO with Intimate Interfacial Contact for Enhanced Photocatalytic CO2 Reduction Activity. Chem. Eng. J. 411, 128501. doi:10.1016/j.cej.2021.128501

CrossRef Full Text | Google Scholar

Wang, R., Shen, J., Zhang, W., Liu, Q., Zhang, M., Zulfiqar, , et al. (2020). Build-in Electric Field Induced Step-Scheme TiO2/W18O49 Heterojunction for Enhanced Photocatalytic Activity under Visible-Light Irradiation. Ceramics Int. 46, 23–30. doi:10.1016/j.ceramint.2019.08.226

CrossRef Full Text | Google Scholar

Wang, Y., Du, R., Li, Z., Song, H., Chao, Z., Zu, D., et al. (2021). Rationally Designed CdS/Ti3C2 MXene Electrocatalysts for Efficient CO2 Reduction in Aqueous Electrolyte. Ceramics Int. 47, 28321–28327. doi:10.1016/j.ceramint.2021.06.249

CrossRef Full Text | Google Scholar

Wang, Y., Hu, Z., Kundu, T., Cheng, Y., Dong, J., Qian, Y., et al. (2018). Metal-Organic Frameworks with Reduced Hydrophilicity for Postcombustion CO2 Capture from Wet Flue Gas. ACS Sustain. Chem. Eng. 6, 11904–11912. doi:10.1021/acssuschemeng.8b02173

CrossRef Full Text | Google Scholar

Wei, R.-B., Huang, Z.-L., Gu, G.-H., Wang, Z., Zeng, L., Chen, Y., et al. (2018). Dual-cocatalysts Decorated Rimous CdS Spheres Advancing Highly-Efficient Visible-Light Photocatalytic Hydrogen Production. Appl. Catal. B: Environ. 231, 101–107. doi:10.1016/j.apcatb.2018.03.014

CrossRef Full Text | Google Scholar

Wei, S., Heng, Q., Wu, Y., Chen, W., Li, X., and Shangguan, W. (2021). Improved Photocatalytic CO2 Conversion Efficiency on Ag Loaded Porous Ta2O5. Appl. Surf. Sci. 563, 150273. doi:10.1016/j.apsusc.2021.150273

CrossRef Full Text | Google Scholar

Wu, Y. A., McNulty, I., Liu, C., Lau, K. C., Liu, Q., Paulikas, A. P., et al. (2019). Facet-dependent Active Sites of a Single Cu2O Particle Photocatalyst for CO2 Reduction to Methanol. Nat. Energ. 4, 957–968. doi:10.1038/s41560-019-0490-3

CrossRef Full Text | Google Scholar

Xu, M., Wang, Y., Ha, E., Zhang, H., and Li, C. (2021). Reduced Graphene oxide/Bi4O5Br2 Nanocomposite with Synergetic Effects on Improving Adsorption and Photocatalytic Activity for the Degradation of Antibiotics. Chemosphere 265, 129013. doi:10.1016/j.chemosphere.2020.129013

PubMed Abstract | CrossRef Full Text | Google Scholar

Xu, Q., Zhang, L., Cheng, B., Fan, J., and Yu, J. (2020). S-scheme Heterojunction Photocatalyst. Chem 6, 1543–1559. doi:10.1016/j.chempr.2020.06.010

CrossRef Full Text | Google Scholar

Yang, Z., Xu, X., Liang, X., Lei, C., Gao, L., Hao, R., et al. (2017). Fabrication of Ce Doped UiO-66/graphene Nanocomposites with Enhanced Visible Light Driven Photoactivity for Reduction of Nitroaromatic Compounds. Appl. Surf. Sci. 420, 276–285. doi:10.1016/j.apsusc.2017.05.158

CrossRef Full Text | Google Scholar

Ye, L., Jin, X., Liu, C., Ding, C., Xie, H., Chu, K. H., et al. (2016). Thickness-ultrathin and Bismuth-Rich Strategies for BiOBr to Enhance Photoreduction of CO 2 into Solar Fuels. Appl. Catal. B: Environ. 187, 281–290. doi:10.1016/j.apcatb.2016.01.044

CrossRef Full Text | Google Scholar

Yu, H., Ma, H., Wu, X., Wang, X., Fan, J., and Yu, J. (2020). One‐Step Realization of Crystallization and Cyano‐Group Generation for g‐C 3 N 4 Photocatalysts with Improved H 2 Production. Sol. RRL 5, 2000372. doi:10.1002/solr.202000372

CrossRef Full Text | Google Scholar

Zeama, M., Morsy, M., Abdel-Azeim, S., Abdelnaby, M., Alloush, A., and Yamani, Z. (2020). Photophysical and Photocatalytic Properties of Structurally Modified UiO-66. Inorg. Chim. Acta 501, 119287. doi:10.1016/j.ica.2019.119287

CrossRef Full Text | Google Scholar

Zhang, X., Fan, Y., You, E., Li, Z., Dong, Y., Chen, L., et al. (2021). MOF Encapsulated Sub-nm Pd skin/Au Nanoparticles as Antenna-Reactor Plasmonic Catalyst for Light Driven CO2 Hydrogenation. Nano Energy 84, 105950. doi:10.1016/j.nanoen.2021.105950

CrossRef Full Text | Google Scholar

Zhang, X., Song, L., Bi, F., Zhang, D., Wang, Y., and Cui, L. (2020). Catalytic Oxidation of Toluene Using a Facile Synthesized Ag Nanoparticle Supported on UiO-66 Derivative. J. Colloid Interf. Sci. 571, 38–47. doi:10.1016/j.jcis.2020.03.031

CrossRef Full Text | Google Scholar