Preparation and photocatalytic properties CuS-Bi2WO6/carbon nanofibers composites
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摘要: 铬是一种常见的重金属污染物，广泛用于各种工业过程。采用溶剂热法制备了不同CNFs(活性纳米碳纤维)含量的CuS-Bi2WO6/CNFs复合光催化剂，改善可见光照射下六价铬的还原。通过XRD、SEM、TEM、FTIR、XPS、UV-Vis、PL和光电流等技术对样品的晶型、形貌、结构、元素组成、表面官能团、光学性质等进行了测试与表征，并考察了CuS-Bi2WO6/CNFs光催化还原Cr(VI)的活性。结果表明，CuS-Bi2WO6/CNFs复合材料的光催化活性明显高于CuS、Bi2WO6和CuS-Bi2WO6。在可见光照射下，1%CuS-Bi2WO6/CNFs对Cr(VI)还原表现出优异的光催化活性，在3 h内还原率为98%。1%CuS-Bi2WO6/CNFs复合材料在4次循环后也表现出良好的稳定性和可回收性。此外，活性基团捕获实验表明，羟基自由基(•OH)、光生空穴(h+)和超氧自由基(•O2−)参与了CuS-Bi2WO6/CNFs对Cr(VI)的还原，而•O2−是该体系的主要活性组分，并在此基础上初步探讨了光催化反应机制。本文的研究结果表明，通过简单可控的溶剂热法，可以实现CuS-Bi2WO6/CNFs的制备，并且证实了CuS-Bi2WO6/CNFs复合材料在六价铬处理方面的良好前景。Abstract: Chromium is a common heavy metal pollutant and extensively used in variety of industrial processes. CuS-Bi2WO6/CNFs (carbon nanofibers) composite photocatalysts with different CNFs content were prepared by solvothermal method to remove Cr(VI) from the aqueous solution. The crystal form, morphology, structure, elemental composition, surface functional groups and optical properties of the samples were characterized by XRD, SEM, TEM, FTIR, XPS, UV-Vis and PL. The photocatalytic degradation of Cr(VI) by CuS-Bi2WO6/CNFs composite materials was evaluated. The results show that the photocatalytic activity of the CuS-Bi2WO6/CNFs composite is obviously higher than that of the CuS、Bi2WO6 and CuS/Bi2WO6. Under visible light irradiation, 1%CuS-Bi2WO6/CNFs composites show higher photocatalytic degradation performance, and the reduction rate of Cr(VI) is 98% within 3 h. And 1%CuS-Bi2WO6/CNFs composites also show strong stability and recoverability after four cycles. In addition, the experimental results of active group capture show that hydroxyl radical (•OH), photogenerated hole (h+) and superoxide radical (•O2−) are involved in the reduction of Cr(VI) on CuS-Bi2WO6/CNFs, and •O2− is the main active components of the system. The photocatalytic reaction mechanism was discussed. The research results show that the preparation of CuS-Bi2WO6/CNFs can be achieved by a simple and controllable solvothermal method, and it has confirmed the good prospects of CuS-Bi2WO6/CNFs composites in the treatment of hexavalent chromium.
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Key words:
- photocatalytic /
- composite photocatalyst /
- Cr(VI) /
- reduction /
- carbon nanofibers /
- CuS /
- Bi2WO6
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图 1 不同活性纳米碳纤维(CNFs)含量的CuS-Bi2WO6/CNFs光催化材料的XRD图谱
Figure 1. XRD patterns of CuS-Bi2WO6/carbon nanofibers (CNFs) photocatalysts with different CNFs content
图 2 不同CNFs含量的CuS-Bi2WO6/CNFs光催化材料的FTIR图谱
Figure 2. FTIR spectra of CuS-Bi2WO6/CNFs photocatalysts with different CNFs content
图 3 Bi2WO6 (a)、5%CuS-Bi2WO6 (b)、1%CuS-Bi2WO6/CNFs (c) 光催化剂的SEM图像，5%CuS-Bi2WO6 (d)、1%CuS-Bi2WO6/CNFs(20 nm) (e)和1%CuS-Bi2WO6/CNFs(10 nm) (f) 的TEM图像
Figure 3. SEM images of Bi2WO6 (a), 5%CuS-Bi2WO6 (b), 1%CuS-Bi2WO6/CNFs (c) and TEM images of 5%CuS-Bi2WO6 (d), 1%CuS-Bi2WO6/CNFs (20 nm) (e) and 1%CuS-Bi2WO6/CNFs (10 nm) (f)
图 4 1%CuS-Bi2WO6/CNFs的XPS图谱：(a)全谱；(b) Bi4f；(c) W4f；(d) Cu2p；(e) C1s；(f) S2p
Figure 4. XPS spectra of 1%CuS-Bi2WO6/CNFs: (a) Full spectrum; (b) Bi4f; (c) W4f; (d) Cu2p; (e) C1s; (f) S2p
图 5 不同CNFs含量的CuS-Bi2WO6/CNFs光催化材料的紫外-可见光吸收光谱
Figure 5. UV-Vis spectra of CuS-Bi2WO6/CNFs photocatalysts with different CNFs content
图 6 Bi2WO6和CuS-Bi2WO6/CNFs的带隙能谱图
Figure 6. Band gap spectrum of Bi2WO6 and CuS-Bi2WO6/CNFs
Eg—Semiconductor band gap width; α—Absorptivity
图 7 Bi2WO6、CuS-Bi2WO6和1%CuS-Bi2WO6/CNFs光催化剂的荧光光谱图
Figure 7. PL spectra of photocatalysts Bi2WO6, CuS-Bi2WO6 and 1%CuS-Bi2WO6/CNFs
图 8 Bi2WO6和1%CuS-Bi2WO6/CNFs光催化剂的态光电流响应图
Figure 8. Transient photocurrent responses spectra of photocatalysts Bi2WO6 and 1%CuS-Bi2WO6/CNFs
图 9 不同CNFs含量的CuS-Bi2WO6/CNFs光催化材料的吸附曲线
Figure 9. Material adsorption curve of CuS-Bi2WO6/CNFs photocatalysts with different CNFs contents
图 10 不同CNFs含量的CuS-Bi2WO6/CNFs光催化材料的Cr(VI)还原曲线
Figure 10. Cr (VI) reduction original curve line of CuS-Bi2WO6/CNFs photocatalysts with different CNFs contents
图 11 不同CNFs含量的CuS-Bi2WO6/CNFs光催化材料一级反应动力学曲线
Figure 11. First order reaction kinetic curve of CuS-Bi2WO6/CNFs photocatalysts with different CNFs contents
C0—Initial concentration of solution; Ct—Concentration of solution at time t
图 12 1%CuS-Bi2WO6/CNFs降解Cr(VI)稳定性测试
Figure 12. Cyclic photocatalytic of 1%CuS-Bi2WO6/CNFs reduction of Cr(VI) curve
图 13 1%CuS-Bi2WO6/CNFs反应前后XRD图谱
Figure 13. XRD patterns before and after reaction of 1%CuS-Bi2WO6/CNFs
图 14 CuS-Bi2WO6/CNFs对Cr(VI)的光催化还原活性物质捕捉实验
Figure 14. Active substance capture experiment with CuS-Bi2WO6/CNFs to reduction of Cr(VI)
IPA—Isopropanol; BQ—Benzoquinone; EDTA—Ethylene diamine tetraacetic acid
图 15 1% CuS-Bi2WO6/CNFs的DMPO–·O2−自旋捕获光谱
Figure 15. DMPO–·O2− spin-trapping spectra of 1% CuS-Bi2WO6/CNFs
图 16 CuS-Bi2WO6/CNFs光催化还原Cr(VI)机制图
Figure 16. CuS-Bi2WO6/CNFs photocatalytic reduction of Cr(VI) mechanism diagram
CB—Conduction band; VB—Valence band
表 1 CuS-Bi2WO6/CNFs复合材料的命名
Table 1. Naming of CuS-Bi2WO6/CNFs composite
Specimen Mass ratio of CNFs∶
CuS-Bi2WO6/%0.5%CuS-Bi2WO6/CNFs 0.5 1%CuS-Bi2WO6/CNFs 1 2%CuS-Bi2WO6/CNFs 2 4%CuS-Bi2WO6/CNFs 4 6%CuS-Bi2WO6/CNFs 6 
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