Effect of MoS2 loading on the photocatalytic performance of MoS2/TiO2 nanocomposites in phenol degradation and the corresponding reaction mechanism analysis
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摘要: 通过水解法制备TiO2纳米颗粒,与经过超声处理后的MoS2片层纳米材料复合制备MoS2/TiO2纳米催化剂,考察不同MoS2负载量对其光催化降解苯酚效率及路径的影响。XRD、SEM、EDS、FT-IR和UV-vis DRS等表征结果表明,复合催化剂主要由锐钛矿型TiO2和MoS2组成;剥离后的MoS2呈现薄片层状结构,均匀地分散在TiO2纳米颗粒当中。光催化降解苯酚性能测试结果显示,对于MoS2/TiO2催化剂,MoS2负载量的提高有利于光催化降解苯酚效率的提高;当MoS2负载量为27%时,复合MoS2/TiO2纳米颗粒的光催化性能最佳,反应80 min后可将苯酚完全降解。通过对苯酚降解过程中生成中间产物跟踪发现,MoS2负载量的提高有利于促进中间产物苯醌、对苯二酚以及邻苯二酚的生成,进而提升了MoS2/TiO2复合材料的光催化性能。Abstract: MoS2/TiO2 nanocomposites was prepared by mixing MoS2 with hydrothermally synthesized TiO2; the effects of MoS2 loading on the photocatalytic performance of MoS2/TiO2 in phenol degradation were investigated. The XRD, SEM, EDS, FT-IR and UV-vis DRS characterization results show that for the MoS2/TiO2 nanocomposites, lamellar MoS2 is uniformly dispersed around the TiO2 nanoparticles. The increase of MoS2 loading is beneficial to the photocatalytic degradation of phenol; with a MoS2 loading of 27%, the MoS2/TiO2 nanoparticles exhibited the highest photocatalytic activity, over which phenol can be completely degraded in 80 min. The intermediates during reaction are further tracked to investigate the reaction kinetics of photodegradation of phenol over MoS2/TiO2 nanocomposties. The results reveal that an increase in MoS2 loading is able to promote the formation of various intermediates such as benzoquinone, hydroquinone and catechol, which can further enhance the overall photodegradation efficiency.
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Key words:
- MoS2/TiO2 /
- photocatalysis /
- phenol /
- intermediates /
- degradation mechanism
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表 1 复合催化剂的EDS元素分析
Table 1 Results of EDS spectra of MoS2/TiO2
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[1] AHMED S, RASUL M G, MARTENS W N, BROWN R, HASHIB M A. Heterogeneous photocatalytic degradation of phenols in wastewater: a review on current status and developments[J]. Desalination, 2010, 261(1): 3-18. https://www.researchgate.net/publication/223424283_Heterogeneous_Photocatalytic_Degradation_of_Phenols_in_Wastewater_A_Review_on_Current_Status_and_Developments [2] GAO F, WANG Y, SHI D, ZHANG J, WANG M, JING X, HUMPHRY-Baker R, WANG P, ZAKEERUDDIN SM, GRÄTZEL M. Enhance the optical absorptivity of nanocrystalline TiO2 film with high molar extinction coefficient ruthenium sensitizers for high performance dye-sensitized solar cells[J]. J Am Chem Soc, 2008, 130(32): 10720-10728. doi: 10.1021/ja801942j [3] 王广建, 李佳佳, 吴春泽, 王芳. TiO2-Al2O3复合载体的制备及Co-Mo/TiO2-Al2O3催化剂加氢脱硫性能的研究[J].燃料化学学报, 2016, 44(12): 1518-1522. doi: 10.3969/j.issn.0253-2409.2016.12.016WANG Guang-jian, LI Jia-jia, WU Chun-ze, WANG Fang. Study on the preparation of TiO2-Al2O3 composite support and its application in Co-Mo/TiO2-Al2O3 catalyst for hydro-desulfurization[J]. J Fuel Chem Technol, 2016, 44(12): 1518-1522. doi: 10.3969/j.issn.0253-2409.2016.12.016 [4] RIYAPAN S, ZHANG Y, WONGKAEW A, PONGTHAWORNSAKUN B, MONNIER J. R, PANPRANOT. Preparation of improved Ag-Pd/TiO2 catalysts using the combined strong electrostatic adsorption and electroless deposition methods for the selective hydrogenation of acetylene[J]. Catal Sci Technol, 2016, 6(14): 5608-5617. http://pubs.rsc.org/en/content/articlepdf/2016/cy/c6cy00121a [5] FEI J, LI J. Controlled preparation of porous TiO2-Ag nanostructures through supramolecular assembly for plasmon-enhanced photocatalysis[J]. Adv Mater, 2015, 27(2): 314-319. doi: 10.1002/adma.v27.2 [6] WANG P, YAP P S, LIM T T. C-N-S tridoped TiO2 for photocatalytic degradation of tetracycline under visible-light irradiation[J]. Appl Catal A: Gen, 2011, 399(1): 252-261. https://www.researchgate.net/publication/232404312_C-N-S_tridoped_TiO2_for_photocatalytic_degradation_of_tetracycline_under_visible-light_irradiation [7] 郝瑞鹏, 杨朋举, 王志坚, 朱珍平.贵金属负载TiO2对光催化还原CO2选择性的影响[J].燃料化学学报, 2015, 43(1):94-99. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract18561.shtmlHAO Rui-peng, YANG Peng-ju, WANG Zhi-jian, ZHU Zhen-ping. Effect of noble metals loaded TiO2 on the selectivity of photocatalytic CO2 reduction[J]. J Fuel Chem Technol, 2015, 43(1): 94-99. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract18561.shtml [8] WEI X, SHAO C, LI X, LU N, WANG K, ZHANG Z, LIU Y. Facile in situ synthesis of plasmonicnanoparticles-decorated g-C3N4/TiO2 heterojunction nanofibers and comparison study of their photosynergistic effects for efficient photocatalytic H2 evolution[J]. Nanoscale, 2016, 8(21): 11034-11043. doi: 10.1039/C6NR01491G [9] KAYACI F, VEMPATI S, OZGIT Akgun C, DONMEZ I, BIYIKLI N, UYAR T. Selective isolation of the electron or hole in photocatalysis: ZnO-TiO2 and TiO2-ZnO core-shell structured heterojunction nanofibers via electrospinning and atomic layer deposition[J]. Nanoscale, 2014, 6(11): 5735-5745. doi: 10.1039/c3nr06665g [10] ZHENG L, HAN S, LIU H, YU P, FANG X. Hierarchical MoS2 Nanosheet@TiO2 Nanotube Array Composites with Enhanced Photocatalytic and Photocurrent Performances[J]. Small, 2016, 12(11): 1527-1536. doi: 10.1002/smll.v12.11 [11] XIE J, ZHANG H, LI S, WANG R, SUN X, ZHOU M. Defect-rich MoS2 ultrathin nanosheets with additional active edge sites for enhanced electrocatalytic hydrogen evolution[J]. Adv Mater, 2013, 25(40): 5807-5813. doi: 10.1002/adma.v25.40 [12] YOON Y, GANAPATHI K, SALAHUDDIN S. How good can monolayer MoS2 transistors be?[J]. Nano Lett, 2011, 11(9): 3768-3773. doi: 10.1021/nl2018178 [13] BANG G S, NAM K W, KIM J Y, SHIN J, CHOU J W, CHOI S Y. Effective liquid-phase exfoliation and sodium ion battery application of MoS2 nanosheets[J]. Acs Appl Mater Inter, 2014, 6(10): 7084-7089. doi: 10.1021/am4060222 [14] ZHOU K G, MAO N N, WANG H X, PENG Y, ZHANG H L. A Mixed-Solvent Strategy for Efficient Exfoliation of Inorganic Graphene Analogues[J]. Angew Chem Int Edit, 2011, 123(46): 11031-11034. doi: 10.1002/ange.v123.46 [15] MA J, TAN X, YU T, LI X. Fabrication of g-C3N4/TiO2 hierarchical spheres with reactive {001} TiO2 crystal facets and its visible-light photocatalytic activity[J]. Int J Hydrogen Energ, 2016, 41(6): 3877-3887. doi: 10.1016/j.ijhydene.2015.12.191 [16] WANG C, ZHU W, XU Y, XU H, ZHANG M, CHAO Y, YIN S, LI H, WANG J. Preparation of TiO2/g-C3N4 composites and their application in photocatalytic oxidative desulfurization[J]. Ceram Int, 2014, 40(8): 11627-11635. doi: 10.1016/j.ceramint.2014.03.156 [17] TOBILE K. Symmetric pseudocapacitors based on molybdenum disulfide (MoS2)-modified carbon nanospheres: correlating physicochemistry and synergistic interaction on energy storage[J]. J Mater Chem A, 2016, 4: 6411-6425. doi: 10.1039/C6TA00114A [18] LI J G, ISHIGAKI T, SUN X. Anatase, brookite, and rutile nanocrystals via redox reactions under mild hydrothermal conditions: phase-selective synthesis and physicochemical properties[J]. J Phys Chem C, 2007, 111(13): 4969-4976. doi: 10.1021/jp0673258 [19] ZHU Y, LING Q, LIU Y, WANG H, ZHU Y. Photocatalytic H2 evolution on MoS2-TiO2 catalysts synthesized via mechanochemistry[J]. Phys Chem Chem Phys, 2015, 17(2): 933-940. doi: 10.1039/C4CP04628E [20] 吴思展. 类石墨氮化碳(g-C3N4)的合成、加工处理、修饰及其光催化性能的研究[D]. 华南理工大学, 2014. http://cdmd.cnki.com.cn/Article/CDMD-10561-1015020894.htmWU Si-zhan. Synthesis, Processing and modification of graphitic carbon nitride with enhanced photocatalytic activity[D]. South China University Technol, 2014. http://cdmd.cnki.com.cn/Article/CDMD-10561-1015020894.htm [21] WANG X, SØ L, REN S, WENDT S, HALD P, MAMAKHEL A. The influence of crystallite size and crystallinity of anatase nanoparticles on the photo-degradation of phenol[J]. J Catal, 2014, 310: 100-108. doi: 10.1016/j.jcat.2013.04.022 [22] CHEN B, LIU E, HE F, SHI C, HE C, LI J. 2D sandwich-like carbon-coated ultrathin TiO2@defect-rich MoS2 hybrid nanosheets: Synergistic-effect-promoted electrochemical performance for lithium ion batteries[J]. Nano Energy, 2016, 26: 541-549. doi: 10.1016/j.nanoen.2016.06.003