-
近年来,随着纺织、造纸、矿山开采等行业的发展,水体中染料和重金属污染日趋严重[1-4],且染料废水属于长期困扰人们生活的难处理的工业废水之一[5]. 研究表明,燃料电池技术可以在降解污染物的同时将化学能转换为电能[6-9],阳极发生电子-空穴对分离,分解水中有机污染物,产生的电子通过外电路传导到阴极,发生氧化还原反应[10]。燃料电池技术既能较好的解决环境污染问题,又可以产生新的能源,实现节能环保[11].
g-C3N4是一种具有适宜禁带宽度的半导体材料,其化学性质稳定[12],且不溶于乙醇、水、甲苯等溶剂. 此外,g-C3N4还具有廉价、无毒、原材料易得等优点[13],被人们广泛应用。g-C3N4具有独特的电子结构以及较大的比表面积,为光催化过程提供更多的活性位点,有利于提高光的捕获率,再者,高的比表面积材料可减少光生电子与空穴对的扩散路径,增加反应动力学,被广泛应用于光催化去除无机、有机污染物[14]、氧化还原反应[15]、锂离子电池[16]、生物燃料电池[17]等领域.
过渡金属二硫族化合物(TMDs)因其带隙可控、电子迁移率高和尺寸可达原子尺度等性能特点,被广泛应用于电池、超级电容器、光伏材料、催化剂等领域[18-20]。TMDs主要包括二硫化钼(MoS2)、硒化钨(WSe2)、和硒化钼(MoSe2)等[21]. 二硫化钼(MoS2)是一个典型的层状化合物,层间是以微弱的范德华力结合在一起[22]. 二硫化钼具有低成本、边沿暴露活性位点可调控、耐酸性条件等优点[23],属于n型半导体;在光催化剂、电化学等领域广泛应用[24-25]。但MoS2电导率较差,限制了其广泛应用[25, 27]. 为克服这一缺点,可将其粒径减小到纳米尺寸,与导电剂混合,通过改变形貌,将二维纳米片转为稳定的三维矩阵,或通过添加模板减小MoS2纳米片的堆叠,以提高其电子传递速率[24,27].
WSe2具有高的光吸收、阳离子间的层状排列、抗光腐蚀能力强等优点,是光电转换和光伏太阳能转换的重要材料。目前,国内外对其形貌的研究相对较少,且较少合成出比纳米WSe2纯度更高的其他形貌的WSe2[28]. 由于WSe2和MoS2已经表现出p型和n型半导体的性质[29],MoS2和WSe2之间可以形成内电场,促进电子空穴的分离. WSe2可作为辅助剂,与MoS2形成p-n异质结,提高材料的电子和空穴分离效率,进一步提高催化效率.
本文通过水热法将硒化钨和二硫化钼进行复合,形成MoS2基范德华异质结复合材料MoS2/WSe2(MW),并对其进行XRD、SEM以及TEM表征. 采用g-C3N4作为阴极,MW作为阳极,构建自偏压式燃料电池,研究其对不同类型污染物的去除性能. 值得注意的是,为探求能源的最小消耗以及电池的实际应用性能,所有试验均无需光照,本实验利用电池自身产生的内偏压进行污染物降解,能耗仅为曝气。研究表明,MW表现出比MoS2、WSe2更为优越的催化活性,并通过改变污染物浓度以及污染物种类探究该电池对污染物去除效果的影响.
g-C3N4-MoS2/WSe2自偏压系统构建与不同类型污染物同时去除性能研究
Study on simultaneous removal performance of g-C3N4-MoS2 /WSe2 Self-bias system with different types of pollutants
-
摘要: 由于工业化进程的不断推进,染料与重金属废水被非法排入自然水体,水体污染问题日益严峻。为实现两种污染物的同时去除,本文通过调控合成MoS2/WSe2(MW)异质结复合催化材料,提高其催化活性. 黑暗条件下,以MoS2、WSe2以及MW为阳极材料,g-C3N4为阴极材料组建自偏压燃料电池系统,实现在降解有机染料的同时,去除水体中的重金属离子. 通过调控参数,探究影响染料与重金属去除的因素. 研究表明,影响重金属和有机染料去除效果的因素有pH、电解质溶液浓度、重金属溶液浓度. 当溶液pH=5,电解质溶液浓度为0.1 mol·L−1,铜离子浓度为4 mg·L−1时,重金属的去除率为64.3%. 当溶液pH=5,电解质溶液浓度为0.2 mol·L−1,铜离子浓度为2 mg·L−1时,有机染料罗丹明B的去除率为99.5%. 该系统在无外加光照条件下,实现不同类型污染物同时去除,并产生约240 mV的电压,为无光条件下光催化材料的实际应用提供新思路.Abstract: Due to the continuous advancement of industrialization, dye and heavy metal wastewater is illegally discharged into natural water bodies, which makes the problem of water pollution more and more serious. In order to realize simultaneous degradation of the two pollutants, MoS2/WSe2 (MW) heterojunction composite was synthesized to improve its catalytic activity in this paper. Under dark conditions, the self-biased fuel cell was constructed with MoS2, WSe2 and MW as anode materials, g-C3N4 as cathode material to degrade organic pollutants and remove heavy metal ions in water. By adjusting the parameters and exploring the factors affecting the removal of dyes and heavy metals, the study showed that the removal efficiency of heavy metals and organic dyes was affected by pH, electrolyte and heavy metal concentration. When the pH 5, electrolyte solution concentration was 0.1 mol·L−1, and copper ion concentration was 4 mg·L−1, the removal rate of heavy metals was 64.3%. When the pH 5, electrolyte solution concentration was 0.2 mol·L−1, and copper ion concentration was 2 mg·L−1, the removal rate of organic dye rhodamine B was 99.45%. This system can remove different kinds of pollutants and generate a voltage of about 240 mV at the same time in the absence of illumination, which provides a new idea for the practical application of photocatalytic materials in dark conditions.
-
Key words:
- g-C3N4 /
- MoS2/WSe2 /
- self-biased fuel cell /
- dye /
- heavy metal
-
-
[1] FU F, WANG Q. Removal of heavy metal ions from wastewaters: a review [J]. Journal of Environmental Management, 2011, 92(3): 407-418. [2] LI Z, MA Z, KUIJP T J, et al. A review of soil heavy metal pollution from mines in China: pollution and health risk assessment [J]. Science of Total Environment, 2014, 468/469: 843-853. doi: 10.1016/j.scitotenv.2013.08.090 [3] LI Z, CHEN J, GUO H, et al. Triboelectrification-enabled self-powered detection and removal of heavy metal ions in wastewater [J]. Advanced Materials, 2016, 28(15): 2983-2991. doi: 10.1002/adma.201504356 [4] RABÉ K, LIU L, NAHYOON N A, et al. Enhanced Rhodamine B and coking wastewater degradation and simultaneous electricity generation via anodic g-C3N4/Fe0(1%)/TiO2 and cathodic WO3 in photocatalytic fuel cell system under visible light irradiation [J]. Electrochimica Acta, 2019, 298: 430-439. doi: 10.1016/j.electacta.2018.12.121 [5] 张林, 冯江涛, 王宁, 等. 甘氨酸改性TiO2材料的合成及其对染料的吸附性能 [J]. 环境化学, 2018, 37(12): 2621-2629. doi: 10.7524/j.issn.0254-6108.2018012905 ZHANG L, FENG J T, WANG N, et al. Preparation of glycine functionalized TiO2 adsorbent and its adsorption performance for organic dyes [J]. Environmental Chemistry, 2018, 37(12): 2621-2629(in Chinese). doi: 10.7524/j.issn.0254-6108.2018012905
[6] WANG Y, WANG Y, SONG X M, et al. BiOCl-based photocathode for photocatalytic fuel cell [J]. Applied Surface Science, 2020, 506: 144949. doi: 10.1016/j.apsusc.2019.144949 [7] RABÉ K, LIU L, NAHYOON N A, et al. Visible-light photocatalytic fuel cell with Z-scheme g-C3N4/Fe0/TiO2 anode and WO3 cathode efficiently degrades berberine chloride and stably generates electricity [J]. Separation and Purification Technology, 2019, 212: 774-782. doi: 10.1016/j.seppur.2018.11.089 [8] LIU N, HAN M, SUN Y, et al. A g-C3N4 based photoelectrochemical cell using O2/H2O redox couples [J]. Energy & Environmental Science, 2018, 11(7): 1841-1847. [9] BAI Y, YANG P, WANG L, et al. Ultrathin Bi4O5Br2 nanosheets for selective photocatalytic CO2 conversion into CO [J]. Chemical Engineering Journal, 2019, 360: 473-482. doi: 10.1016/j.cej.2018.12.008 [10] WANG H-N, CHEN X, CHEN R, et al. A ternary hybrid CuS/Cu2O/Cu nanowired photocathode for photocatalytic fuel cell [J]. Journal of Power Sources, 2019, 435: 226766. doi: 10.1016/j.jpowsour.2019.226766 [11] LI M, LIU Y, DONG L, et al. Recent advances on photocatalytic fuel cell for environmental applications-The marriage of photocatalysis and fuel cells [J]. Science of Total Environment, 2019, 668: 966-978. doi: 10.1016/j.scitotenv.2019.03.071 [12] 吴斌, 方艳芬, 任慧君, 等. g-C3N4光催化降解2, 4-DCP的活性及机理 [J]. 环境化学, 2017, 36(7): 1484-1491. doi: 10.7524/j.issn.0254-6108.2017.07.2016102508 WU B, FANG Y F, REN H J, et al. Activity and mechanism of photocatalytic degradation for 2, 4-DCP over g-C3N4 [J]. Environmental Chemistry, 2017, 36(7): 1484-1491(in Chinese). doi: 10.7524/j.issn.0254-6108.2017.07.2016102508
[13] 张聪, 米屹东, 马东, 等. CeO2/g-C3N4光催化剂的制备及性能 [J]. 环境化学, 2017, 36(1): 147-152. doi: 10.7524/j.issn.0254-6108.2017.01.2016051706 ZHANG C, MI Y D, MA D, et al. Preparation and photocatalytic performance of CeO2/g-C3N4 photocatalysts [J]. Environmental Chemistry, 2017, 36(1): 147-152(in Chinese). doi: 10.7524/j.issn.0254-6108.2017.01.2016051706
[14] LAN M, FAN G, YANG L, et al. Enhanced visible-light-induced photocatalytic performance of a novel ternary semiconductor coupling system based on hybrid Zn-in mixed metal oxide/g-C3N4 composites [J]. RSC Advances, 2015, 5(8): 5725-5734. doi: 10.1039/C4RA07073A [15] ZHAO L, WANG L, YU P, et al. A Chromium Nitride/carbon nitride containing graphitic carbon nanocapsule hybrid as a pt-free electrocatalyst for oxygen reduction [J]. Chemical Communications, 2015, 51(62): 12399-12402. doi: 10.1039/C5CC04482K [16] LUO W B, CHOU S L, WANG J Z, et al. A metal-free, free-standing, macroporous graphene@ g-c3n4 composite air electrode for high-energy lithium oxygen batteries [J]. Small, 2015, 11(23): 2817-2824. doi: 10.1002/smll.201403535 [17] GAI P, SONG R, ZHU C, et al. A ternary hybrid of carbon nanotubes/graphitic carbon nitride nanosheets/gold nanoparticles used as robust substrate electrodes in enzyme biofuel cells [J]. Chemical Communications, 2015, 51(79): 14735-14738. doi: 10.1039/C5CC06062A [18] HAN D, MING W, XU H, et al. Chemical trend of transition-metal doping in WSe2 [J]. Physical Review Applied, 2019, 12(3): 034038. doi: 10.1103/PhysRevApplied.12.034038 [19] YIN C, WANG X, CHEN Y, et al. A ferroelectric relaxor polymer-enhanced p-type WSe2 transistor [J]. Nanoscale, 2018, 10(4): 1727-1734. doi: 10.1039/C7NR08034D [20] WU J M, SUN Y-G, CHANG W E, et al. Piezoelectricity induced water splitting and formation of hydroxyl radical from active edge sites of MoS2 nanoflowers [J]. Nano Energy, 2018, 46: 372-382. doi: 10.1016/j.nanoen.2018.02.010 [21] XUE H, DAI Y, KIM W, et al. High photoresponsivity and broadband photodetection with a band-engineered WSe2/SnSe2 heterostructure [J]. Nanoscale, 2019, 11(7): 3240-3247. doi: 10.1039/C8NR09248F [22] 齐中, 王熙, 李来胜, 等. 基于水热法制备的TiO2 /MoS2复合光催化剂及其光催化制氢活性 [J]. 环境化学, 2016, 35(5): 1027-1034. doi: 10.7524/j.issn.0254-6108.2016.05.2015112403 QI Z, WANG X, LI L, et al. Development of TiO2 /MoS2 by hydrothermal method for photocatalytic hydrogen generation under solar light [J]. Environmental Chemistry, 2016, 35(5): 1027-1034(in Chinese). doi: 10.7524/j.issn.0254-6108.2016.05.2015112403
[23] TEICH J, DVIR R, HENNING A, et al. Light and complex 3D MoS2/graphene heterostructures as efficient catalysts for the hydrogen evolution reaction [J]. Nanoscale, 2020, 12(4): 2715-2725. doi: 10.1039/C9NR09564K [24] MUKHERJEE S, BISWAS S, DAS S, et al. Solution-processed, hybrid 2D/3D MoS2/Si heterostructures with superior junction characteristics [J]. Nanotechnology, 2017, 28(13): 135203. doi: 10.1088/1361-6528/aa5e42 [25] AGARWAL V, VARGHESE N, DASGUPTA S, et al. Engineering a 3D MoS2 foam using keratin exfoliated nanosheets [J]. Chemical Engineering Journal, 2019, 374: 254-262. doi: 10.1016/j.cej.2019.05.185 [26] ANWER S, HUANG Y, LI B, et al. Nature-Inspired, Graphene-Wrapped 3D MoS2 Ultrathin Microflower Architecture as a High-Performance Anode Material for Sodium-Ion Batteries [J]. ACS Applied Materials and Interfaces, 2019, 11(25): 22323-22331. doi: 10.1021/acsami.9b04260 [27] CHENG R, LI D, ZHOU H, et al. Electroluminescence and photocurrent generation from atomically sharp WSe2/MoS2 heterojunction p-n diodes [J]. Nano Letters, 2014, 14(10): 5590-5597. doi: 10.1021/nl502075n [28] PESCI F M, SOKOLIKOVA M S, GROTTA C, et al. MoS2/WS2 heterojunction for photoelectrochemical water oxidation [J]. ACS Catalysis, 2017, 7(8): 4990-4998. doi: 10.1021/acscatal.7b01517 [29] WU J M, CHANG W E, CHANG Y T, et al. Piezo-catalytic effect on the enhancement of the ultra-high degradation activity in the dark by single- and few-layers MoS2 nanoflowers [J]. Advanced Materials, 2016, 28(19): 3718-3725. doi: 10.1002/adma.201505785 [30] LIU W, WANG M, XU C, et al. Facile synthesis of g-C3N4/ZnO composite with enhanced visible light photooxidation and photoreduction properties [J]. Chemical Engineering Journal, 2012, 209: 386-393. doi: 10.1016/j.cej.2012.08.033 [31] SI K, MA J, LU C, et al. A two-dimensional MoS2/WSe2 van der Waals heterostructure for enhanced photoelectric performance [J]. Applied Surface Science, 2020, 507: 145082. doi: 10.1016/j.apsusc.2019.145082