【作者】 胡晓明；

【导师】 夏定国；

【作者基本信息】 北京工业大学 ， 环境科学， 2012， 博士

【摘要】 酞菁类物质因其特殊的大环共轭结构而具有良好电催化性能，通过改变其共轭环上的取代基及中心金属原子和分子的聚集方式实现分子设计，这种结构的可调变性赋予它作为电催化剂性能开发的广阔空间。燃料电池是一种环境友好的发电装置，阴极氧还原催化剂对燃料电池的性能起着关键作用。燃料电池阴极催化剂通常分为铂系及非铂催化剂,贵金属铂及其合金具有良好的电催化性能,但该类催化剂存在价格昂贵及资源不足的问题，限制了燃料电池的商业化发展。因此,开发新型高效、廉价的可替代贵金属的催化剂及提高催化剂的性能以实现商业化是当前的重要任务。在非铂系催化剂研究中酞菁、卟啉等大环共轭配合物倍受人们关注，成为燃料电池最有希望的催化剂材料，被认为是铂系催化剂有应用前景的替代品之一。目前稳定性制约金属酞菁类配合物氧还原催化剂向实用化方向发展的最主要问题。在酞菁大环配合物催化氧还原的过程中会产生具有强氧化性的过氧化氢，并且随着反应的进行不断积累，严重腐蚀大环结构。因而，如何提高金属酞菁类配合物作为氧还原催化剂的稳定性是燃料电池催化剂研究领域中的一项非常重要的任务。本研究选择平面共轭双核酞菁配合物作为氧还原催化剂，通过双核酞菁配合物扩大的平面π共轭分子结构提高其作为氧还原催化剂的稳定性。鉴于其具有较好的电催化性能，本文将进一步研究其作为电催化剂进行脱氯、脱硝的性能。本课题的主要研究内容为：以邻苯二甲酸酐、均苯四甲酸酐和金属盐为原料，在尿素和钼酸铵存在下采用固相法合成了双核酞菁铁，粗产物经水洗、有机溶剂萃洗后经硅胶层析柱纯化。产物经红外光谱、UV-Vis电子吸收光谱、HNMR光谱、元素分析、激光解吸电离飞行质谱（LDT-TOF-MS）进行表征。利用CV和RDE方法研究了碳载双核酞菁铁的氧还原催化性能。结果表明，双核酞菁铁催化剂的在酸性介质中表现出较理想的氧还原催化性能，同时具有抗甲醇性能。与单核酞菁铁催化剂相比碳载双核酞菁铁催化剂的起始电位正移约100mV，双核酞菁铁配合物对氧还原的电催化活性大于单核酞菁铁配合物。旋转圆盘电极方法研究结果表明双核酞菁铁催化剂催化氧分子经过4e电子过程。通过恒电位计时电流测试方法研究碳载双核酞菁铁催化剂的稳定性，结果表明双核酞菁铁与单核酞菁铁相比在酸性溶液中作为氧还原催化剂其稳定性有显著提高。首次采用原位法将邻二腈基苯，1，2，4，5-苯四甲腈，FeCl₂·4H₂O按一定的摩尔配比在有机溶剂中与碳纳米管混合，合成了双核酞菁铁/碳纳米管复合物，通过测试产物在DMSO溶液中的电子吸收光谱确定双核酞菁铁生成，分别通过XRD和TEM考察了双核酞菁铁在碳纳米管表面的形貌和结构，研究了不同合成条件对双核酞菁铁/碳纳米管复合物产率的影响。通过改变反应时间来考察其对双核酞菁铁/碳纳米管复合物的形貌的影响，发现随着反应时间的加长，双核酞菁铁分子堆积到碳纳米管壁上的量增多，双核酞菁铁分子在碳纳米管壁包覆的厚度明显增大。利用CV和RDE方法研究了双核酞菁铁/碳纳米管复合物催化剂的氧还原催化性能。实验结果表明，双核酞菁铁/碳纳米管复合物在酸性介质中表现出较强的氧还原催化性能，双核酞菁铁催化剂催化氧分子经过4e电子过程。通过对电极进行恒电位下计时电流测试考察了双核酞菁铁/碳纳米管复合物作为氧还原催化剂的稳定性，结果表明原位法合成的双核酞菁铁/碳纳米管复合物在酸性溶液中氧化电流衰减缓慢，在酸性溶液中作为氧还原催化剂的稳定性优于碳载双核酞菁铁。以双核酞菁铁/碳纳米管复合物作为电催化剂还原含氯有机物阿特拉津，通过改变温度、pH值、电解质、催化剂用量、电解池的构造、反应体系流动类型以及电化学条件的设置等条件研究各影响因素与去除率的关系。双核酞菁铁/碳纳米管复合物能有效的降解含氯有机物阿特拉津，48h后降解率可达98%以上。采用计时电流法，电压的设置对反应去除率有一定的影响，电压为0.55V时效果最好。阿特拉津在电催化剂双核酞菁铁/碳纳米管复合物的作用下发生脱氯羟基化反应，产物为2-羟基-4-乙胺基-6-异丙胺基-1,3,5-三嗪，毒性大大降低。此研究不仅为酞菁的应用开拓了新领域，更为研究有效降解内分泌干扰物阿特拉津的新技术，为治理农药造成的水体面源污染问提供基础研究的参考。本文首次将双核酞菁铁/碳纳米管复合物用于电催化还原硝酸盐的实验中，双核酞菁铁/碳纳米管复合物具有良好的选择性。电流强度、初始pH值及催化剂的用量对催化反应的活性和选择性都有影响。在电流密度为2.3mA/cm²，pH值为6.4，NO₃^--N含量为20mg·L^-1的条件下，反应20h后硝酸盐氮的浓度变13.7mg·L^-1，去除率达31.5%，有极少量副产物产生，去除率有待进一步提高，为脱硝研究提供一种新型催化体系，也为酞菁类物质的应用提供的更广阔的空间。更多还原

【Abstract】 Due to the large p-conjugated system in macrocycle, phthalocyanine compoundsnot only show good electrocatalytic activity, but also could be modified the structureof phthalocyanine molecule, This is by adjusting the central metal atom and peripheralsubstituent ground or the congregation morphology of the molecular to obtain therequired physical and chemical properties. The modifications of the structure makethem could be used in the fields of electrocatalytic activity widely in the future.Fuel cells is a kind of environmental friendly device that can convert chemicalenergy directly to electricity. Cathode oxygen reduction reaction （ORR） catalyst is thekey materials of Fuel Cells. Currently, Platinum and its alloys are good catalysts forORR used for fuel cell in low temperature condition, however, the high cost andshortage hinders its commercialization. In the effort to reduce the cost as well as toimprove the reliability of fuel cell catalysts, non-Pt （or non-noble metal） catalystshave attracted great attention over the last several decades. Among the non-noblemetal catalysts explored, transition metal-N4chelates such as metallophthalocyaninesand metalloporphyrins have shown great promise as candidates for fuel cell ORRcatalysts. Phthalocyanine compounds are considered as one of the most promisingcatalyst material to replace the noble metal.The stability of metallophthalocyanines is the main factor, which restrains thedevelopment of practicality as ORR catalysts. Being the ORR catalystsmetallphthalocyanine complexes will lead to the formation of a little amount of H₂O₂which will erode the Pc-ring and carrier badly, and then destroy the structure ofcatalysts. Thus how to improve the stability of metallophthalocyanines as the ORRcatalysts is all-important task in the fields of ORR electrocatalysts.In this study, we choose a planar binuclear iron phthalocyanine as ORR catalystand plan to improve the stability of ORR catalysts through its large p electronconjugated system. The main results and conclusions are as follows:Two binuclear metal phthalocyanine complexes are synthesized by solid routeUsing o-phthalic anhydride, pyromellitic dianhydride and metal salt as the rawmaterials at the present of urea and ammonium molybdate. The crude product waswashed with ammonia solution, hydrochloric acid, and water, followed by anextraction process with ethanol and tetrahydrofuran （THF） to purify the product. Afterthis extraction, the resultant dark blue solid was further purified by silica columnchromatography. The products have been characterized by IR, UV-Vis, HNMR,LDT-TOF-MS and elemental analysis respectively.The ORR catalytic activity of binuclear iron phthalocyanine （bi-FePc） has beeninvestigated using CV and RDE technique. The results show that this bi-FePc/Ccatalyst can catalyze a direct4-electron reduction of oxygen to water. The bi-FePc/C showed superior activity, has a about100mV higher ORR onset potential than theFePc/C catalyst. Chronoamperometry tests were conducted to examine the stability ofthe bi-FePc/C catalyst, and the results show that this bi-FePc/C electrocatalyst has abetter stability than the mononuclear FePc/C catalyst in acidic solution. This catalystalso has methanol tolerance, suggesting that it should be able to improve theperformance of a direct methanol fuel cell cathode.We successfully synthesized a planar binuclear iron phthalocyanine on carbonnanotube （bi-FePc/MWNT） catalyst for the oxygen reduction reaction by in situmethod for the first time. The electronic absorption spectra in a dimethyl sulfoxide（DMSO） solution of the products have been determined and indicated that bi-FePcwas successfully synthesized by this process. The influence of the reactants molarratio on the yield of bi-FePc/MWNT has been studied. The bi-FePc/MWNT catalystwas characterized by XRD, TEM and the results show that the bi-FePc was coateduniformly on the carbon nanotube. According to the high-resolution TEM image theclear lattice fringes can be observed.The effect of the time of the whole reaction process on the morphology of thebi-FePc/MWNT was discussed. The amount of molecules of bi-FePc coated on thecarbon nanotube was more and more as time prolonging.Using CV and RDE technique, it was confirmed that this bi-FePc/MWNT couldshow a nearly perfect ORR catalytic activity and stability in acidic solution. Thisnovel bi-FePc/MWNT catalyst can catalyze a direct4-electron reduction of oxygen towater. In comparison with a mononuclear FePc catalyst, this catalyst showed superioractivity and enhanced stability. This catalyst also has methanol tolerance, suggestingthat it should be able to improve the performance of a direct methanol fuel cellcathode.With dual-core iron phthalocyanine/carbon nanotube composites aselectrocatalysts chlorinated organics reduction of atrazine, by changing thetemperature, pH, electrolyte, the amount of catalyst, electrolytic cell structure, andelectrochemical reaction type of flow conditions set of conditions, such as removal ofthe influence factors and the relationship. Binuclear iron phthalocyanine/carbonnanotube composites can effectively degrade chlorinated organic compounds atrazine,48h after the degradation rate of up to98%. Using CA, the removal of the voltagesettings on the reaction to a certain extent, the voltage of0.55V is the best. Atrazine inthe dual-core power of iron phthalocyanine catalyst/carbon nanotube compositematerial under the action of hydroxyl dechlorination reaction, the product is2-hydroxy-4-amine base-6-isopropylamine-1,3,5-triazine, toxicity greatly reduced. Thisstudy not only the application of phthalocyanine opened up new areas of researchmore efficient degradation of endocrine disruptors atrazine new technologies for the treatment of pesticides resulting in contamination of water sources to provide a decentbasic research reference.This is the first time using dual-core iron phthalocyanine/carbon nanotubecomposite for electrocatalytic reduction of nitrate experiments; it has a certain natureof the electrocatalytic reduction of nitrate. The catalytic reduction of nitrate in waterhas been studied using bi-FePc loaded on multi-walled carbon nanotubes（bi-FePc/MWNT） as electrocatalyst. The results show that, bi-FePc/MWNT cancatalysis to remove nitrate in the water and shows a good selectivity towards nitrogen.The concentration of NO₃^--N was reduced from20mg·L^-1to13.7mg·L^-1in currentdensity of2.3mA/cm2, pH6.4and NO₃^--N of20mg·L^-1in the prstine water after20h. The removing rate of nitrate is up to31.5%. The catalytic activity and selectivitydepends on pH value, current density and catalyst amount.A small amount ofby-products are generated, but need to further improve the removal rate. But for thedenitrification study provide a new catalyst system, has made some contribution. Alsofor the application of phthalocyanine materials, provided broader space.更多还原