钼掺杂的铁钴三元羟基氧化物的合成及电催化性能研究

发布时间：2018-12-23 18:19

【摘要】：当前,由于化石燃料的燃烧是获得能量的主要途径,造成了环境污染以及能源日益枯竭的问题,因此开发清洁能源是当下最迫切的问题。氢气是当前应用最广泛的清洁能源,使用电解水制氢也是当前最常用的制取氢能源的途径。目前,电解水的半反应氧析出反应(OER)是技术发展的瓶颈,研究出高电催化性能的催化剂来降低氧析出反应所需要的过电位是当下的研究重点。地壳中含量充足的3d过渡金属的羟基氧化物表现出高的电催化活性并且经济实惠。我们着手向二元的FeCo羟基氧化物中引入具有高氧化态的金属钼,以提高FeCo羟基氧化物的电催化活性,并尝试向其中添加高催化活性的物质对其的电催化活性进一步进行提高。在本文中,我们使用溶胶-凝胶法分别合成钼和钨掺杂的胶体的FeCo羟基氧化物,对二者的OER催化活性进行测定,结果显示二者在电催化性能上十分相近,并且OER催化活性很高。并同样使用溶胶-凝胶法合成不含金属Mo的FeCo羟基氧化物,且合成具有高催化活性的二元FeCo氢氧化物FeCo LDH,测定二者的电化学性能,通过电化学测试得出钼的掺杂在很大程度上提高了 FeCo羟基氧化物的活性,并且FeCoMo羟基氧化物在达到电流密度为10mA/cm2时所需的过电位比FeCo LDH低了约78mV,且比目前公认的顶级碱性OER催化剂之一的FeCo LDH的性能还高,有实际的投产意义。对合成的胶体FeCoMo羟基氧化物样品进行高温退火处理,通过XRD的表征证明其存在Fe、Co、Mo三相的分离。其电催化性能与具有无定形结构的FeCoMo羟基氧化物相比有很大的差距,证明无定形的非晶结构在电催化性能上更有优势,侧面证明了溶胶-凝胶法的优越性。为了使FeCoMo羟基氧化物的电催化性能进一步提高,我们向合成的FeCoMo羟基氧化物中原位掺杂具有多活性位点的石墨烯,通过电化学测试发现石墨烯的掺杂在一定程度上提高了 FeCoMo羟基氧化物的活性。但由于石墨烯价格过高,其掺杂的FeCoMo羟基氧化物还不具有实际投产的意义。
[Abstract]:At present, the burning of fossil fuels is the main way to get energy, which results in environmental pollution and energy depletion, so the development of clean energy is the most urgent problem. Hydrogen is the most widely used clean energy at present. Using electrolytic water to produce hydrogen is also the most commonly used way to produce hydrogen energy. At present, semi-reactive oxygen precipitation reaction (OER) in electrolytic water is the bottleneck of technological development. The research focus is to study the overpotential needed to reduce the oxygen precipitation reaction with high electrocatalytic performance catalyst. The hydroxyl oxides of transition metals with sufficient content in the crust show high electrocatalytic activity and are economical and economical. We began to introduce highly oxidized molybdenum into binary FeCo hydroxyl oxides in order to improve the electrocatalytic activity of FeCo hydroxyl oxides and try to increase the electrocatalytic activity of FeCo hydroxyl oxides by adding high catalytic activity to them. In this paper, the FeCo hydroxyl oxides of molybdenum and tungsten doped colloids were synthesized by sol-gel method, and their OER catalytic activities were determined. The results show that the catalytic activity of OER is very similar and the catalytic activity of OER is very high. FeCo hydroxyl oxides without metal Mo were also synthesized by sol-gel method, and binary FeCo hydroxides with high catalytic activity were synthesized to determine their electrochemical properties. The electrochemical tests show that the doping of molybdenum greatly improves the activity of FeCo hydroxyl oxides, and the overpotential required by FeCoMo hydroxyl oxides when the current density is 10mA/cm2 is about 78 MV lower than that of FeCo LDH. The performance of FeCo LDH is higher than that of FeCo LDH, which is one of the top alkaline OER catalysts. The synthesized colloidal FeCoMo hydroxyl oxide samples were annealed at high temperature and characterized by XRD. It was proved that there were three phase separation of Fe,Co,Mo. Compared with FeCoMo hydroxyl oxides with amorphous structure, its electrocatalytic performance is far from that of amorphous structure, which proves that amorphous structure has more advantages in electrocatalytic performance, and the advantages of sol-gel method are also proved. In order to further improve the electrocatalytic performance of FeCoMo hydroxyl oxides, we doped graphene with multiple active sites into the synthesized FeCoMo hydroxyl oxides. It was found by electrochemical test that the activity of FeCoMo hydroxyl oxides was improved to some extent by graphene doping. However, because of the high price of graphene, its doped FeCoMo hydroxyl oxide has no practical significance.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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