【作者】 李志杰；

【导师】 宋焱焱；

【作者基本信息】 东北大学 ， 分析化学， 2021， 硕士

【摘要】 直接甲醇燃料电池能够将甲醇燃料中的化学能直接转化为电能,其具有比能量密度高、能量转换效率高、运行温度低、携带方便等优点。甲醇氧化反应是直接甲醇燃料电池中的一个关键反应,因此,开发新型高效的甲醇电催化剂备受关注。铂基材料作为甲醇氧化反应电催化剂得到了广泛的研究,但资源短缺、价格高以及CO中间体毒化导致的催化活性受损阻碍了其大规模商业化进程。镍基材料,在碱性介质中对甲醇具有较好的催化活性且价格相对低廉,有望成为碱性介质中甲醇阳极氧化反应的主要催化剂。然而,镍基催化剂也会被CO中间体毒化,使催化剂的活性降低。本论文以TiO2纳米管阵列为载体,制备出具有高甲醇氧化活性的催化剂TiO2@CoNi。利用催化剂中的p-n异质结结构,TiO2@CoNi能够在可见光条件下产生大量的光生空穴,实现催化剂的抗毒化作用。具体的研究内容如下:(1)以电化学阳极氧化法制备的TiO2纳米管阵列为载体,采用水热法在二氧化钛纳米管修饰CoNi双组分纳米片,并探究了双组分纳米片的形成机理。利用CoNi二元组分的双功能机理增强了催化剂催化活性,降低了甲醇氧化反应的起峰电位。同时,也探究了双功能机理对催化剂催化活性的增强情况,并进一步考察了不同比例Co/Ni复合催化剂的电化学甲醇氧化性能,结果显示催化剂TiO2@CoNi Sl(TiO2@CoNi Sample 1)在0.60 V具有最高的质量电流密度(22.94 mA mg-1)和活性面积电流密度(1.10 mAcm-2)。(2)通过p-n异质结的构建,将光催化引入TiO2@CoNi电催化甲醇氧化反应体系,实现了光辅助催化剂抗毒化性能的提高。在模拟太阳光条件下,具有p-n异质结的催化剂TiO2@CoNi能够将产生的大量电子空穴对分离,分离后的空穴与NiOOH表面吸附的CO中间体发生氧化反应以释放Ni的活性位点,从而增强了催化剂的抗毒化能力。基于抗毒化机理,与暗态条件下的稳定性测试相比,TiO2@CoNi S1在模拟太阳光条件下的长期循环稳定性测试中,电流密度下降了 35%,表明了催化剂的抗毒化性能得到增强。催化剂光辅助电催化甲醇氧化反应体系的建立,增强了镍基催化剂的抗毒化能力,使镍基材料在甲醇催化领域具有更广阔的应用前景。更多还原

【Abstract】 Direct methanol fuel cells(DMFCs)can directly converts the chemical energy of methanol into electrical energy.It has the advantages including high specific energy density,high energy conversion efficiency,low operating temperature,and convenient carrying,etc.Methanol oxidation reacation(MOR)is a key reaction in DMFCs,thus the development of novel and efficient MOR electrocatalysts has attracted tremendous attention.Although Pt-based materials have been extensively investigated as the MOR electrocatalysts,its resource scarcity,high price and activity loss due to CO intermediate species poisoning impeded its pratical application.Ni-based materials are expected to be the main catalyst for MOR in alkaline media because of their good catalytic activity and relatively low price.However,nickel-based catalysts can also be poisoned by CO intermediate species,reducing the activity of the catalyst.In this paper,the preparation of high methanol oxidation activity of the catalyst TiO2@CoNi was proposed based on TiO2 nanotube array.By using the p-n heterojunction structure in the catalyst,TiO2@CoNi can produce a large number of photogenerated holes under visible light conditions,and realize the toxicity resistance of the catalyst.The specific research contents are as follows:(1)CoNi bi-component nanosheets modificated TiO2 nanotube arrays were prepared by hydrothermal modification based on TiO2 nanotube arrays synthesized through electrochemical anodic oxidation,and the formation mechanism of the bi-component nanosheets was investigated.The catalytic activity of the catalysts was enhanced by the bifunctional mechanism of the two components of Co and Ni,and reduced the onest potential of methanol oxidation reaction.Meanwhile,the enhancement of the catalytic activity of the catalyst by the bifunctional mechanism was also explored,and the electrochemical methanol oxidation performance of the composite catalysts with different ratios of Co/Ni was further investigated.The results showed that the TiO2@CoNi S1 had the highest mass current density(22.94 mA mg-1)and active area current density(1.10 mA cm-2)at 0.60 V.(2)By the construction of p-n heterojunction,introducing photocatalysis into TiO2@CoNi electrocatalytic methanol oxidation reaction system,the anti-poisoning performance of photoassisted catalyst was improved.Under simulated sunlight conditions,the catalyst TiO2@CoNi with p-n heterojunction can separate a large number of generated electron holes pairs,which oxidized with CO intermediates adsorbed on the surface of NiOOH to release active Ni sites,thus enhancing the anti-poisoning of the catalyst.Based on the resistance mechanism,compared with the stability test under dark state,the current density of TiO2@CoNi S1 decreased by 35%in the long-term cycle stability test under simulated sunlight condition,indicating that the resistance of the catalyst was enhanced.The establishment of photoassisted electrocatalytic methanol oxidation reaction system has enhanced the ability of Ni-based catalyst to anti-poisoning,so that Ni-based materials have a wider application prospect in the field of methanol catalysis.更多还原