银基阳极析氧催化剂的制备及其性能研究

发布时间：2018-06-15 23:03

本文选题：电沉积 + 银基催化剂　；参考：《太原理工大学》2017年硕士论文

【摘要】：日益严重的环境问题和化石燃料能源危机,使来源丰富、清洁、可再生的氢气逐渐成为最有前景的替代能源之一。电解水制氢是技术发展比较成熟的一种制氢方式,其优点在于工艺过程简单、操作方便、产物纯净无污染。但电解水制氢技术存在着成本高、能耗大、能源转化效率低等问题,限制了其工业化发展。因此制备高效的水裂解催化剂是电解水制氢技术的关键。目前Ag基催化剂用于阳极水氧化析氧反应已有报道,Ag析氧催化剂具有析氧过电势低、结构易于调变的优点,但是其电流密度相对较低。而低过电势和高电流密度是高效析氧电催化的重要参数,对银基析氧催化剂进行结构设计和改性,可进一步降低能耗和提高效率。本文采用原位电沉积的方法对Ag基催化剂从形貌、晶面和金属氧化物复合三个方面进行了改性设计,通过XRD、SEM、EDS、XPS等表征手段对其结构、形貌、组成及价态进行分析,并通过循环伏安法、线性扫描伏安法、恒电位法对Ag基催化剂的电催化性能进行测试。具体研究内容主要分为以下三个部分:1.在乙酸钾中原位加入氨水作为电解质体系,以硝酸银为前驱体,采用原位恒电位沉积法制备了银基析氧催化剂薄膜。通过原位加入络合剂NH_3H_2O的方式,既能改变溶液酸碱度,又不造成Ag~+因与OH~-的键合作用而在溶液中的损失,还能改变Ag+在溶液中的金属存在形态,进而影响其阳极的沉积态。通过系列表征确定其活性组分为AgO。随着氨水加入量的调变,所得到的银基催化剂的形貌不同,进而影响其析氧催化性能,在氨水加入量与溶液中的Ag+完全络合且氨无过量时,所得到的Ag基催化剂催化水氧化性能最高。2.在硝酸钾中原位加入氨水作为电解质体系,以硝酸银为前驱体,通过原位恒电位沉积法制备银基析氧催化剂薄膜。选择硝酸钾为电解质,一方面在乙酸钾的基础上进一步减小电解质阴离子与Ag+的键合作用;另外舍弃了传统的缓冲溶液电解质作为质子载体的观念,利用络合剂NH3作为质子载体。研究结果表明其催化剂的活性组分仍为AgO,但随着氨水加入量的增加,所得到的银基催化剂的晶面发生了变化,逐渐从以AgO(202)面为主峰变为以(Ⅲ)面为主峰,并且在以(Ⅲ)为主峰时所得到的银基催化剂其催化水氧化性能较好。通过理论计算得到在碱性环境中AgO(Ⅲ)面是最稳定存在的晶面,且其在碱性环境中对OH-的氧化性能最佳,与实验数据相吻合。3.在硝酸钴中原位加入氨水作为电解质体系,以硝酸银为前驱体,利用原位恒电位沉积法成功制备了钴银双金属氧化物析氧催化剂薄膜。选择硝酸钴为电解质,在减小电解质阴离子与Ag~+的键合作用的基础上,利用Co~(2+)、Ag~+都能和NH3络合的性质,在阳极共沉积形成钴银双金属氧化物。通过实验发现当NH3加入量为150μL,沉积量为~1C时,其析氧催化性能最佳,研究表明其活性组分为钴银双金属氧化物,且为钴银协同催化。
[Abstract]:The increasingly serious environmental problems and the fossil fuel energy crisis make the rich, clean and renewable hydrogen gradually become one of the most promising alternative energy sources. Electrolysis water is a relatively mature technology for hydrogen production. Its advantages lie in simple process, easy operation and pure products without pollution. There are many problems such as high cost, high energy consumption and low efficiency of energy conversion, which restrict the development of its industrialization. Therefore, the key to the preparation of high efficient water cracking catalyst is the technology of electrolyzing water for hydrogen production. At present, the Ag based catalyst has been reported in the anodic oxygen evolution reaction of the anode. The Ag oxygen evolution catalyst has the advantages of low oxygen evolution potential and easy to adjust the structure. But its current density is relatively low. The low overpotential and high current density are the important parameters of high efficiency oxygen evolution electrocatalysis. The structure design and modification of the silver based oxygen evolution catalyst can further reduce energy consumption and improve efficiency. In this paper, the Ag based catalyst is composed of three compounds from the morphology, the crystal surface and the metal oxide. The modified design was carried out, and its structure, morphology, composition and valence state were analyzed by means of XRD, SEM, EDS and XPS. The electrocatalytic properties of Ag based catalysts were tested by cyclic voltammetry, linear sweep voltammetry and potentiostatic method. The main contents are divided into three parts: 1. in situ addition of potassium acetate As the electrolyte system and the silver nitrate as the precursor, the silver based oxygen evolution catalyst film was prepared by in situ potentiostatic deposition. By adding the complexing agent NH_3H_2O in situ, the solution can not only change the pH of the solution, but also do not cause the loss of the Ag~+ in the solution because of the cooperation with the OH~-, but also change the metal storage of the Ag+ in the solution. In the form, it affects the deposition of the anode. Through a series of characterization, it is determined that the active component is AgO. with the adjustment of the amount of ammonia water. The morphology of the silver based catalyst is different, and then it affects the catalytic performance of oxygen evolution. The Ag based catalyst is catalyzed by the Ag based catalyst when the amount of ammonia is added to the Ag+ in the solution and the ammonia is not overdose. The water oxidation performance is the highest.2. in the potassium nitrate in situ adding ammonia water as the electrolyte system. Silver nitrate is used as the precursor to prepare the silver based oxygen evolution catalyst film by in situ potentiostatic deposition. The potassium nitrate is selected as the electrolyte. On the one hand, the bonding effect of the electrosolution anion and the Ag+ is further reduced on the basis of potassium acetate; in addition, it is abandoned. The traditional buffer solution electrolyte is a proton carrier, using the complexing agent NH3 as a proton carrier. The results show that the active component of the catalyst is still AgO, but with the increase of the amount of ammonia water, the crystal surface of the obtained silver base catalyst changes from the main peak of the AgO (202) surface to the main peak of the (III) surface. The AgO (III) surface is the most stable crystal surface in the alkaline environment, and the oxidation performance of OH- in alkaline environment is the best. In accordance with the experimental data,.3. is in situ added to the cobalt nitrate as the electrolyte system. With silver nitrate as precursor, cobalt and silver bimetallic oxide oxide catalyst film was prepared by in situ potentiostatic deposition. Cobalt nitrate was selected as electrolyte. On the basis of reducing the bond of electrolyte anion and Ag~+, Co~ (2+), Ag~+ could be complex with NH3, and co deposition of cobalt and silver bimetallic oxidation was formed at the anode. It is found that when the amount of NH3 is 150 mu L and the amount of deposition is ~1C, the catalytic performance of oxygen evolution is the best. The study shows that the active component is cobalt silver bimetal oxide and CO and Ag co catalysis.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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