Ag-Cu纳米催化剂的制备及其锌空气电池的研究

发布时间：2019-05-12 16:27

【摘要】：金属空气电池作为一种高效、洁净的新能源技术,受到了越来越多的关注。氧还原反应电催化剂的研究则一直是金属空气电池研究的热点问题。为了提高氧还原反应的催化活性、增加催化剂的稳定性、降低催化剂的成本,Ag基催化剂的研究具有非常重要的意义。本论文主要的研究内容为Ag-Cu纳米催化剂的催化活性。论文中分别采用伽尔瓦尼置换反应和电化学沉积法制备Ag-Cu双金属纳米枝晶和Ag-Cu纳米合金。电化学方法测试了Ag-Cu催化剂对氧还原反应的催化活性,并结合物理表征研究了Ag-Cu纳米催化剂提高氧还原反应催化活性的机制。论文的主要实验结论如下:(1)伽尔瓦尼置换反应制备Ag-Cu催化剂。Ag-Cu催化剂直接负载在泡沫镍集流极上,形成无碳、无粘接剂的催化剂层。该Ag-Cu催化剂具有枝晶状形貌,并且为Ag,Cu两相分离的双金属纳米材料。制备过程中,前驱体溶液CuSO_4和AgNO_3的浓度对Ag-Cu纳米材料的形貌有较大影响。经实验证明,在0.3 M CuSO_4溶液中置换2 h,再在10 mM AgNO_3溶液中置换120 s的条件下,Ag-Cu纳米材料为多层结构且枝晶形貌生长完整。电化学测试表明Ag-Cu双金属纳米催化剂催化氧还原的过程为4e~-路径。催化活性是纯Ag催化剂的2倍。以无碳、无粘接剂的Ag-Cu双金属纳米枝晶催化剂作为空气阴极,一次锌空气电池在20mA cm~(-2)电流密度下的放电电压为1.11 V。电池比容量和比功率密度分别为572mAh g~(-1)和641 mWh g~(-1)。可充锌空气电池的往复循环效率为53.9%。(2)电化学沉积法制备具有部分固溶的Ag-Cu纳米合金催化剂。通过改变前驱体溶液中Ag与Cu离子的摩尔比,制备了不同Cu含量的Ag-Cu纳米合金。通过氧还原活性的测试结果,得出提高Ag-Cu纳米合金催化活性的有效Cu含量为17%-40%。Ag-Cu纳米合金的催化活性为纯Ag的2.5倍。合金化后的Ag-Cu纳米材料具有较高的抗氧化性。以无碳、无粘接剂的Ag-Cu纳米合金催化剂作为空气阴极,一次锌空气电池在20 mA cm~(-2)电流密度下的放电电压为1.18 V。可充锌空气电池的往复循环效率为56.4%。且Ag-Cu纳米合金在锌空气电池中具有较好的抗CO_2中毒性。
[Abstract]:As an efficient and clean new energy technology, metal air battery has received more and more attention. The study of electrocatalysts for oxygen reduction has always been a hot issue in metal air batteries. In order to improve the catalytic activity of oxygen reduction reaction, increase the stability of catalyst and reduce the cost of catalyst, the study of Ag based catalyst is of great significance. The main research content of this paper is the catalytic activity of Ag-Cu nano-catalyst. In this paper, Ag-Cu bimetallic dendrites and Ag-Cu nanoalloys were prepared by Galvani substitution reaction and electrochemical deposition, respectively. The catalytic activity of Ag-Cu catalyst for oxygen reduction reaction was measured by electrochemical method, and the mechanism of improving the catalytic activity of oxygen reduction reaction with Ag-Cu nano-catalyst was studied by physical characterization. The main experimental conclusions of this paper are as follows: (1) Ag-Cu catalyst was prepared by Galvani substitution reaction. Ag-Cu catalyst was directly supported on the foam nickel collector to form a carbon-free and non-adhesive catalyst layer. The Ag-Cu catalyst has dendritic morphology and is a bimetallic nanomaterials with Ag,Cu two-phase separation. In the preparation process, the concentration of CuSO_4 and AgNO_3 in precursor solution has a great influence on the morphology of Ag-Cu nanomaterials. The experimental results show that when the Ag-Cu nanomaterials are replaced in 0.3M CuSO_4 solution for 2 h and then in 10 mM AgNO_3 solution for 120s, the Ag-Cu nanomaterials are multilayered and the dendritic morphology is complete. Electrochemical tests show that the process of oxygen reduction catalyzed by Ag-Cu bimetallic nanocatalyst is 4e path. The catalytic activity is twice as high as that of pure Ag catalyst. The discharge voltage of primary zinc air battery at 20mA cm~ (- 2) current density is 1.11 V. using Ag-Cu bimetallic nano-dendritic catalyst without carbon and adhesive as air cathode. The specific capacity and specific power density of the cell are 572mAh g ~ (- 1) and 641 mWh g ~ (- 1), respectively. The reciprocating cycle efficiency of rechargeable zinc air battery is 53.9%. (2) Ag-Cu nano-alloy catalyst with partial solid solution was prepared by electrochemical deposition. By changing the molar ratio of Ag to Cu ions in precursor solution, Ag-Cu nano-alloys with different Cu contents were prepared. Through the test results of oxygen reduction activity, it is concluded that the effective Cu content to improve the catalytic activity of Ag-Cu nano-alloy is 2.5 times of that of 17%-40%.Ag-Cu nano-alloy, which is 2.5 times of that of pure Ag. The alloyed Ag-Cu nanomaterials have high oxidation resistance. Using carbon-free and non-adhesive Ag-Cu nanoalloy catalyst as air cathode, the discharge voltage of primary zinc air battery at 20 mA cm~ (- 2) current density is 1.18 V. The reciprocating cycle efficiency of rechargeable zinc air battery is 56.4%. Ag-Cu nano-alloy has good anti-CO_2 toxicity in zinc-air battery.
【学位授予单位】：西北工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ426;TM911.41

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