多元醇体系过渡金属氧化物的结构调控及气敏、催化性能研究
发布时间：2018-11-26 10:45
【摘要】：材料是人类赖以生存和发展的物质基础，随着生产的高速发展以及由此带来的环境、能源问题的出现，新材料发展的重点已从结构材料转向功能材料。过渡金属氧化物，尤其是第四周期过渡金属氧化物，它们以其独特的化学、物理性质在气体传感、光电器件、电化学储能以及催化等领域都发挥着无可替代的作用。近年来，纳米科技的快速发展为功能材料的深入研究和材料微观结构的设计注入了新的元素，人们越发意识到功能材料的结构与功能之间存在着密切的联系。为了实现材料功能优化的目标，人们主要通过掺杂或复合来实现材料的组成调控，通过设计合成多孔结构、多级结构、活性晶面暴露以及纳米化等结构形态来实现材料微观结构的调控。本论文以第四周期过渡金属（Co、Ni、Cu和Zn）的氧化物为研究对象，以多元醇为反应体系，以优化这类氧化物材料的气体传感和催化水氧化反应性能为目标，系统地开展了相应材料的化学组成和微观结构调控研究。 本论文主要包括以下内容： 一、利用水和乙二醇混合溶剂的方法成功制备了多孔Cu2O/CuO立方体复合材料。在前驱体形成过程中，乙二醇既作溶剂，，也作还原剂，致使获得的前驱体中存在两种价态的铜。通过控制煅烧处理温度，可以控制产物Cu2O/CuO复合材料中CuO与Cu2O比例，而有机成分的分解及气体的生成则进一步导致多孔结构的形成。该复合材料对丙酮气体有很好的响应，350oC煅烧后得到的复合材料对丙酮气体的敏感性能最好，且明显优于商业CuO。当丙酮浓度为500ppm时，其响应值是商业CuO的4.3倍。进一步通过TPD测试手段验证了材料与不同气体之间的相互作用，从而解释了复合材料气敏选择性的本质原因。 二、同样采用水和乙二醇的混合溶剂，我们制备出由多孔纳米片组装形成的CdO/ZnO微球。研究发现元素Cd、Zn和O在微球中是均匀分布的，而且通过高分辨透射电镜可以清晰地观察到CdO和ZnO的界面。我们详细研究了该材料对乙醇的敏感特性，发现CdO的引入显著提高了ZnO材料对乙醇的响应程度，当Cd：Zn=7.5：100时，响应值最高，是单一ZnO材料的7倍，而且检测极限达到了0.5ppm，优于商业ZnO的2ppm。我们认为CdO促进ZnO气敏性能提高的原因在于CdO拥有大量的氧空穴，有利于氧分子在复合材料表面的吸附，增加了材料表面吸附氧的数量。另外CdO的低电阻特性促使电子易于传输，有利于检测到电阻变化。 三、采用溶剂热方法，在甘油、异丙醇混合溶剂中合成镍甘油盐微球，然后将镍甘油盐和硫酸亚铁混合，在水热条件下合成了高比表面积的Ni-Fe LDH材料，这些LDH材料表现出优异的电催化水氧化性能，其中，当Fe：Ni=0.52：1（ICP测试得到）时，性能最优，电流密度为10mA/cm2，过电势仅为344mV。所得材料的比表面积高，表面的活性位点多，并且多孔结构有利于电子和物质的传输，对催化水氧化反应活性的提高有积极作用。更重要的是Fe3+取代Ni(OH)2中的Ni2+形成LDH结构，Fe拥有更高的结合能，有利于电催化水氧化反应进行。我们认为，该合成思路可以扩展到其它具有不同组成和高比表面LDH材料的制备。 四、首先通过溶剂热方法合成了1，3丙二醇钴前驱体，经过煅烧该前驱体合成出多孔核壳的Co3O4八面体材料，其构筑单元为5nm的纳米粒子，且该材料比表面积高达190m2/g。我们对该材料在“光敏化剂-过硫酸盐”体系下进行了光催化水氧化性能的测试，发现其产氧速率可以达到~211.5μmol g-1min-1，约是商业Co3O4催化活性的18倍。由于缓冲溶液中的Na2SiF6发生水解，生成的氧化硅覆盖在Co3O4材料表面，减少了催化材料的活性位点，因此该材料经过长时间催化反应后，活性会有所下降，这表明该反应体系还需要进一步完善。
[Abstract]:The material is the material base of human existence and development. With the high-speed development of production and the environment and energy problems brought by it, the development of new materials has shifted from the structural material to the functional material. The transition metal oxides, especially the fourth periodic transition metal oxides, play an irreplaceable role in the fields of gas sensing, photoelectric devices, electrochemical energy storage and catalysis in their unique chemical and physical properties. In recent years, the rapid development of nano-technology has injected new elements into the research of functional materials and the design of the micro-structure of materials, and people have become more aware of the close relationship between the structure and function of the functional materials. In order to achieve the objective of material function optimization, the composition regulation of the material is mainly realized by doping or compounding, and the micro-structure of the material can be controlled by designing a structure such as a synthetic porous structure, a multi-stage structure, an active crystal face exposure and a nano-chemical structure. In this paper, the oxide of the transition metals (Co, Ni, Cu and Zn) in the fourth period was used as the research object, and the polyol was used as the reaction system to optimize the gas sensing and catalytic water oxidation reaction performance of the class of oxide materials. The chemical composition and micro-structure control of the corresponding materials are systematically carried out. The thesis mainly includes the following Content: 1. The porous Cu2O/ CuO cube was successfully prepared by the method of water and glycol mixed solvent. in that proces of the formation of the precursor, ethylene glycol is both a solvent and a reducing agent, so that the obtained precursor is present in two The ratio of CuO to Cu2O in the product Cu2O/ CuO composite can be controlled by controlling the temperature of the sintering treatment, and the decomposition of the organic components and the formation of the gas further lead to the porous. The composite material has good response to the acetone gas, Commercial CuO. The response value is commercial CuO when the acetone concentration is 500ppm and the interaction between the material and the different gases is further verified by the TPD test method, so that the gas-sensitive selectivity of the composite material is explained. the essential reason for this is that, in the same way, a mixed solvent of water and ethylene glycol is used, and the C formed by the assembly of the porous nanosheets is prepared. The results show that the elements Cd, Zn and O are uniformly distributed in the microball, and the Cd, Zn and O can be clearly observed through the high-resolution transmission electron microscope. The sensitivity of the material to ethanol was studied in detail. It was found that the introduction of CdO significantly improved the response of the ZnO material to the ethanol. When the Cd: Zn = 7.5: 100, the response value was the highest, which was 7 times that of the single ZnO material, and the detection limit reached 0. 5ppm, which was superior to the commercial. The reason for the improvement of the performance of CdO is that the CdO has a large number of oxygen holes, which is beneficial to the adsorption of the oxygen molecules on the surface of the composite material and the increase of the material. The number of oxygen adsorbed on the surface. The low resistance properties of the other CdO contribute to the easy transfer of electrons, in that method, a nickel-glycerol salt micro-ball is synthesized in a mixed solvent of glycerol and isopropanol by a solvent heat method, then the nickel-glycerol salt and the ferrous sulfate are mixed, and the Ni-Fe LDH material with high specific surface area is synthesized under the hydrothermal condition, and the LDH material has excellent performance Electrocatalytic water oxidation performance, in which, when Fe: Ni = 0.52: 1 (obtained by ICP test), the performance is optimal, and the current density is 10mA/ cm2 and the overpotential is only 344mV. the obtained material has a high specific surface area and a plurality of active sites on the surface, and the porous structure is beneficial to the transmission of electrons and materials, and the oxidation of the catalytic water It is more important to replace the Ni2 + in the Ni (OH) 2 to form the LDH structure, and the Fe has a higher binding energy. in that oxidation reaction of electrocatalytic wat, we think that the synthetic idea can be extended to other different composition and high The preparation method of the specific surface LDH material comprises the following steps of: firstly, synthesizing a 1, 3-propylene glycol cobalt precursor by a solvent thermal method, The surface area of the material is higher than 190m2/ g. The test of the photocatalytic water oxidation performance of the material under the 鈥減hotosensitizing agent-persulfate鈥
本文编号：2358340
[Abstract]:The material is the material base of human existence and development. With the high-speed development of production and the environment and energy problems brought by it, the development of new materials has shifted from the structural material to the functional material. The transition metal oxides, especially the fourth periodic transition metal oxides, play an irreplaceable role in the fields of gas sensing, photoelectric devices, electrochemical energy storage and catalysis in their unique chemical and physical properties. In recent years, the rapid development of nano-technology has injected new elements into the research of functional materials and the design of the micro-structure of materials, and people have become more aware of the close relationship between the structure and function of the functional materials. In order to achieve the objective of material function optimization, the composition regulation of the material is mainly realized by doping or compounding, and the micro-structure of the material can be controlled by designing a structure such as a synthetic porous structure, a multi-stage structure, an active crystal face exposure and a nano-chemical structure. In this paper, the oxide of the transition metals (Co, Ni, Cu and Zn) in the fourth period was used as the research object, and the polyol was used as the reaction system to optimize the gas sensing and catalytic water oxidation reaction performance of the class of oxide materials. The chemical composition and micro-structure control of the corresponding materials are systematically carried out. The thesis mainly includes the following Content: 1. The porous Cu2O/ CuO cube was successfully prepared by the method of water and glycol mixed solvent. in that proces of the formation of the precursor, ethylene glycol is both a solvent and a reducing agent, so that the obtained precursor is present in two The ratio of CuO to Cu2O in the product Cu2O/ CuO composite can be controlled by controlling the temperature of the sintering treatment, and the decomposition of the organic components and the formation of the gas further lead to the porous. The composite material has good response to the acetone gas, Commercial CuO. The response value is commercial CuO when the acetone concentration is 500ppm and the interaction between the material and the different gases is further verified by the TPD test method, so that the gas-sensitive selectivity of the composite material is explained. the essential reason for this is that, in the same way, a mixed solvent of water and ethylene glycol is used, and the C formed by the assembly of the porous nanosheets is prepared. The results show that the elements Cd, Zn and O are uniformly distributed in the microball, and the Cd, Zn and O can be clearly observed through the high-resolution transmission electron microscope. The sensitivity of the material to ethanol was studied in detail. It was found that the introduction of CdO significantly improved the response of the ZnO material to the ethanol. When the Cd: Zn = 7.5: 100, the response value was the highest, which was 7 times that of the single ZnO material, and the detection limit reached 0. 5ppm, which was superior to the commercial. The reason for the improvement of the performance of CdO is that the CdO has a large number of oxygen holes, which is beneficial to the adsorption of the oxygen molecules on the surface of the composite material and the increase of the material. The number of oxygen adsorbed on the surface. The low resistance properties of the other CdO contribute to the easy transfer of electrons, in that method, a nickel-glycerol salt micro-ball is synthesized in a mixed solvent of glycerol and isopropanol by a solvent heat method, then the nickel-glycerol salt and the ferrous sulfate are mixed, and the Ni-Fe LDH material with high specific surface area is synthesized under the hydrothermal condition, and the LDH material has excellent performance Electrocatalytic water oxidation performance, in which, when Fe: Ni = 0.52: 1 (obtained by ICP test), the performance is optimal, and the current density is 10mA/ cm2 and the overpotential is only 344mV. the obtained material has a high specific surface area and a plurality of active sites on the surface, and the porous structure is beneficial to the transmission of electrons and materials, and the oxidation of the catalytic water It is more important to replace the Ni2 + in the Ni (OH) 2 to form the LDH structure, and the Fe has a higher binding energy. in that oxidation reaction of electrocatalytic wat, we think that the synthetic idea can be extended to other different composition and high The preparation method of the specific surface LDH material comprises the following steps of: firstly, synthesizing a 1, 3-propylene glycol cobalt precursor by a solvent thermal method, The surface area of the material is higher than 190m2/ g. The test of the photocatalytic water oxidation performance of the material under the 鈥減hotosensitizing agent-persulfate鈥
本文编号：2358340
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