基于过渡金属催化剂的合成设计及其水氧化性能的研究

发布时间：2018-05-05 00:16

本文选题：光催化水氧化 + 电催化水氧化　；参考：《兰州大学》2017年硕士论文

【摘要】：为了能够解决人类目前面临的严峻的能源危机问题和因化石燃料的燃烧导致的环境污染问题,科学家认为通过人工模拟光合作用进行水裂解制备氢气和氧气从而实现太阳能到化学能的转化过程是一项行之有效的解决方案。其中,水氧化过程动力学缓慢,成为水裂解研究的瓶颈,因此大量研究投入到开发高效,廉价,稳定的水氧化催化剂。第一过渡金属氧化物是一类极具潜力的水氧化催化剂,受到研究工作者的广泛关注。但随着对这类材料的探索,研究者将重点集中在机理的研究上,以便理论指导实践,进一步提高其催化活性,实现工业化。另一方面,过渡金属取代的多酸金属氧酸盐作为稳定的均相分子催化剂,在机理研究方面的潜力被研究者们广泛关注。因为它们具有全无机的配位结构,因而可以承受水氧化反应过程中的强氧化环境。Co、Ni、Cu等过渡金属原子由于受到缺位杂多酸配体的影响会表现出特有的物理化学性质。本文则主要在Co/Cu过渡金属氧化物作为光催化水氧化催化剂和电催化水氧化催化剂的开发方面展开了研究工作,对含Co,Cu,Ni,Mn,Zn的过渡金属取代的POM的光催化水氧化性能也做了初步探索。主要包括以下几个方面:1.合成、表征了一系列以MOF为牺牲模板剂的多孔Co_3O_4/Cu O中空多面体纳米笼复合材料,并优化了Co/Cu比例。在Visible-light/Ru(bpy)3~(2+)/Na_2S_2O_8光催化水氧化体系中,测试了上述材料的催化活性。研究结果发现,多孔Co_3O_4/Cu O中空多面体纳米笼具有异质结通过形成内在电场加强了电子空穴的分离,在光驱动水氧化中增强了光催化产氧活性。2.合成、表征了一系列具有相同形貌的多孔中空多面体纳米笼材料:Cu-ZIF-T(Cu_(0.2)Co_(2.8)O_4),Cu O/Co_3O_4和Co_3O_4,来探究不同修饰方法对于光催化、电催化产氧催化剂活性的影响。将Cu~(~(2+))掺杂到Co_3O_4晶格中的催化剂Cu-ZIF-400和将Cu O负载到Co_3O_4上的催化剂Cu O/Co_3O_4具有比Co_3O_4更好的电、光催化产氧性能。并且探索了不同煅烧温度对于催化剂Cu-ZIF-T活性的影响。3.合成、表征了一系列不同过渡金属取代的杂多酸盐水氧化催化剂[M_2(B-β-Si W_8O_(31))_2]16-(M=Cu~(~(2+))/Co~(2+)/Mn~(2+)/Ni~(2+)/Zn~(2+))。在Ru(bpy)3~(2+)/visible-light/Na_2S_2O_8光催化水氧化体系中,对上述各个POM的水氧化催化活性进行了研究。研究结果发现,不同的过渡金属取代的杂多酸具有不同的水氧化催化性能。
[Abstract]:In order to solve the serious energy crisis facing mankind and the environmental pollution caused by the burning of fossil fuels, Scientists believe that the conversion of solar energy to chemical energy by artificial simulation of photosynthesis to produce hydrogen and oxygen by water cracking is an effective solution. Among them, the kinetics of water oxidation process is slow, which becomes the bottleneck of water cracking research, so a lot of research is devoted to the development of efficient, cheap and stable water oxidation catalyst. The first transition metal oxide (TO) is a kind of water oxidation catalyst with great potential. However, with the exploration of this kind of materials, the researchers will focus on the study of mechanism, in order to guide the theory and practice, further improve its catalytic activity and realize industrialization. On the other hand, transition metal substituted polyoxometalate as a stable homogeneous molecular catalyst has attracted much attention in mechanism research. Because of their total inorganic coordination structure, they can withstand the strong oxidation environment during the water oxidation reaction. The transition metal atoms, such as Coannion Cu, exhibit unique physical and chemical properties due to the influence of the absence of heteropoly acid ligands. In this paper, the development of Co/Cu transition metal oxide as photocatalytic water oxidation catalyst and electrocatalytic water oxidation catalyst has been studied, and the photocatalytic water oxidation performance of transition metal substituted POM containing CoCU / NiMn-Mn-Zn has also been preliminarily explored. Mainly include the following aspects: 1. A series of porous Co_3O_4/Cu O hollow polyhedron nanocomposites with MOF as sacrificial template were synthesized and characterized. The Co/Cu ratio was optimized. The catalytic activity of the above mentioned materials was tested in the photocatalytic water oxidation system of Visible-light/Ru(bpy)3~(2 / Na _ 2s _ 2O _ 8. The results show that porous Co_3O_4/Cu O hollow polyhedron nanorages have heterojunctions which enhance the separation of electron holes through the formation of internal electric field and enhance the photocatalytic oxygen-producing activity of photocatalytic oxidation. A series of porous hollow polyhedron nanocages with the same morphology have been synthesized and characterized. The effects of different modification methods on the activity of photocatalytic and electrocatalytic oxygen-producing catalysts have been investigated. The catalyst Cu-ZIF-400 doped in Co_3O_4 lattice and Cu O/Co_3O_4 doped with CuO on Co_3O_4 have better electrocatalytic and photocatalytic oxygen-producing properties than Co_3O_4. The effect of calcination temperature on the Cu-ZIF-T activity of the catalyst was investigated. A series of heteropoly acid salt water oxidation catalysts with different transition metal substitutions have been synthesized and characterized. The results show that a series of different transition metal substituted heteropoly acid brine oxidation catalysts [M _ 2H _ 2B _ (- 尾 -Si W_8O_(31))_2)] 16-(M=Cu~(2 / Co ~ (2 / 2) / mn ~ (2 / N) / Ni ~ (2 / N) / Zn ~ (2 / O) ~ (2 / In the Ru(bpy)3~(2 / visible-light- / Na2S2O8 photocatalytic water oxidation system, the water oxidation catalytic activity of the above mentioned POM was studied. The results show that different transition metal substituted heteropoly acids have different catalytic properties of water oxidation.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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