【作者】 叶琳；

【导师】 孙少东； 崔杰；

【作者基本信息】 西安理工大学 ， 材料物理与化学， 2023， 硕士

【摘要】 氧化亚铜(Cu2O)作为一种典型的p型半导体材料,因具有可见光响应、低毒、制备工艺简单、无二次污染等优点被广泛应用于光催化领域。然而,光生载流子容易复合以及可见光谱响应范围窄等问题严重影响了 Cu2O的光催化性能。传统的C2O基复合光催化材料通常为type-Ⅱ型异质结构,由于该异质结构的氧化和还原反应均各自发生在价带和导带能级位置相对较低的半导体中,故而通常导致光催化活性降低。目前,构建具有高导带和价带电极电势的Z-scheme异质结构,被认为是改善可见光吸收和提高光生载流子分离与传输效率的有效途径。然而,对于结构新颖且性能优异的Z-scheme Cu2O基复合材料的相关研究报道较少,对其微观结构、物理化学性质的调控机理以及光催化性能的增强机制仍需深入探索研究。鉴于此,本文分别基于“Z-scheme机制”、“协同吸附-光催化效应”和“晶体-非晶体界面效应”策略来提升Cu2O复合光生载流子分离效率和可见光捕获能力,成功制备了ZnO/Cu2O花状纳米异质结构和晶体-非晶体Cu2O/Ti-Fe双金属层状氢氧化物(LDH)。结果表明:上述两种Z-scheme Cu2O基光催化材料可显著提升Cu2O的光生载流子分离效率和可见光吸收能力,有利于增加表面反应活性位点,深度优化了 Cu2O的光催化活性。本文的主要研究结果如下:(1)采用十六烷基三甲基溴化铵(CTAB)辅助液相还原法,成功构建了ZuO/Cu2O复合光催化材料。其在可见光辐照下对四环素(TC)的光降解结果表明:ZnO/Cu2O异质结构的光催化活性明显优于传统ZnO/Cu2O异质结构、纯ZnO和纯Cu2O,约为ZnO的2.9倍、Cu2O的2.2倍。这是因为ZnO/Cu2O异质结构较大的比表面积为反应提供了更多的吸附容量和活性位点,同时相比于纯光催化,在“协同吸附-光催化效应”作用下降解效率进一步提升。另外,形成的“Z-scheme机制”使光生电子和空穴均保留在较高的电位中发生反应,提升了氧化还原能力,促进了光生载流子分离。(2)采用牺牲Cu2O模板液相合成法,成功构建了Cu2O/Ti-Fe LDH 复合光催化材料。其在可见光辐照下对TC的光降解结果表明:Cu2O/Ti-Fe LDH的光降解效率分别是纯Cu2O纳米球和纯Ti-Fe LDH纳米片的5.2倍和2.2倍,并具有良好的循环稳定性。究其原因在于:非品Ti-Fe LDH纳米片较大的比表面积为反应提供了丰富的活性位点,同时在“晶体-非晶体界面效应”作用下有效促进了 Cu2O表面光生载流子分离。另外,形成的Z-scheme异质结构保留了高的氧化还原电位,更有利于提升光催化效率。更多还原

【Abstract】 As a typical p-type semiconductor material,cuprous oxide(Cu2O)has been widely used in the field of photocatalysis due to its visible light response,low toxicity,simple preparation process,and no secondary pollution.However,the photocatalytic performance of Cu2O is seriously affected by the problems of easy recombination of photocarriers and narrow response range of visible spectrum.Traditional cuprous oxide matrix composite photocatalytic materials are usually type-II heterogeneous structures.Because the oxidation and reduction reactions of the heterogeneous structures occur respectively in semiconductors with relatively low valence and conduction band levels,the photocatalytic activity is usually reduced.At present,the construction of Z-scheme heterogeneous structures with high conduction and valence band electrode potentials is considered to be an effective way to improve visible light absorption and the efficiency of photogenerated carrier separation and transport.However,there are few reports on the novel structure and excellent performance of Z-scheme Cu2O matrix composites,and further exploration is needed to investigate the mechanism of microstructure,physical and chemical properties of Cu2O matrix composites and the enhancement of photocatalytic properties.In view of this,this paper is based on the strategies of "Z-scheme mechanism","collaborative adsorptionphotocatalytic effect" and "crystal-amorphous interface effect" respectively to improve the photogenerated carrier separation efficiency and visible light capturing ability of Cu2O.ZnO/Cu2O floral nanostructures and crystalline/amorphous Cu2O/Ti-Fe layer metal hydroxides(LDH)have been prepared successfully.The results show that the two Z-scheme Cu2O based photocatalytic materials can significantly improve the photogenic carrier separation efficiency and visible light absorption capacity of Cu2O,which is conducive to increasing the surface reactive sites,and deeply optimize the photocatalytic activity of Cu2O.The main research results of this paper are as follows:(1)ZnO/Cu2O composite photocatalytic materials have been successfully constructed by hexadecyl trimethyl ammonium bromide(CTAB)assisted liquid phase reduction method.The photodegradation results of tetracycline(TC)under visible light irradiation show that the photocatalytic activity of ZnO/Cu2O heterostructures is obviously better than that of traditional ZnO/Cu2O heterostructures,pure ZnO and pure Cu2O,which is about 2.9 times of ZnO and 2.2 times of Cu2O.This is because the larger surface area of the ZnO/Cu2O heterostructure provides more adsorption capacity and active sites for the reaction.Meanwhile,compared with pure photocatalysis,the degradation efficiency of the "synergistic adsorption-photocatalysis effect" is further improved.In addition,the formation of the "Z-scheme mechanism" enables the photogenerated electrons and holes to remain at a higher potential for reaction,which improves the oxidation and reduction capacity and promotes the photogenerated carrier separation.(2)Cu2O/Ti-Fe LDH composite photocatalytic material was successfully constructed by liquid phase synthesis method sacrificing Cu2O template.The photodegradation results of TC under visible light irradiation show that the photodegradation activity of Cu2O/Ti-Fe LDH is 5.2 times and 2.2 times that of pure Cu2O nanospheres and pure Ti-Fe LDH nanosheets,respectively,and has good cyclic stability.The reason is that the large specific surface area of amorphous TiFe LDH nanosheets provides abundant active sites for the reaction,and effectively promotes the separation of Cu2O surface photogenerated carrier under the "crystal-amorphous interface effect".In addition,the formed Z-scheme heterostructures retain high oxidation and reduction potential,which is more conducive to improving the photocatalytic efficiency更多还原