稀土掺杂氧化锌及羟基氧化铁复合材料催化机制研究

Photocatalysis technology based on TiO2 has provided an effective and promising means for sterilization and remediation of other environmental pollutants in water. However, its application for environmental protection still remains on the laboratory stage, mainly due to low efficiency in photoenergy utiliziation. A series of Nano ZnO-TiO2 composite materials and ferric hydroxide (FeOOH) composite materials have been studied as a photocatalyst. Up to know, rare publications reported the photocatalytic mechanism of both composite materials.Recently, we found that doping of rare earth ions (such as La, Ce, Er，et al) is able to increase the photocatalytic efficiency of ZnO-TiO2 and FeOOH composite materials. In order to explore the underlying catalytic mechanisms, we plan to synthesize the RE doped ZnO-TiO2 and FeOOH nano-photocatalyst using different methods, followed by efficiency evaluation of photocatalytic degradation of pharmaceutical wastewater solution and bacteria under different light source. The prepared particles will be characterized using XRD, HRTEM, UV-Vis and XPS, which will demonstrate the effect of doping amount, sintering temperature and carrier performance on the crystal morphology and the consequent photocatalytic activity. Through optimizing the preparation conditions, we aim to expand the range of effective absorption wavelength, improve photocatalytic efficiency and stability of ZnO-TiO2 and ZnO-FeOOH composite materials. In addition, considering the potential value of these composites in different supported materials, we also plan to investigate the effect of different supported materials on the crystal structure and photocatalytic ability of these composites through BET and Uv-vis methods. As will further enrich our understanding of the mechanisms underlying the impact of different supported materials on nano-composites. This project will not noly provide the optimal preparation conditions for ZnO-TiO2 and ZnO-FeOOH composites, also will throw light on the catalytic degradation mechanisms. Finally, this project is expected to establish new theoretical basis for further material modification and application in the future.

以TiO2为代表的半导体光催化氧化技术已在环境治理领域取得了较大的成效，但该体系现有效率还难以满足实际应用的需求。目前有关ZnO和FeOOH半导体光催化的研究较少，反应机理尚不清楚。我们近期研究发现，掺杂稀土离子后这两类复合材料光催化降解效率明显增加。申请者计划制备掺杂稀土离子的ZnO-TiO2纳米复合材料及羟基氧化铁复合材料，以制药废水和革兰氏代表菌为降解目标物检验光催化活性。研究稀土离子掺杂对光催化材料结构的影响，晶格结构变化与光催化活性的相关性；优化制备条件以扩展纳米复合材料有效吸收光波长范围，提高其光催化氧化能力和材料稳定性。讨论不同载体对复合材料的作用机制；研究结果不仅将确定氧化锌纳米复合材料及羟基氧化铁复合材料最优制备条件，同时有望全面揭示其催化降解机制，从而为后期进一步的材料改性和实际应用奠定理论基础。

随着工业与城市的发展，环境污染问题变得日益突出，传统方法难以有效解决这些问题。以纳米半导体氧化物为催化剂的多相光催化是一种高效、清洁的环境污染治理技术，已成为近年来国际上最为活跃的研究领域之一。本项目按计划开展了相关材料的制备、表征及性能研究的工作。制备了具有高效稳定的ZnO-TiO2，稀土掺杂ZnO及羟基氧化铁复合材料。表征分析了不同反应条件对催化剂微晶微观形貌的影响。探究了复合材料晶相调控机制及界面结构机理，进一步阐明了材料的微观结构影响催化性能的机制。通过研究不同制备条件下的催化材料的形貌与其吸附、催化性能的构效关系，深层次研究了ZnO、羟基氧化铁等复合材料的表面修饰状态与其光催化性能的表面电子转移之间的相互关系，探究了表面修饰状态与光催化的界面作用机制。研究表明，稀土元素的掺入使催化剂比表面积、孔隙率显著增加，加大了水中有机物与催化剂的接触机会，增加了光催化效率。采用液相合成法制备了ZnO量子点，采用表面修饰剂和不同元素掺杂对ZnO量子点进行表面修饰。表面修饰ZnO量子点时，并未改变ZnO量子点的晶体构型和结构，只是对其表面缺陷进行一定程度改善，使其团聚现象减少，制备的ZnO量子点具有良好的的光催化活性。采用模板调控α-Fe2O3的制备表征及吸附催化性能研究，得到不同制备条件下模板调控的α-Fe2O3吸附、光催化效果，揭示了纳米α-Fe2O3@C的可控制备及其对染料的强化吸收作用。同时，探究了Fe2O3对Ag-TiO2表面等离子体与二氧化钛形貌调控协同光催化作用机制，为揭示Fe2O3构效关系的理论研究及基础研究提供了指导。基于本项目，课题组发表国内外论文25篇,申报2项专利。项目成果对ZnO和 Fe2O3纳米材料的控制合成、结构性能调控、构效关系阐明具有重要意义。