凹凸棒土/g-C3N4/AgFeO2复合材料的制备及其光催化性能的研究

论文总字数：14949字

摘 要

本文以凹凸棒土（ATP）为基体，首先将g-C₃N₄薄层材料有效负载于其表面，构筑ATP/g-C₃N₄可见光催化剂；再通过原位沉淀法在其表面引入不同比例的AgFeO₂纳米颗粒，合成系列兼具磁分离特性和高效光催化活性的ATP/g-C₃N₄-AgFeO₂-Y% （Y=ATP/g-C₃N₄占复合材料的质量百分数）复合光催化剂。采用XRD、SEM、BET、UV-Vis和吸附实验表征其结构和物化性能，以酸性红为探针，研究其光催化性能。研究发现，纳米AgFeO₂颗粒分布均匀沉积在ATP/g-C₃N₄表面，没有明显的团聚现象；由于形成了II型异质结，ATP/g-C₃N₄-AgFeO₂-Y%具有比ATP/g-C₃N₄和AgFeO₂更优异的可见光光催化性能，而且随着ATP/g-C₃N₄的含量升高先增强而后下降；当Y=57%时复合材料的性能最佳，ATP/g-C₃N₄-AgFeO₂-57%对20mg/L的酸性红G（ARG）的降解率可达97.4%，循环4次使用后，降解率仍保持94.2%。通过自由基捕获实验研究了光催化反应机理，发现·O₂^-是光催化过程的主要活性物种。

关键词: 凹凸棒土，类石墨相氮化碳，铁酸银，可见光催化

Abstract：This article used attapulgite (ATP) as a matrix, and the g-C₃N₄ thin layer was firstly loaded on the surface to synthesize ATP/g-C₃N₄ visible light catalyst. Then, AgFeO₂ nanoparticles with different ration were hybridized to the surface of ATP/g-C₃N₄ by in-stiu precipitation method and the obtained products were marked as ATP/g-C₃N₄-AgFeO₂-Y%, where Y presented as the mass percentage of ATP/g-C₃N₄ in the ATP/g-C₃N₄-AgFeO₂ composite. SEM, BET, UV-Vis and adsorption experiments were used to characterize the structure and physicochemical properties. Acid red G was used as a probe to study its photocatalytic properties. It was found that the nano-AgFeO₂ particles were evenly distributed on the surface of ATP/g-C₃N₄ without obvious agglomeration. Under visible light irradiation, ATP/g-C₃N₄-AgFeO₂-Y% had better photocatalytic performance than that of ATP/g-C₃N₄ and AgFeO₂ because of formation of a type II heterojunction between g-C₃N₄ and AgFeO₂. Besides, the photocatalyic activity of ATP/g-C₃N₄-AgFeO₂-Y% enhanced with the increase content of ATP/g-C₃N₄ and decreased after a certain amount, and ATP/g-C₃N₄-AgFeO₂-57% is the best. The degradation rate of 20 mg/L acid red G (ARG) catalyzed by ATP/g-C₃N₄-AgFeO₂-57% was up to 97.4%, and after 4 cycles of use, the degradation rate remained at 94.2%. The photocatalytic reaction mechanism was studied on the basis of evaluating the photodegradation performance of the catalyst. It was found that ·O₂^- is the main active species of the photocatalytic process.

Key words: ATP, g-C₃N₄, Ag₂Fe₂O₄, Visible light photocatalysis

目 录

1 绪论 1

1.1 引言 1

1.2 对g-C₃N₄可见光催化剂的研究 1

1.3 凹凸棒土研究现状 1

1.4 尖晶石铁氧体的引入 2

1.5 本课题研究内容 3

2 实验部分 3

2.1 实验试剂与仪器 3

2.2 ATP/g-C₃N₄-AgFeO₂-Y%光催化剂的制备 4

2.3 光催化性能测试 4

2.4 表征仪器与方法 5

3 实验结果与讨论 5

3.1 结构与形貌分析 6

3.1.1 XRD谱图分析 6

3.1.2 红外谱图分析 6

3.1.3 扫描电镜图分析 7

3.1.4 N₂吸附-脱附曲线分析 9

3.1.5 紫外-可见漫反射光谱分析 9

3.2 ATP/g-C₃N₄-AgFeO₂-Y%光催化性能的研究 10

3.3 ATP/g-C₃N₄-AgFeO₂-57%光催化机理的探讨 13

结论 16

参考文献 17

致谢 19

1 绪论

1.1 引言

近年来，环境恶化和资源过度消耗是新时代我国发展进程中两大不可忽视的难题。太阳能作为一种我们熟知的清洁能源，已逐渐成为我们日常生活的重要组成部分，且其资源丰富，可以长久利用。但是太阳能存在分散性强、稳定性差、不易存储等缺点^[1]，而光催化技术可以直接将太阳能有效利用，通过光催化剂将有机污染物降解为CO₂、H₂O以及矿物酸或盐等物质，效率高、能耗低且无二次污染。其机理如图1^[2]所示。

目前，在处理废水和空气污染等方面，已应用到光催化技术。因为太阳能中可见光占比最高，所以开发高效的可见光光催化材料至关重要。现阶段，主流的光催化剂主要是无机半导体材料，可以分为金属硫化物、氧化物等^[2]。近年来，一种新型的全有机半导体聚合物——类石墨相氮化碳（g-C₃N₄）受到了广泛的关注。

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