摘 要

目前，半导体光催化技术以其低成本、工艺简单、低能耗、降解效率高的优点在降解污染物方面得到广泛关注。可见光光催化材料中，由于Ag₃PO₄具有禁带宽度普遍偏窄，易产生等离子共振效应等特点，使其在光催化降解有机物领域展现出美好的应用前景。研究发现，对Ag₃PO₄材料进行表面修饰能很好的提升其光催化性能和稳定性。

本论文以还原氧化石墨烯作为电子助剂和NiPi作为空穴助剂对Ag₃PO₄进行表面修饰来增强其光催化性能。实验采用两步法对Ag₃PO₄进行表面修饰，先后使用水热法与光沉积法分别将还原氧化石墨烯(rGO)与NiPi助剂负载到Ag₃PO₄上，得到NiPi-rGO/Ag₃PO₄复合光催化材料。探究了不同含量NiPi对rGO-Ag₃PO₄进行修饰后可见光下降解甲基橙的性能，通过对一、二、三元相样品进行甲基橙降解循环性能测试，研究样品的稳定性，最后用FESEM、XRD、UV-vis检测方式对样品进行表征。

研究结果表明，GO与Ag₃PO₄在180 ℃下水热24 h后得到的rGO/Ag₃PO₄光催化剂具有很好的光催化降解性能，其光催化速率常数是纯Ag₃PO₄速率常数(0.0289 min^-1)的2.50倍，当分别将质量分数为0.1 wt%、0.5 wt%、1 wt%、5 wt%、10 wt%的NiPi负载到rGO/Ag₃PO₄上后，其可见光催化速率常数是纯Ag₃PO₄速率常数(0.0289 min^-1)的2.50、5.04、4.91、5.05、8.65、3.16倍，表明以rGO 作为电子助剂与NiPi作为空穴助剂对Ag₃PO₄进行表面修饰能极大提高Ag₃PO₄光催化性能。Ag₃PO₄光催化性能得到提升的原因为复合材料经可见光照射后，rGO能加速光生电子的转移，NiPi能加速光生空穴的转移，协同抑制光生电子与光生空穴的复合，从而提升复合材料的光催化活性。

本论文的特色在于：提出了以两步法合成NiPi-rGO/Ag₃PO₄复合光催化剂的方法，探究了NiPi作为空穴助剂表面修饰Ag₃PO₄增强其光催化活性的可行性与性能，结果显示，NiPi-rGO/Ag₃PO₄复合光催化剂具有很高的可见光光催化性能，并证明了NiPi作为空穴助剂协同rGO表面改性Ag₃PO₄是一种简单易行的光催化剂表面改性方法。

关键词：Ag₃PO₄；还原氧化石墨烯；NiPi；表面修饰；可见光光催化性能

Abstract

At present, semiconductor photocatalytic technology is widely used in the degradation of pollutants because of its low cost, simple process, low energy consumption and high degradation efficiency. As one of the visible light photocatalyst materials, because of Ag₃PO₄ photocatalyst has the characteristics of narrow energy gap, and is easy to produce plasma resonance effect and so on, so that in the field of photocatalytic degradation of organic matter to show a bright future.. It was found that the surface modification aimed for Ag₃PO₄ could improve its photocatalytic performance and stability.

In this work, Ag₃PO₄ was modified by reduced grapheme oxide as an electron cocatalyst and NiPi as a hole cocatalyst to enhance its photocatalytic performance. I used a two-step method for surface modification to Ag₃PO₄. NiPi-rGO/Ag₃PO₄ composite photocatalyst was prepared by loading the reduced graphene oxide(rGO) on Ag₃PO₄ by hydrothermal method and photodeposition respectively. The degradation properties of methyl orange were investigated by the degradation of rGO/Ag₃PO₄ with different contents. The stability of the samples was studied by the cyclic performance testing of methyl orange degradation. The stability of the samples was studied by FESEM, XRD, UV-vis tests of the sample.

The results showed that rGO- Ag₃PO₄ obtained by hydrothermal treatment of GO and Ag₃PO₄ at 180 ℃ for 24 h had good photocatalytic degradation performance, its photocatalytic rate constant is 2.50 times the pure Ag₃PO₄ rate constant (0.0289 min^-1). When the rGO/Ag₃PO₄ particle was modified by the different NiPi contens such as 0.1wt%、0.5wt%、1wt%、5wt%、10wt%, their visible light catalytic rate constants were 5.04, 4.91, 0.5, 5.05, 8.65, 3.16 times,compared to the Ag₃PO₄(0.0289 min^-1). The results showed that the surface modification of Ag₃PO₄ with rGO as an electron cocatalyst and NiPi as a hole cocatalyst can greatly improve the photocatalytic performance of Ag₃PO₄.The photocatalytic performance of Ag₃PO₄ was improved, because of when the composite material under the visible light irradiation, rGO could accelerate the speed of transfer photogenerated electrons, NiPi could accelerate the speed of transfer photogenerated holes, synergistically inhibited the combination of photogenerated electrons and photogenerated holes, thereby enhanced the light catalytic activity of composite material.

In this paper, the method of synthesizing NiPi-rGO/Ag₃PO₄ composite photocatalyst by two-step method is proposed. The feasibility and properties of NiPi as a hole cocatalyst modified Ag₃PO₄ to enhance its photocatalytic activity are investigated. The results show that NiPi -rGO / Ag₃PO₄ composite photocatalyst has a high visible light photocatalytic performance, and proved that NiPi as a hole cocatalyst synergistic rGO surface modified Ag₃PO₄ is a simple and easy photocatalyst surface modification method.

Key words：Ag₃PO₄；reduced grapheme oxide；NiPi；surface modification；visible light photocatalytic performance

目 录

第1章 绪论 1

1.1 研究背景 1

1.2 光催化材料及光催化降解有机物机理 1

1.3 银类光催化剂研究进展 2

1.4 助剂修饰Ag₃PO₄提高光催化降解性能研究进展 3

1.4.1 形貌可控合成 3

1.4.2 半导体复合 4

1.4.3 表面助剂修饰 4

1.5 本论文的研究意义与主要内容 5

第2章 实验部分 7

2.1 实验试剂和仪器 7

2.1.1 实验试剂 7

2.1.2 实验仪器 7

2.2 实验样品的制备 8

2.2.1 Ag₃PO₄光催化剂的制备 8

2.2.2 rGO/Ag₃PO₄光催化剂的制备 9

2.2.3 NiPi –rGO/Ag₃PO₄光催化剂的制备 9

2.3 样品表征 10

2.4 样品光催化降解性能测试 10