摘 要

本论文采用光沉积法和低温煅烧法制备了电子助剂Ag和界面产氢活性位点Ag₂O共修饰的高效TiO₂光催化材料(简称TiO₂/Ag-Ag₂O)，测试了TiO₂/Ag-Ag₂O光催化剂的制氢性能，并提出了相应的光催化机理。本研究对设计和制备新型高效稳定的光催化制氢材料具有重要的指导意义。

论文主要研究了TiO₂/Ag-Ag₂O光催化剂的晶体结构、形貌特征和光学特性，以及相应的制氢机理和影响制氢性能的相关因素。

研究结果表明：相比于TiO₂和Ag电子助剂修饰的TiO₂，经Ag和Ag₂O共修饰的TiO₂表现出更高的光催化活性。其中煅烧温度为300^oC的TiO₂/Ag-Ag₂O光催化剂具有最高的制氢速率，达到了75.197 μmol h^-1，分别是TiO₂(3.585 μmol h^-1)和TiO₂/Ag(41.133 μmol h^-1)的21.0倍和1.8倍。Ag和Ag₂O共修饰增强TiO₂光催化制氢性能的机理是：在紫外光照射下，电子助剂Ag快速捕获和传输TiO₂产生的光生电子，Ag₂O作为界面产氢活性位点从溶液中捕获H 生成H₂，Ag和Ag₂O的协同作用加快了TiO₂上光生电子的转移和界面产氢反应速率，从而提高了TiO₂制氢性能。

本文的特色：针对作为电子助剂的金属纳米粒子不能提供有效的界面产氢活性位点，限制材料制氢性能的问题，本文在半单体/金属电子助剂光催化体系的基础之上，增加了Ag₂O充当界面产氢活性位点以促进光催化材料的界面析氢反应，进一步增强了TiO₂的制氢性能。

关键词：光催化制氢；TiO₂；金属电子助剂；界面产氢活性位点；协同作用

Abstract

In this paper, the highly efficient TiO₂ photocatalysts co-modified by Ag as electron cocatalysts and Ag₂O as interfacial catalytic active sites (referred to as TiO₂/Ag-Ag₂O) were synthesized via a two-step process including the initial photoinduced deposition of metallic Ag nanoparticles on the TiO₂ surface and the following in situ oxidation of partial Ag into Ag₂O by low-temperature calcination. The photocatalytic H₂-evolution performance of TiO₂/Ag-Ag₂O photocatalyst was tested and its photocatalytic mechanism was also proposed proposes. This research has important guiding significance for the design and synthesis of new and highly efficient photocatalytic H₂-evolution materials.

In this paper, the crystal structure, morphology features and optical properties of TiO₂/Ag-Ag₂O composite photocatalyst were mainly studied. Meanwhile the corresponding photocatalytic mechanism and the related factors affecting its photocatalytic H₂-evolution performance were also studied.

Photocatalytic experimental results indicated that the TiO₂/Ag-Ag₂O photocatalysts exhibited a significantly higher photocatalytic H₂-evolution activity than the pure TiO₂ and TiO₂/Ag. When calcination temperature was controlled at 300^oC, the highest H₂-evolution rate of the resultant TiO₂/Ag-Ag₂O reached 75.197 μmol h^-1, which was higher than that of the TiO₂ (3.585 μmol h^-1) and TiO₂/Ag (41.133 μmol h^-1) by a factor of 21.0 and 1.8 times, respectively. On the basis of the experimental results, a synergistic effect of Ag as electron cocatalysts and Ag₂O as interfacial catalytic active sites is proposed for the improved photocatalytic H₂-evolution activity, namely, the Ag nanoparticle functions as an effective electron transfer mediator for the steady capture and rapid transportation of photogenerated electrons from TiO₂ surface, while the Ag₂O serves as the interfacial catalytic active-site to effectively adsorb H ions from solution and promote the rapid H₂-evolution reaction for enhanced photocatalytic H₂-evolution performance of TiO₂.

Metal nanoparticles as electron cocatalysts can’t provide effective interfacial catalytic active sites for H₂-evolution reaction, which limits the properties of hydrogen production. Therefore, in this paper, on the basis of semiconductor/metal electron cocatalysts photocatalytic system, Ag₂O was added as interfacial catalytic active sites to promote the interfacial hydrogen evolution reaction, which further enhanced the photocatalytic H₂-evolution performance of TiO₂ materials.

Keywords：photocatalytic H₂ evolution；TiO₂；metal electron cocatalyst；interfacial catalytic active site；synergistic effect

目 录

第一章 绪论 1

1.1 光催化研究概述 1

1.1.1 前言 1

1.1.2 半导体光催化材料 1

1.2 TiO₂光催化制氢的研究现状 2

1.2.1 TiO₂光催化制氢机理 2

1.2.2 TiO₂光催化制氢性能增强方法 3

1.3 金属助剂修饰增强光催化制氢性能的研究现状 5

1.4 金属电子助剂和活性位点共修饰研究现状 5

1.6 本论文的研究意义及内容 7

第2章 实验部分 8

2.1实验试剂和仪器 8

2.1.1实验试剂 8

2.1.2实验仪器 8

2.2样品制备 8

2.2.1 TiO₂-C的制备 8

2.2.2 TiO₂/Ag的制备 8

2.2.3 TiO₂/Ag-Ag₂O的制备 9

2.3 样品表征 9

2.4 光催化制氢性能测试 10

2.4.1样品制氢速率测试 10

2.4.2样品循环性能测试 10

2.5电化学测试 10

第3章 结果与讨论 12

3.1 TiO₂/Ag-AgO₂的合成思路 12

3.2 TiO₂/Ag-AgO₂形貌和相结构分析 13

3.2.1 XRD表征结果 13

3.2.2 SEM与TEM表征结果 13

3.2.3 XPS表征结果 13

3.2.4 UV-Vis表征结果 16

3.3 TiO₂/Ag-AgO₂制氢性能与机理分析 17

3.3.1样品制氢速率与循环性能 17

3.3.2样品制氢机理 18

3.3.3电化学表征与荧光光谱 19

3.4 制备TiO₂/Ag-Ag₂O样品影响因素 21

第4章 结论与展望 23

4.1 结论 23

4.2 展望 23

致 谢 24

参考文献 25

本科期间相关的科研成果 28

第一章 绪论

1.1 光催化研究概述

1.1.1 前言

随着社会生产力的快速发展，现有能源已经无法满足人类社会不断增长的能源需求，能源短缺日益严重。同时，生产和消费各种化石能源引起了环境污染、温室效应等问题，严重危害了人类社会的生存和发展，已经成为世界关注的焦点问题。因此，在能源危机和环境污染的双重压力下，开发新型清洁能源成为各国科学家研究的首要任务^[1]。在各种新能源中，氢能因其储量大、来源广泛、产热高、清洁无污染等优点受到各国科学家的青睐，被认为是21世纪最具发展潜力的能源^[2]。目前获取氢能最常用的方法包括天然气及重油催化转化法、生物产氢法、煤炭气化法、水电解法等，但这些方法都存在成本高昂、使用化石能源或者污染环境等问题。在各类制备氢气的技术中，由Fujishima等人^[3]开创的半导体光催化分解水制氢技术具有利用太阳能、反应条件温和、操作简便、环境友好等优势。因此，光催化分解水制氢成为一项具有巨大应用潜力、较为理想的新型制氢技术，吸引着越来越多的科学研究者投身其中。

1.1.2 半导体光催化材料