催化学报

催化学报 ›› 2019, Vol. 40 ›› Issue (3): 390-402.DOI: 10.1016/S1872-2067(18)63173-0

• 论文 • 上一篇    下一篇

可控设计Zn-Ni-P修饰g-C3N4催化剂光催化产氢性能

李彦兵a,b, 靳治良a,b, 张利君a,b, 樊凯a,b   

  1. a 北方民族大学化学与化学工程学院, 宁夏银川 750021;
    b 北方民族大学国家民委化工技术基础重点实验室, 宁夏银川 750021
  • 收稿日期:2018-08-09 修回日期:2018-09-20 出版日期:2019-03-18 发布日期:2019-02-22
  • 通讯作者: 靳治良
  • 基金资助:

    国家自然科学基金（21862002，41663012）；北方民族大学创新团队项目（YCX18082）；北方民族大学科研项目（2016HG-KY06）.

Controllable design of Zn-Ni-P on g-C3N4 for efficient photocatalytic hydrogen production

Yanbing Lia,b, Zhiliang Jina,b, Lijun Zhanga,b, Kai Fana,b   

  1. a School of Chemistry and Chemical Engineering, North Minzu University, Yinchuan 750021, Ningxia, China;
    b Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, Ningxia, China
  • Received:2018-08-09 Revised:2018-09-20 Online:2019-03-18 Published:2019-02-22
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21862002, 41663012), the Innovation Team Project of North Minzu University (YCX18082), and the Scientific Research Project of North Minzu University (2016 HG-KY 06).

PDF

1072

摘要：

光催化分解水制氢是应对能源危机和环境污染问题的途径之一，也是实现太阳能转化和储存的有效方法.其中，应用层面的一个关键制约因素是高效光催化剂的开发和制氢反应体系的构建，理论层面的一个关键科学问题是光生电子-空穴的高效分离及光生电子定向迁移，这两个层面的问题构成当前光催化分解水制氢研究的重大挑战.因此，稳定、高效催化剂的制备成为光催化领域重要的研究目标.
类石墨烯氮化碳（g-C3N4）的结构与石墨相似，其层与层之间的范德华力使其具有良好的热稳定性和化学稳定性.g-C3N4是一种聚合物非金属半导体，由于具有与碳材料相似的层状堆积结构和sp2杂化的π共轭电子能带结构，因此被认为是最有可能代替碳材料用于光催化分解水制氢的新型光催化材料.g-C3N4的室温禁带宽度为2.7 eV左右，其价带和导带的位置完全覆盖了水的氧化-还原电位，因此理论上g-C3N4不仅能够氧化水为氧气，而且能够将水还原产氢，从而表现出优良的光电特性，成为新型太阳能转换材料.然而，g-C3N4在展示了良好研究前景的同时也存在一些缺陷，如比表面积较小及稳定性差等，这制约了g-C3N4在光催化领域的应用.为此，通过各种化学修饰对g-C3N4进行改性以提高其光催化活性和稳定性成为一个重要的研究方向.
本文采用高温煅烧方法成功制备了Zn-Ni-P@g-C3N4催化剂.将一定量的g-C3N4、乙酸镍、乙酸锌和次亚磷酸钠均匀混合在一起并研磨成粉末，然后以3 ℃/min的速率升温至300 ℃并在此温度下保持2 h，自然冷却至室温后即得到Zn-Ni-P@g-C3N4催化剂，整个制备过程在氮气环境中进行.研究表明，在Zn与Ni摩尔比为1：3的Zn-Ni-P@g-C3N4催化剂上，当反应体系pH=10，在420 nm光照下反应5 h产氢量可达531.2 μmol，是纯g-C3N4上的54.7倍.20 h循环实验表明催化剂具有较好的光催化稳定性.对催化剂进行了XRD、TEM、SEM、XPS、N2吸附、UV-vis DRS、瞬态光电流、FT-IR、瞬态荧光和Mott-Schottk等一系列表征，证明Zn-Ni-P的参与有效调变了电荷传输机制.SEM表征表明，Zn-Ni-P@g-C3N4为均匀排列的小颗粒，与纯g-C3N4相比其结构发生了改变，在Zn-Ni-P@g-C3N4结构中未发现g-C3N4纳米片的存在，说明Zn-Ni-P和g-C3N4成功复合.在上述研究基础上推测了可能的反应机理.

关键词: Zn-Ni-P, g-C3N4, 产氢, 可控设计, 光催化剂

Abstract:

Synthesizing a stable and efficient photocatalyst has been the most important research goal up to now. Owing to the dominant performance of g-C3N4 (graphitized carbonitride), an ordered assemble of a composite photocatalyst, Zn-Ni-P@g-C3N4, was successfully designed and controllably prepared for highly efficient photocatalytic H2 evolution. The electron transport routes were successfully adjusted and the H2 evolution was greatly improved. The maximum amount of H2 evolved reached about 531.2 μmol for 5 h over Zn-Ni-P@g-C3N4 photocatalyst with a molar ratio of Zn to Ni of 1:3 under illumination of 5 W LED white light (wavelength 420 nm). The H2 evolution rate was 54.7 times higher than that over pure g-C3N4. Moreover, no obvious reduction in the photocatalytic activity was observed even after 4 cycles of H2 production for 5 h. This synergistically increased effect was confirmed through the results of characterizations such as XRD, TEM, SEM, XPS, N2 adsorption, UV-vis DRS, transient photocurrent, FT-IR, transient fluorescence, and Mott-Schottky studies. These studies showed that the Zn-Ni-P nanoparticles modified on g-C3N4 provide more active sites and improve the efficiency of photogenerated charge separation. In addition, the possible mechanism of photocatalytic H2 production is proposed.

Key words: Zn-Ni-P, g-C3N4, H2 production, Controllable design, Photocatalyst