催化学报

催化学报 ›› 2019, Vol. 40 ›› Issue (3): 343-351.DOI: 10.1016/S1872-2067(18)63157-2

• 论文 • 上一篇    下一篇

Ni纳米粒子作为电子转移剂和NiSx作为产氢界面活性位协同增强TiO2光催化制氢性能

王苹a, 徐顺秋a, 陈峰a, 余火根a,b   

  1. a 武汉理工大学化学化工与生命科学学院化学系, 湖北武汉 430070;
    b 武汉理工大学硅酸盐建筑材料国家重点实验室, 湖北武汉 430070
  • 收稿日期:2018-08-02 修回日期:2018-08-24 出版日期:2019-03-18 发布日期:2019-02-22
  • 通讯作者: 余火根
  • 基金资助:

    国家自然科学基金（21477094）；中央高校基本科研业务费专项基金（WUT2017IB002）.

Ni nanoparticles as electron-transfer mediators and NiSx as interfacial active sites for coordinative enhancement of H2-evolution performance of TiO2

Ping Wanga, Shunqiu Xua, Feng Chena, Huogen Yua,b   

  1. a Department of Chemistry, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, Hubei, China;
    b State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, Hubei, China
  • Received:2018-08-02 Revised:2018-08-24 Online:2019-03-18 Published:2019-02-22
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21477094) and the Fundamental Research Funds for the Central Universities (WUT 2017IB002).

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摘要：

作为一种传统的半导体光催化材料，TiO2因具有低价易得、无毒性及稳定性好等优势而一直受到研究者的关注.理论上，TiO2的能带结构可满足分解水制氢的条件.然而，研究发现TiO2本身的光催化制氢性能较低，主要是由于TiO2被光激发后生成的电子和空穴尚未到达材料表面参与反应，就在其体相内发生复合，导致电子参与有效光催化制氢反应的几率较低.近年来，为提高TiO2的制氢性能，研究者主要通过半导体耦合、元素掺杂、形貌调控和助剂修饰等方式对TiO2进行改性.其中，助剂表面修饰由于用量少、条件温和并且对主体材料结构影响很小而成为一种常见和有效的改性手段.最常用的电子助剂是贵金属如Au，Ag，Pt和Pd.当TiO2表面沉积微量的贵金属纳米粒子时，导带上的光生电子被贵金属捕获并迅速转移，将H+在贵金属表面发生界面还原反应生成H2，从而有效提高了制氢效率.除了贵金属电子助剂外，还有一些价格较低、产量丰富的非贵金属如Co，Cu，Ni和Bi等也可以作为电子助剂应用于光催化制氢，在提高制氢性能的同时也降低了光催化剂的成本.但在大多数情况下，这些金属材料（除贵金属Pt以外）本身都不能作为有效的界面催化活性位点，表现出较低的界面析氢速率，导致金属-半导体光催化材料的产氢活性低.因此，进一步对金属表面进行改性、增加界面催化活性位点、促进其界面产氢催化反应，对于提高金属-半导体光催化材料的制氢性能非常重要.
在金属作为电子传输介质修饰半导体材料的制氢过程中，电子传输介质快速转移光生电子和有效捕获溶液中的H+直接进行界面催化还原反应生成H2这两个步骤都十分关键.在制备金属-半导体光催化材料时，对于通常的金属材料本身都不能作为界面催化活性位点、缺乏有效的界面产氢活性位点的问题，可通过在金属表面进一步修饰作为界面催化活性位点的基团或离子来解决.本文采用先将Ni纳米粒子光沉积在TiO2表面、再在水热条件下在Ni纳米粒子表面生成NiSx的两步法合成了以Ni作为电子转移介质、以NiSx作为界面催化活性位点共修饰的高效TiO2光催化剂（称为TiO2/Ni-NiSx）.研究结果表明，优化后的TiO2/Ni-NiSx光催化的最高制氢速率（223.74 μmol h-1）分别是纯TiO2，TiO2/Ni和TiO2/NiSx样品的22.2，8.0和2.2倍.性能增强的原因是Ni纳米粒子作为电子传输体、NiSx作为界面催化活性位点同时提高了光生电子的转移速率和界面催化反应速率，即Ni和NiSx两者协同作用增强了TiO2光催化制氢性能.这种非贵金属助剂和界面活性位点协同作用的方法为设计高制氢性能催化剂提供了新的思路，并有望在光催化领域得到应用.

关键词: 二氧化钛, 电子转移剂, 界面活性位, 协同作用, 光催化制氢

Abstract:

The development of efficient photocatalytic H2-evolution materials requires both rapid electron transfer and an effective interfacial catalysis reaction for H2 production. In addition to the well-known noble metals, low-cost and earth-abundant non-noble metals can also act as electron-transfer mediators to modify photocatalysts. However, as almost all non-noble metals lack the interfacial catalytic active sites required for the H2-evolution reaction, the enhancement of the photocatalytic performance is limited. Therefore, the development of new interfacial active sites on metal-modified photocatalysts is of considerable importance. In this study, to enhance the photocatalytic evolution of H2 by Ni-modified TiO2, the formation of NiSx as interfacial active sites was promoted on the surface of Ni nanoparticles. Specifically, the co-modified TiO2/Ni-NiSx photocatalysts were prepared via a two-step process involving the photoinduced deposition of Ni on the TiO2 surface and the subsequent formation of NiSx on the Ni surface by a hydrothermal reaction method. It was found that the TiO2/Ni-NiSx photocatalysts exhibited enhanced photocatalytic H2-evolution activity. In particular, TiO2/Ni-NiSx(30%) showed the highest photocatalytic rate (223.74 μmol h-1), which was greater than those of TiO2, TiO2/Ni, and TiO2/NiSx by factors of 22.2, 8.0, and 2.2, respectively. The improved H2-evolution performance of TiO2/Ni-NiSx could be attributed to the excellent synergistic effect of Ni and NiSx, where Ni nanoparticles function as effective mediators to transfer electrons from the TiO2 surface and NiSx serves as interfacial active sites to capture H+ ions from solution and promote the interfacial H2-evolution reaction. The synergistic effect of the non-noble metal cocatalyst and the interfacial active sites may provide new insights for the design of highly efficient photocatalytic materials.

Key words: Titania, Electron-transfer mediator, Interfacial active site, Synergistic effect, Photocatalyic H2 evolution