物理化学学报 >> 2020, Vol. 36 >> Issue (3): 1901051.doi: 10.3866/PKU.WHXB201901051

所属专题： 光催化剂

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SiC/Pt/CdS纳米棒Z型异质结的制备及其高效光催化产氢性能

曹丹1,安华1,严孝清1,赵宇鑫1,杨贵东1,*(),梅辉2,*()   

  1. 1 西安交通大学化学工程与技术学院，西安交通大学-牛津大学催化国际联合实验室，西安 710049
    2 西北工业大学材料科学与工程学院，超高温结构复合材料重点实验室，西安 710072
  • 收稿日期:2019-01-22 录用日期:2019-03-28 发布日期:2019-04-01
  • 通讯作者: 杨贵东,梅辉 E-mail:guidongyang@xjtu.edu.cn;meihui@nwpu.edu.cn
  • 基金资助:
    the National Natural Science Foundation of China(U1862105);Natural Science Basic Research Plan in Shaanxi Province of China(2017JZ001);Natural Science Basic Research Plan in Shaanxi Province of China(2018KJXX-008);Key Research and Development Program of Shaanxi Province, China(2018ZDCXL-SF-02-04);Fundamental Research Funds for the Central Universities, China(cxtd2017004);K. C. Wong Education Foundation and Hong Kong, China

Fabrication of Z-Scheme Heterojunction of SiC/Pt/Cds Nanorod for Efficient Photocatalytic H2 Evolution

Dan Cao1,Hua An1,Xiaoqing Yan1,Yuxin Zhao1,Guidong Yang1,*(),Hui Mei2,*()   

  1. 1 XJTU-Oxford International Joint Laboratory for Catalysis, School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an 710049, P. R. China
    2 Science and Technology on Thermostructural Composite Materials Laboratory, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, P. R. China
  • Received:2019-01-22 Accepted:2019-03-28 Published:2019-04-01
  • Contact: Guidong Yang,Hui Mei E-mail:guidongyang@xjtu.edu.cn;meihui@nwpu.edu.cn
  • Supported by:
    国家自然科学基金(U1862105);陕西省自然科学基础研究计划(2017JZ001);陕西省自然科学基础研究计划(2018KJXX-008);陕西省重点研发计划(2018ZDCXL-SF-02-04);中央基本科研业务费(cxtd2017004);王宽诚教育基金会

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摘要：

本文采用简单的化学还原辅助水热法制备了一种新型SiC/Pt/CdS Z型异质结纳米棒，并将Pt纳米粒子锚定在SiC纳米棒与CdS纳米粒子的界面间，诱导电子-空穴对沿着Z型迁移路径进行转移。进行一系列的表征来分析该催化体系的结构，形貌和性能。X射线衍射(XRD)和X射线光电子能谱(XPS)结果表明，成功合成了具有较好晶体结构的光催化剂。通过透射电子显微镜证明，Pt纳米颗粒生长在SiC纳米棒和CdS纳米颗粒的界面间。UV-Vis漫反射光谱显示，所制备的Z-型异质结样品具有比原始CdS材料更宽的光吸收范围。光致发光光谱和瞬态光电流响应进一步证明具有最佳摩尔比的SiC/Pt/CdS纳米棒样品具有最高的电子-空穴对分离效率。通过控制SiC和CdS的摩尔比，可以有效地调节SiC/Pt纳米棒表面CdS的负载量，从而使得SiC/Pt/CdS纳米棒光催化剂达到最佳性能。当SiC : CdS = 5 : 1 (摩尔比)时可以达到最佳产氢性能，其最大析氢速率达到122.3 μmol∙h−1。此外，从扫描电子显微镜、XRD和XPS分析可以看出，经过三次循环测试后，SiC/Pt/CdS光催化剂的形貌和晶体结构均基本保持不变，表明SiC/Pt/CdS纳米复合材料在可见光下产氢时具有稳定的结构。通过选择性光沉积技术在光反应中同时进行Au纳米粒子的光还原沉积和Mn3O4纳米粒子光氧化沉积以证明电子-空穴对的Z-型转移机制。实验结果表明，CdS导带上的电子主要参与光催化过程中的还原反应，SiC价带上的空穴更容易发生氧化反应，其中，SiC的导带上的电子将与CdS价带上的空穴复合形成Z型传输路径。因此，提出了在光催化产氢过程中SiC/Pt/CdS纳米棒催化体系可能的Z-型电荷迁移路径来解释产氢活性的提高。该研究为基于SiC纳米棒的Z-型光催化体系的合成提供了新的策略。基于以上分析，SiC/Pt/CdS纳米复合材料具有高效、廉价、易于制备、结构稳定等优势，具有突出的商业应用前景。

关键词: 碳化硅, 纳米棒, SiC/Pt/CdS, 光催化剂, Z型异质结

Abstract:

In this study, a novel silicon carbide/platinum/cadmium sulfide (SiC/Pt/CdS) Z-scheme heterojunction nanorod is constructed using a simple chemical reduction-assisted hydrothermal method, in which Pt nanoparticles are anchored at the interface of SiC nanorods and CdS nanoparticles to induce an electron-hole pair transfer along the Z-scheme transport path. Multiple characterization techniques are used to analyze the structure, morphology, and properties of these materials. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results show that the SiC/Pt/CdS materials with good crystal structure are successfully synthesized. Transmission electron microscopy reveals that Pt nanoparticles grow between the interfaces of SiC nanorods and CdS nanoparticles. UV-Vis diffuse reflectance spectroscopy shows that the as-prepared Z-scheme heterojunction samples have a wider light absorption range in comparison with pristine CdS materials. Photoluminescence spectroscopy and the transient photocurrent response further demonstrate that the SiC/Pt/CdS nanorod sample with an optimal molar ratio possesses the highest electron-hole pair separation efficiency. The loading amount of CdS on the surface of SiC/Pt nanorods is effectively adjusted by controlling the molar ratio of SiC and CdS to achieve the optimal performance of the SiC/Pt/CdS nanorod photocatalysts. The optimal H2 evolution capacity is achieved at SiC : CdS = 5 : 1 (molar ratio) and the maximum H2 evolution rate reaches a high value of 122.3 µmol·h−1. In addition, scanning electron microscopy, XRD, and XPS analyses show that the morphology and crystal structure of the SiC/Pt/CdS photocatalyst remain unchanged after three cycles of activity testing, indicating that the SiC/Pt/CdS nanocomposite has a stable structure for H2 evolution under visible light. To prove the Z-scheme transfer mechanism of electron-hole pairs, selective photo-deposition technology is used to simultaneously carry out the photo-reduction deposition of Au nanoparticles and photo-oxidation deposition of Mn3O4 nanoparticles in the photoreaction. The experimental results indicate that during photocatalysis, the electrons in the conduction band of CdS participate mainly in the reduction reaction, and the holes in the valence band of SiC are more likely to undergo the oxidation reaction. The electrons in the conduction band of SiC combine with the holes in the valence band of CdS to form a Z-scheme transport path. Therefore, a possible Z-scheme charge migration path in SiC/Pt/CdS nanorods during photocatalytic H2 production is proposed to explain the enhancement in the activity. This study provides a new strategy for synthesizing a Z-scheme photocatalytic system based on SiC nanorods. Based on the characterization results, it is determined that SiC/Pt/CdS nanocomposites are highly efficient, inexpensive, easy to prepare, and are stable structures for H2 evolution under visible light with outstanding commercial application prospects.

Key words: SiC, Nanorod, SiC/Pt/CdS, Photocatalyst, Z-scheme heterojunction