物理化学学报 >> 2019, Vol. 35 >> Issue (10): 1157-1164.doi: 10.3866/PKU.WHXB201812054

所属专题: 二维材料及器件

论文 上一篇    

构筑先进二维异质结构Ag/WO3x用于提升光电转化效率

任玉美,许群*()   

  • 收稿日期:2018-12-30 录用日期:2019-01-28 发布日期:2019-02-20
  • 通讯作者: 许群 E-mail:qunxu@zzu.edu.cn
  • 基金资助:
    国家自然科学基金(21773216);国家自然科学基金(51173170);国家自然科学基金(21571157);河南省创新人才(114200510019)

Construction of Advanced Two-dimensional Heterostructure Ag/WO3−x for Enhancing Photoelectrochemical Performance

Yumei REN,Qun XU*()   

  • Received:2018-12-30 Accepted:2019-01-28 Published:2019-02-20
  • Contact: Qun XU E-mail:qunxu@zzu.edu.cn
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(21773216);The project was supported by the National Natural Science Foundation of China(51173170);The project was supported by the National Natural Science Foundation of China(21571157);Innovation Talents Award of Henan Province, China(114200510019)

摘要:

等离子体激元诱导的光电化学反应被认为是太阳能转换的有效的替代方案。寻找具有增强的光吸收以及更长载流子寿命的高效光催化剂对于提高太阳能的转换效率至关重要,但其制备却具有挑战性。我们制备了Ag纳米颗粒均匀负载的二维(2D)无定形三氧化钨(a-WO3−x),并对其进行退火处理,所获得的纳米异质结用作光电极材料具有高效的光电转化效率,并且其光氧化降解性能也显著提升。该光电阳极的高光电催化(PEC)性能归因于等离子体金属Ag纳米颗粒的局部表面等离子共振(LSPR)效应能够增强体系的光吸收和热电子转移。此外,局部结晶-非晶界面的构筑可以进一步提高光生电子-空穴对的分离效率并增加体系的导电性。

10.3866/PKU.WHXB201809013.F009  

关键词: 二维材料, 等离子体金属/半导体异质结构, PEC转换

Abstract:

Solar energy, which is clean, affordable and reliable, can help alleviate the current environmental pollution and energy crisis efficiently. In the past few decades, great progress has been made in harvesting and converting solar energy into chemical energy. Among various technologies, plasmon-induced photoelectrochemistry has been proposed as a promising alternative for solar energy conversion. The hot electrons generated from plasmon excitation and transfer from metal nanostructures to semiconductors is a potential new paradigm for solar energy conversion. However, the ultrafast decay of the hot carriers is unfavorable for the improvement of photocatalytic efficiency. Therefore, finding more efficient photocatalysts, with enhanced light absorption and a longer carrier lifetime, is of paramount importance for improving the conversion efficiency of solar energy, but their fabrication is challenging. In this work, a plasmonic metal/semiconductor heterostructure based on Ag nanoparticles embedded in two-dimensional (2D) amorphous sub-stoichiometric tungsten trioxide (a-WO3−x), followed by annealing, was successfully fabricated. Firstly, the peculiar nanostructure of 2D a-WO3−x was successfully constructed from WS2 nanosheets with supercritical CO2 (SC CO2) at 200 ℃. Secondly, the Ag/a-WO3−x heterostructure was synthesized using an in situ reduction method. Finally, the obtained 2D heterostructure of Ag/WO3−x was annealed at 400 ℃ in N2 to further improve its stability and conductivity. X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure, morphology, and composition of the material, respectively. UV-Vis spectra were also measured to evaluate light adsorption. Characterization results show that the amorphous structure can effectively anchor metal nanoparticles, and the metal nanoparticles are uniformly dispersed in the amorphous region and have a small size. The as-prepared nanocomposites showed efficient photoelectrochemical (PEC) water splitting when serving as photoelectrode materials, and efficient PEC activity towards photo-oxidation degradation currents under excitation of Ag localized surface plasmon resonance (LSPR). The photocurrent response of the Ag/WO3−x heterostructure was approximately five times greater than that of a-WO3−x. Moreover, the PEC degradation efficiency of Ag/WO3−x reached 96.7% for MO under Vis light illumination (after reaction for 120 min), while the PEC degradation efficiency of WO3−x was only 63.6%. The high PEC performance of the composite photoanode can be ascribed to the local surface plasmon resonance (LSPR) effect of the Ag nanoparticles, which can enhance the light absorption and hot electron transformation. Moreover, the construction of local crystalline-amorphous interfaces can further promote the separation efficiency of the photogenerated electron-hole pairs, and thus increase conductivity. This work provides a positive strategy for the fabrication of advanced photocatalysts, and a new perspective on understanding of the synergistic effects of structural and electronic regulations.

Key words: Two-dimensional material, Plasmonic metal/semiconductor heterostructure, PEC conversion

MSC2000: 

  • O646