物理化学学报 >> 2018, Vol. 34 >> Issue (6): 708-718.doi: 10.3866/PKU.WHXB201710162

论文 上一篇    下一篇

聚胺界面修饰改善碳量子点可见光光敏化性能

李少海,翁波,卢康强,徐艺军*()   

  • 收稿日期:2017-07-27 发布日期:2018-03-20
  • 通讯作者: 徐艺军 E-mail:yjxu@fzu.edu.cn
  • 基金资助:
    国家自然科学基金(U1463204);国家自然科学基金(21173045);闽江学者特聘教授科研启动基金,福建省杰出青年自然科学基金滚动资助项目(2017J07002);能源与环境光催化国家重点实验室自主课题(2014A05);福建省首批特支人才“双百计划”青年拔尖创新人才,厦门大学固体表面物理化学国家重点实验室开放课题(201519);教育部留学回国人员科研启动基金项目

Improving the Efficiency of Carbon Quantum Dots as a Visible Light Photosensitizer by Polyamine Interfacial Modification

Shaohai LI,Bo WENG,Kangqiang LU,Yijun XU*()   

  • Received:2017-07-27 Published:2018-03-20
  • Contact: Yijun XU E-mail:yjxu@fzu.edu.cn
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(U1463204);The project was supported by the National Natural Science Foundation of China(21173045);the Award Program for Minjiang Scholar Professorship, China, the Natural Science Foundation (NSF) of Fujian Province for Distinguished Young Investigator Rolling Grant, China(2017J07002);the Independent Research Project of State Key Laboratory of Photocatalysis on Energy and Environment, China(2014A05);the 1st Program of Fujian Province for Top Creative Young Talents, the Open Research Project of State Key Laboratory of Physical Chemistry of Solid Surfaces of Xiamen University, China(201519);the Program for Returned High-Level Overseas Chinese Scholars of Fujian Province, China

摘要:

在新兴能源的存储与转化技术中,碳量子点作为新一代光吸收组分得到越来越广泛的关注。然而目前关于对碳量子点复合体系界面的改性,进而有效提高碳量子点光敏化性能的研究还较少。在本研究工作中,我们通过一种简单的静电自组装的方法构建催化体系,碳量子点能够很好地分散在枝状聚乙烯亚胺修饰的二氧化钛表面,其中碳量子点在复合体系中质量分数约为5%(w, mass fraction)时,展现出最优的可见光还原对硝基苯胺的活性。整体活性相比没有经过修饰的二氧化钛/碳量子点复合体系以及作为参比的枝状聚乙烯亚胺修饰的二氧化硅/碳量子点复合体系均有较明显的提高。结构与光谱研究表明,碳量子点与聚乙烯亚胺修饰的二氧化钛形成了较好的界面接触;进一步通过对比二氧化硅复合体系与二氧化钛复合体系表明,枝状聚乙烯亚胺可作为电子传输通道,能够有效地促进光生电子的分离与传递。因此,得益于良好的界面接触与有效地光生载流子的传递,相比未修饰的复合体系,枝状聚乙烯亚胺修饰的二氧化钛/碳量子点展现出更好地光催化反应活性。此研究工作中界面优化的手段,可将二氧化钛/碳量子点复合体系进一步拓展到其他宽带隙半导体光催化体系并设计构建有效的碳量子点基的半导体光吸收体系。

关键词: 碳量子点, 敏化, 枝状聚乙烯亚胺, 光催化, 半导体

Abstract:

Carbon quantum dots (CQDs) are emerging as the new-generation light absorber for solar energy conversion. However, the low photosensitization efficiency of CQDs is one of the current bottlenecks impeding their large-scale practical applications in photocatalysis. Therefore, developing a facile approach for the engineering and functionalization of CQDs-based composites to improve the photosensitization efficiency of CQDs is highly desirable. On account of the abundant functional groups, especially oxygen-containing functional groups such as carbonyl, carboxyl, and hydroxyl present on their surface, CQDs can be readily combined with various organic molecules or polymers as a surface passivation component to reduce the nonradioactive surface recombination of photo-generated charge carriers, thus enabling the CQDs to exhibit strong photoluminescence in the visible and near-infrared spectral regions. Consequently, polymer passivation has been demonstrated as an ideal strategy to make it accessible for improving the sensitization efficiency of CQDs in photocatalytic applications. Branched polyethylenimine (BPEI) is one of polymers that contains a high density of amine groups and exhibits high electron mobility, which can be used as an electron injection material at the interface of nanomaterials. Besides, the BPEI polymer with amino groups exhibiting positive charge has been utilized for designing heterogeneous catalysts by an electrostatic self-assembly strategy. Therefore, BPEI is expected to modify the surface of inorganic oxides semiconductor to enhance the photosensitization efficiency of CQDs under visible light. However, to date, the study in this regard has been still unavailable. In this work, we developed a facile approach to engineer well-distributed CQDs via electrostatic interaction on BPEI passivated TiO2 composites (BTC) as photocatalysts. The BTC composites with an optimal loading of 5% (w, mass fraction) CQDs outperformed the TiO2/CQDs (TC) composite and referential BPEI/SiO2/CQDs (BSC) composites for the photoreduction of 4-nitroaniline under visible light irradiation. The structure of the fabricated BTC composites was systematically investigated by the combined use of structural and spectral characterizations, demonstrating that the photosensitizer CQDs contacted well with the BPEI modified TiO2 nanoparticles. The comparison characterizations revealed that BPEI facilitated the dissociation and transfer of excitons as an electron transfer channel. The as-prepared BTC composites benefited from the favorable interfacial contact and effective transfer of photo-generated charge carriers, and thus manifested superior photocatalytic activity to the TC composite. It is expected that this strategy would be extended to other wide band gap semiconductor photocatalyst systems and open up new possibilities in designing efficient CQDs-based semiconductor artificial light harvesting systems by interfacial optimization.

Key words: Carbon quantum dots, Sensitization, Branched polyethylenimine, Photocatalysis, Semiconductor

MSC2000: 

  • O649