催化学报 ›› 2022, Vol. 43 ›› Issue (2): 451-460.DOI: 10.1016/S1872-2067(21)63879-2

• 论文 • 上一篇    下一篇

铜铂双单原子负载晶化氮化碳及其增强光催化CO2还原性能

程蕾a,b, 张鹏c, 文岐业a, 范佳杰c, 向全军a,b,*()   

  1. a电子科技大学电子科学与工程学院, 电子薄膜与集成器件国家重点实验室, 四川成都 610054
    b电子科技大学长三角研究院(湖州), 浙江湖州 313001
    c郑州大学材料科学与工程学院, 河南郑州 450001
  • 收稿日期:2021-04-28 接受日期:2021-05-21 出版日期:2022-02-18 发布日期:2021-07-07
  • 通讯作者: 向全军
  • 基金资助:
    国家自然科学基金(51672099);国家自然科学基金(52073263);四川省科技计划资助(2021JDTD0026);中央高校基金(2017-QR-25)

Copper and platinum dual-single-atoms supported on crystalline graphitic carbon nitride for enhanced photocatalytic CO2 reduction

Lei Chenga,b, Peng Zhangc, Qiye Wena, Jiajie Fanc, Quanjun Xianga,b,*()   

  1. aState Key Laboratory of Electronic Thin Film and Integrated Devices, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan, China
    bYangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, Zhejiang, China
    cSchool of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, Henan, China
  • Received:2021-04-28 Accepted:2021-05-21 Online:2022-02-18 Published:2021-07-07
  • Contact: Quanjun Xiang
  • Supported by:
    This work was supported by the National Natural Science Foundation of China(51672099);This work was supported by the National Natural Science Foundation of China(52073263);Sichuan Science and Technology Program(2021JDTD0026);Fundamental Research Funds for the Central Universities(2017-QR-25)

摘要:

铂单原子作为一种新型催化剂, 具有活性组分高度分散、配位未饱和以及原子利用率高等特点, 在光催化还原CO2方面表现出巨大潜力. 但是由于成本高昂和负载量高等因素, 极大地限制了其在实际生产中的广泛应用. 合成具有低负载量贵金属铂, 同时提高铂基单原子催化剂的催化活性仍然是一项巨大挑战. 晶化石墨相氮化碳的二维结构, 特别是其稳定晶化结构所形成的限域环境及其可扩展的π共轭单元, 可以有效锚定金属单原子, 因而可作为金属单原子的良好载体. 已有的金属单原子载体氮化碳多为弱晶或非晶结构, 基于晶化氮化碳的高结晶度和高结构稳定性, 合理构建金属单原子沉积的结晶石墨相氮化碳体系仍十分困难. 关于晶化氮化碳负载金属单原子催化剂应用于光催化还原CO2的研究至今鲜有报道.
本文开发了一种具有低负载量的铂基双单原子锚定晶化氮化碳的制备方法, 通过设计氮化碳缺陷位点, 在晶化石墨相氮化碳载体表面构筑氮缺陷位点, 利用载体的丰富氮缺陷作为陷阱, 有效捕获双单原子金属前驱体, 成功制备了具有低负载量(铂为0.32 wt%)的双金属铜铂单原子催化剂, 并用于光催化CO2还原反应中. 结果表明, 相比于单原子铂催化剂和单原子铜催化剂, 该种双单原子铜铂体系在光催化还原CO2-CO中表现了更好催化活性. 在光照3.5 h后, 铜铂双单原子体系的CO产量达到41.1 μmol g -1. 除此之外, 铜铂双单原子体系在光催化过程中有利于促进CH4生成, 在没有任何牺牲剂或共催化剂作用下其CH4的产量为9.8 μmol g -1, 其产率分别是相同光照条件下单原子铂催化剂(3.2 μmol g -1)和单原子铜催化剂(2.0 μmol g -1)的三倍和五倍.
高分辨透射电镜结果表明, 制备的氮化碳呈现了高度晶化的结构. 球差扫描透射电子显微镜结果表明, 铂和铜物种分别以高度分散的单原子形式存在, 且在双金属铜铂单原子体系并未发现铜颗粒和铂颗粒. 电化学分析结果表明, 通过双配位活性位点的桥梁作用提高光生电子的转移效率, 使得铜铂双单原子体系具有更高的电流密度和更好的载流子传输能力. 原位X射线光电子能谱结果表明, 金属铂和铜单原子成功负载在晶化石墨相氮化碳上, 且在光照过程中单原子铂和铜的结合能的电子密度有些许改变, 证明了该双金属单原子体系在光催化过程中协同动态光电子的迁移转移; 原位红外傅里叶变换光谱实验结果表明, 这种稳定的铜铂双单原子体系有利于促进催化还原反应中中间体产物的加氢过程, 对终产物的解离和释放有明显的促进作用, 从而提高光催化还原CO2反应的活性和选择性.

关键词: 铜铂双单原子, 晶化氮化碳, 光催化还原CO2, 低负载量, 协同光催化

Abstract:

Single-atom Pt catalysts are designed to promote efficient atom utilization, whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing. Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability. In this study, we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO2 reduction. N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers. The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride (PtCu-crCN) exhibited high selectivity and activity for CO2 conversion without the addition of any cocatalyst or sacrificial agent. In particular, we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH4 generation. The mechanism of CO2 photoreduction for PtCu-crCN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images, in situ irradiated X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.

Key words: Dimetal Pt-Cu atom, Crystalline carbon nitride, Photocatalytic CO2 reduction, Low loading, Synergistic photocatalysis