物理化学学报 >> 2023, Vol. 39 >> Issue (10): 2306037.doi: 10.3866/PKU.WHXB202306037

所属专题： 北大纳米化学研究中心30周年专刊

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TiO2负载超低含量AuPd纳米颗粒在水蒸气条件下实现稳定的光催化甲烷偶联生成乙烷

谢君1,2, 蒋雨恒1,2,3, 李思扬1,2, 徐鹏4, 郑强4, 范晓宇1,*(), 彭海琳3,5, 唐智勇1,2,*()   

  1. 1 中国科学院纳米系统与多级次制造重点实验室, 中国科学院卓越纳米科学中心, 国家纳米科学中心, 北京 100190
    2 中国科学院大学, 北京 100049
    3 北京大学前沿交叉学科研究院, 北京 100871
    4 中国科学院纳米标准与检测重点实验室, 北京 100190
    5 北京大学化学与分子工程学院, 北京分子科学国家研究中心, 北京纳米碳科学与工程中心, 纳米化学中心, 北京 100871
  • 收稿日期:2023-06-26 录用日期:2023-07-21 发布日期:2023-08-02
  • 通讯作者: 范晓宇,唐智勇 E-mail:fanxy2022@nanoctr.cn;zytang@nanoctr.cn
  • 作者简介:第一联系人：

    †These authors contributed equally to this work.

  • 基金资助:
    中国科学院战略性先导科技专项(XDB36000000);国家重点基础研究计划(2021YFA1200302);国家自然科学基金(92056204);国家自然科学基金(21890381);国家自然科学基金(21721002)

Stable Photocatalytic Coupling of Methane to Ethane with Water Vapor Using TiO2 Supported Ultralow Loading AuPd Nanoparticles

Jun Xie1,2, Yuheng Jiang1,2,3, Siyang Li1,2, Peng Xu4, Qiang Zheng4, Xiaoyu Fan1,*(), Hailin Peng3,5, Zhiyong Tang1,2,*()   

  1. 1 Chinese Academy of Science (CAS) Key Laboratory of Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
    2 University of Chinese Academy of Sciences, Beijing 100049, China
    3 Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
    4 CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, China
    5 Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
  • Received:2023-06-26 Accepted:2023-07-21 Published:2023-08-02
  • Contact: Xiaoyu Fan, Zhiyong Tang E-mail:fanxy2022@nanoctr.cn;zytang@nanoctr.cn
  • Supported by:
    the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000);National Key Basic Research Program of China(2021YFA1200302);National Natural Science Foundation of China(92056204);National Natural Science Foundation of China(21890381);National Natural Science Foundation of China(21721002)

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摘要：

选择性转化甲烷为C2烃类是一种高效利用天然气并减少对传统化石燃料依赖的方法。与高温高压的热催化途径不同，光催化方法可以在温和条件下实现甲烷活化和选择性转化，是一种非常具有前景的可持续途径。然而，使用廉价光催化剂在流动条件下实现高效C2化合物的生成仍然是一个巨大挑战。本文通过简单的化学还原法合成了一种具有超低负载量的AuPd合金纳米颗粒负载的TiO2光催化剂(Au0.05-Pd0.05/TiO2)，用于光催化甲烷转化。在流动反应条件下，含水蒸气的甲烷可以高效转化为包括乙烷和乙烯在内的C2化合物，C2产率高达10092 μmol∙g−1∙h−1，选择性为77%。更重要的是，在反应持续32 h后，催化活性没有显著降低。Au0.05-Pd0.05/TiO2的光催化甲烷转化的活性和稳定性超过了迄今为止报道的结果。Au0.05-Pd0.05/TiO2良好的催化活性可以归因于金和钯的协同效应，不仅促进了光生载流子的分离而且有利于∙CH3的C-C键耦合进而产生C2化合物。同时，引入水蒸气有助于及时补充在甲烷活化过程中消耗的晶格氧，从而保持催化剂的稳定性。这项工作有望为设计甲烷到C2化合物的可持续光催化转化途径提供一个典范。

关键词: 光催化, 甲烷, 流动反应, 水蒸气, AuPd合金纳米颗粒, C2化合物

Abstract:

The selective conversion of methane to C2 hydrocarbons offers a sustainable approach to utilize natural gas efficiently and reduce reliance on conventional fossil fuels. Unlike the conventional thermal catalytic conversion that requires high temperatures and pressures, the photocatalytic pathway enables methane activation and selective conversion under mild conditions, holding great promise as a sustainable method. However, achieving the efficient generation of C2 compounds under flowing conditions using cost-effective photocatalysts remains great challenge. In this work, we synthesized an ultralow loading AuPd alloy nanoparticle-supported on TiO2 (Au0.05-Pd0.05/TiO2) photocatalyst via simple chemical reduction. Characterization using X-ray diffraction (XRD), aberration corrected high-angle annular dark field scanning transmission electron microscopy (AC-HAADF-STEM) and in situ CO-diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirmed its composition and structure. The performance of the Au0.05-Pd0.05/TiO2 photocatalyst in methane conversion was evaluated under flow-reaction conditions. Remarkably, the photocatalyst efficiently converted methane containing water vapor into C2 compounds, including ethane and ethylene, with a remarkable C2 production rate of up to 10092 μmol∙g−1∙h−1 and a selectivity of 77%. While water vapor was not essential for methane conversion, its presence enhanced the production of ethane and ethylene while suppressing overoxidation to CO2. The photocatalyst demonstrated excellent stability, maintaining its catalytic activity even after continuous reaction for 32 h, surpassing previously reported results. With the assistant of transient photocurrent response test, in situ X-ray photoelectron spectroscopy spectra and in situ DRIFTS, we uncovered that the exceptional catalytic activity of Au0.05-Pd0.05/TiO2 originates from the synergistic effect of Au and Pd, which promotes the separation of photogenerated carriers and facilitates the C-C bond coupling of ·CH3 to produce C2 compounds. Furthermore, XPS characterization revealed that the introduction of water vapor replenished consumed lattice oxygen during the methane activation process, thus contributing to the catalyst's stability. This study not only offers a cost-effective and efficient photocatalyst for methane conversion but also provides insights into the fundamental mechanism of photocatalytic methane conversion. We believe that our work will inspire the exploration of inexpensive catalysts with simple preparation methods, driving advancements in efficient methane to C2 compound conversion and contributing to sustainable photocatalytic pathways for the future.

Key words: Photocatalysis, Methane, Flow-reaction, Water vapor, AuPd alloy nanoparticle, C2 compounds