催化学报

催化学报

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同时实现Pt/C催化剂的超高载量和超细粒径

王效阳a, 傅梓淇a, 罗子怡a, 刘威迪b, 丁佳a, 曾建荣c,d,*, 陈亚楠a,*, 胡文彬a,*   

  1. a天津大学材料科学与工程学院, 天津 300350, 中国;
    b昆士兰大学生物工程与纳米技术研究所, 布里斯班, 澳大利亚;
    c中国科学院上海高等研究院, 上海光源科学中心, 上海 201204, 中国;
    d中国科学院上海应用物理研究所, 上海 201800, 中国
  • 收稿日期:2025-01-13 接受日期:2025-02-06
  • 通讯作者: * 电子信箱: yananchen@tju.edu.cn (陈亚楠); wbhu@tju.edu.cn (胡文彬); zengjr@sari.ac.cn (曾建荣).
  • 基金资助:
    国家自然科学基金(52171219, 92372107, XD24022).

Simultaneously achieving ultrahigh loading and ultrasmall particle size of Pt/C catalysts

Xiaoyang Wanga, Ziqi Fua, Ziyi Luoa, Weidi Liub, Jia Dinga, Jianrong Zengc,d,*, Yanan Chena,*, Wenbin Hua,*   

  1. aSchool of Materials Science and Engineering, Tianjin University, Tianjin 300350, China;
    bAustralian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, Brisbane 4072, Australia;
    cShanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China;
    dShanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
  • Received:2025-01-13 Accepted:2025-02-06
  • Contact: *E-mail: yananchen@tju.edu.cn (Y. N. Chen), wbhu@tju.edu.cn (W. B. Hu), zengjr@sari.ac.cn (J. R. Zeng).
  • Supported by:
    The National Natural Science Foundation of China (52171219, 92372107, XD24022).

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摘要： 迄今为止,Pt/C依然是质子交换膜电解水(PEMWE)中最有效的商业化析氢反应(HER)催化剂.然而,大多数报道的碳负载型铂基催化剂的铂负载量普遍低于20%.在实际应用中,低载量会导致膜电极中催化剂层增厚,显著增大传质阻力并造成PEMWE的性能严重衰减.然而,载量增大会加剧Pt纳米颗粒的生长和团聚,现有的高载量商业Pt/C催化剂普遍存在粒径粗化和分散性差的问题,严重制约其催化效率与使用寿命.遗憾的是,关于如何突破高金属负载量与纳米颗粒分散之间"跷跷板效应"的研究文章寥寥无几.鉴于高载量Pt/C在催化领域的广泛应用,开发一种在40 wt%以上超高载量下同时实现超细粒径的有效策略是非常必要的.
近年来,高温热冲击(HTS)技术已成功应用于多种碳载体上均匀分布金属纳米颗粒的超快原位合成.该技术可以精细调控反应过程中的烧结时间和冷却速度,最小化纳米颗粒的迁移聚集.本文提出了一种简单高效、低成本的HTS热解策略,以Vulcan XC-72R炭黑为载体,成功制备了一系列具有超高载量(39.01wt%,48.6wt%,58.05wt%,66.48wt%)和超细粒径(~2.5nm)的Pt/C催化剂.该方法以乙酰丙酮铂为前驱体,只需对原始炭黑做简单的预功能化处理,无需任何表面活性剂或封端剂等添加剂,展现出了强大的规模化生产潜力和普适性.受益于HTS瞬间的能量输入,炭黑载体上预吸附的乙酰丙酮铂前驱体发生快速分解、还原,实现细小均匀铂纳米颗粒的原位合成.X射线光电子能谱和拉曼光谱等结果表明,改性处理不仅显著增加了XC-72R炭黑的比表面积和孔隙体积,而且在其表面引入了大量的结构缺陷和含氧官能团.Zeta电位测试显示,改性炭黑载体与乙酰丙酮铂前驱体之间存在着更强的静电相互作用,极大的提高了二者之间的亲和力,使Pt的负载效率高达95%以上,有利于降低Pt/C催化剂的制备成本.另一方面,丰富的结构缺陷和含氧官能团还可以提供大量成核位点,大幅提高铂的成核速率,抑制铂纳米颗粒生长并作为锚定位点阻止其迁移聚集.这些作用之间的有机协同实现了铂纳米颗粒的粒径控制和高度分散,最终得到均匀细小的超高载量Pt/C催化剂.此外,含氧官能团优化了铂纳米颗粒的表面电子结构、增强了纳米颗粒与炭黑之间的金属-载体相互作用并改善了电解质与催化剂表面的接触.因此,三电极体系中的电化学测试结果表明,相比于最先进的商业JM-Pt/C,所制备的超高载量Pt/C催化剂在酸性介质中表现出显著提高的HER活性和稳定性.以所得58.05wt% Pt/C催化剂为例,与商业IrO2催化剂分别作为阴阳极组装而成的PEMWE电解槽达到1A cm-2电流密度的电池电压为1.77V,稳定性测试电压衰减速率为50μV h-1,两项指标均远低于商业JM-60wt% Pt/C(1.82V和200μV h-1).
综上所述,本工作通过HTS热解策略成功突破传统Pt/C催化剂制备中高载量与纳米颗粒分散的矛盾,为设计兼具超高金属负载与精细粒径调控的催化剂提供了新范式,为其他金属/碳基催化体系(如Ir/C,Ru/C)的构建提供了重要参考.

关键词: Pt/C催化剂, 超高载量, 超细粒径, 高温热冲击, 质子交换膜电解水

Abstract: High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer, which enhance mass transport and maintain the balance of water and heat. Unfortunately, as the loading increases, the agglomeration and growth of Pt nanoparticles (NPs) occur, causing unsatisfactory performance. Here, we present an efficient method for preparing of highly dispersed and small-sized Pt/C catalysts with Pt loadings varying from 39.01 wt% to 66.48 wt% through the high-temperature shock technique. The high density and ultrafine (~2.5 nm) Pt NPs are successfully anchored onto Vulcan XC-72R carbon black without the use of additional capping agents or surfactants. The modified carbon supports enhance the affinity for Pt precursors, contributing to loading efficiencies of 95% or more, while also providing abundant sites for the nucleation and fixation of Pt NPs, thus preventing agglomeration. In the context of the hydrogen evolution reaction in acidic media, the as-synthesized high-loading Pt/C catalysts show remarkable activity and stability, outperforming the state-of-the-art commercial Pt/C. This is mainly because the combined effects of ultrasmall and uniform Pt NPs, optimized electronic structure of Pt site, superhydrophilicity and effective anchoring of Pt NPs. The polymer electrolyte membrane electrolyzer integrated with Pt60/OX72R and commercial IrO2 reaches 1 A cm-2 at 1.77 V and operates stably for 120 hours with a negligible voltage decay. This new strategy is fast, scalable and cost-effective for large-scale production of metal-supported catalysts, especially for the high-loading ones.

Key words: Pt/C catalyst, Ultrahigh loading, Ultrasmall size, High-temperature shock, Proton exchange membrane water electrolysis