Application of atomic layer deposition in fabricating high-efficiency electrocatalysts

原子层沉积方法在设计制备高效电催化剂中的应用（英文）

Electrocatalysis is a promising approach to clean energy conversion due to its high efficiency and low environmental pollution. Noble metal materials have been studied to show high activity toward electrocatalyltic reactions, although such applications remain restricted by the high cost and poor durability of the noble metals. By precisely adjusting the catalyst composition, size, and structure, electrocatalysts with excellent performance can be obtained. Atomic layer deposition(ALD) is a technique used to produce ultrathin films and ultrafine nanoparticles at the atomic level. It possesses unique advantages for the controllable design and synthesis of electrocatalysts. Furthermore, the homogenous composition and structure of the electrocatalysts prepared by ALD favor the exploration of structure-reactivity relationships and catalytic mechanisms. In this review, the mechanism, characteristics, and advantages of ALD in fabricating nanostructures are introduced first. Subsequently, the problems associated with existing electrocatalysts and a series of recently developed ALD strategies to enhance the activity and durability of electrocatalysts are presented. For example, the deposition of ultrafine Pt nanoparticles to increase the utilization and activity of Pt, fabrication of core–shell, overcoat, nanotrap, and other novel structures to protect the noble-metal nanoparticles and enhance the catalyst stability. In addition, ALD developments in synthesizing non-noble metallic electrocatalysts are summarized and discussed. Finally, based on the current studies, an outlook for the ALD application in the design and synthesis of electrocatalysts is presented.

人类对不可再生化石能源的依赖导致了全球范围内的能源危机和环境污染.电化学能源转换技术由于具有清洁、高效、原料来源广泛及可再生等优点而受到广泛关注.电催化剂能加快反应动力学,提高目标产物选择性,在电化学能源转换技术中起着至关重要的作用.目前, Pt是多数重要的电化学反应(如电解水、氧还原以及一些小分子醇类和酸类的氧化反应)中使用最多和最有效的催化剂之一.然而Pt催化剂面临着价格昂贵、易中毒、易流失等问题,使其在大规模工业化应用中受到限制.为了提高Pt催化剂的利用率和稳定性,研究人员进行了大量工作.例如,制备尺寸小的Pt纳米颗粒,增加单位质量Pt表面积和Pt利用率;在Pt催化剂中加入Ru或Pd等其它金属,促进醇类和酸类氧化反应中间产物的氧化,减缓Pt中毒;选用抗腐蚀性能好的载体,增加Pt与载体间相互作用,从而抑制Pt颗粒在高电位、高湿度、高酸碱度电化学工作环境中的脱落和聚集.尽管如此,利用传统的方法仍然很难精确调控电催化剂的组成、尺寸和纳米结构,无法最大程度提高贵金属Pt的利用效率.原子层沉积(ALD)技术可在原子尺度控制物质生长,既能在多孔、复杂基体上沉积尺度均一的纳米薄膜或颗粒,也能精确调控、构筑各类纳米结构.本文总结了近年来利用ALD技术制备高性能电催化剂的代表性研究进展.文章首先介绍了ALD反应机理、载体表面官能团对ALD生长的促进作用以及ALD制备方法对催化剂金属-载体相互作用的影响等基本原理和知识.总结了利用ALD技术制备高活性Pt催化剂的各种方法,包括制备超细纳米颗粒,纳米线、纳米薄膜、纳米管,纳米3D结构等不同形貌Pt催化剂等.介绍并探讨了利用ALD构筑纳米陷阱、包覆超薄多孔碳膜/氧化物膜、选择性修饰载体等提高Pt催化剂稳定性的策略.文章还介绍了如何通过调节ALD反应温度、前驱体种类,以及利用选择性沉积等方法,精确调控双贵金属电催化剂中金属的比例、尺寸、结构等以提高催化剂性能,并重点阐述了双金属核壳催化剂的制备方法.此外,文章还概述了ALD方法制备非贵金属催化剂的研究进展.最后,文章总结了ALD技术在设计、制备电催化剂领域的优势和不足,展望了ALD在该领域的发展和应用前景,为设计、制备高性能电催化剂提供了参考.