Zhang Bentian, Fu Gengtao, Li Yutao, Liang Lecheng, Grundish Nicholas S, Tang Yawen, Goodenough John B, Cui Zhiming
The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510641, China.
Materials Science and Engineering Program & Texas Materials Institute, The University of Texas at Austin, Austin, Texas, USA.
Angew Chem Int Ed Engl. 2020 May 11;59(20):7857-7863. doi: 10.1002/anie.201916260. Epub 2020 Mar 18.
Controllable synthesis of atomically ordered intermetallic nanoparticles (NPs) is crucial to obtain superior electrocatalytic performance for fuel cell reactions, but still remains arduous. Herein, we demonstrate a novel and general hydrogel-freeze drying strategy for the synthesis of reduced graphene oxide (rGO) supported Pt M (M=Mn, Cr, Fe, Co, etc.) intermetallic NPs (Pt M/rGO-HF) with ultrasmall particle size (about 3 nm) and dramatic monodispersity. The formation of hydrogel prevents the aggregation of graphene oxide and significantly promotes their excellent dispersion, while a freeze-drying can retain the hydrogel derived three-dimensionally (3D) porous structure and immobilize the metal precursors with defined atomic ratio on GO support during solvent sublimation, which is not afforded by traditional oven drying. The subsequent annealing process produces rGO supported ultrasmall ordered Pt M intermetallic NPs (≈3 nm) due to confinement effect of 3D porous structure. Such Pt M intermetallic NPs exhibit the smallest particle size among the reported ordered Pt-based intermetallic catalysts. A detailed study of the synthesis of ordered intermetallic Pt Mn/rGO catalyst is provided as an example of a generally applicable method. This study provides an economical and scalable route for the controlled synthesis of Pt-based intermetallic catalysts, which can pave a way for the commercialization of fuel cell technologies.
可控合成原子有序的金属间化合物纳米颗粒（NPs）对于获得优异的燃料电池反应电催化性能至关重要，但仍然具有挑战性。在此，我们展示了一种新颖且通用的无凝胶冷冻干燥策略，用于合成具有超小粒径（约3 nm）和显著单分散性的还原氧化石墨烯（rGO）负载的PtM（M = Mn、Cr、Fe、Co等）金属间化合物纳米颗粒（PtM/rGO-HF）。水凝胶的形成可防止氧化石墨烯聚集，并显著促进其优异的分散性，而冷冻干燥可保留水凝胶衍生的三维（3D）多孔结构，并在溶剂升华过程中将具有确定原子比的金属前驱体固定在氧化石墨烯载体上，这是传统烘箱干燥所无法实现的。随后的退火过程由于3D多孔结构的限制效应，生成了rGO负载的超小有序PtM金属间化合物纳米颗粒（≈3 nm）。此类PtM金属间化合物纳米颗粒在已报道的有序Pt基金属间化合物催化剂中粒径最小。以有序金属间化合物PtMn/rGO催化剂的合成为例，对其合成过程进行了详细研究，这是一种普遍适用的方法。本研究为可控合成Pt基金属间化合物催化剂提供了一种经济且可扩展的途径，可为燃料电池技术的商业化铺平道路。
