Origin of Stability and Activity Enhancements in Pt‐based Oxygen Reduction Reaction Catalysts via Defect‐Mediated Dopant Adsorption
Origin of Stability and Activity Enhancements in Pt‐based Oxygen Reduction Reaction Catalysts via Defect‐Mediated Dopant Adsorption
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通过缺陷介导的掺杂剂吸附提高 Pt 基氧还原反应催化剂的稳定性和活性的起源
DOI：
10.1002/ange.202312747
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发表时间：
2023
影响因子：
--
通讯作者：
Greeley, Jeffrey P.
中科院分区：
文献类型：
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作者：
Sawant, Kaustubh J.;Zeng, Zhenhua;Greeley, Jeffrey P.
铂合金是酸性条件下氧还原反应(ORR)的高效电催化剂。然而，这些合金容易通过浸出和降解而损失金属，导致催化剂的稳定性和活性降低。最近，亲氧元素的掺杂可以显著缓解这些问题，其中一个突出的例子是Mo掺杂的铂合金。在这里，为了实现对这些合金的特殊活性和稳定性的原子尺度的理解，我们给出了掺杂的结构和对电催化剂性能的影响的详细的密度泛函理论描述。从Mo/Pt体系出发，我们证明了Mo可以以低维氢氧化物的形式稳定在铂缺陷上。得到的结构通过不同的物理过程提高了稳定性和活性，其中Mo部分既直接抑制了缺陷处的铂溶解，又通过在周围的铂平台上产生应变场而间接地增强了ORR的活性。然后我们将这些分析推广到其他金属掺杂元素，并证明了类似的低维氢氧化物结构通过结构的酸稳定性、对ORR的本征活性以及在铂上诱导ORR促进应变场的能力之间的复杂相互作用来控制电催化性能。
Platinum alloys are highly efficient electrocatalysts for the oxygen reduction reaction (ORR) in acidic conditions. However, these alloys are susceptible to metal loss through leaching and degradation, leading to reduced catalyst stability and activity. Recently, it has been shown that doping with oxophilic elements can significantly alleviate these problems, with a prominent example being Mo‐doped Pt alloys. Here, to achieve atomic scale understanding of the exceptional activity and stability of these alloys, we present a detailed density functional theory description of the dopants’ structures and impact on electrocatalyst properties. Beginning with the Mo/Pt system, we demonstrate that Mo can be stabilized in the form of low‐dimensional oxyhydroxide moieties on Pt defects. The resulting structures enhance stability and activity via distinct physical processes, with the Mo moieties both directly inhibiting Pt dissolution at defects and indirectly enhancing ORR activity by generation of strain fields on surrounding Pt terraces. We then generalize these analyses to other metal dopant elements, and we demonstrate that similar low‐dimensional oxyhydroxide structures control the electrocatalytic properties through an intricate interplay of the structures’ acid stability, intrinsic activity for the ORR, and ability to induce ORR‐promoting strain fields on Pt.