Tuning and stabilizing the chemical microenvironment of Pt-based single-atom catalysts is a major challenge in promoting an electrocatalytic hydrogen evolution reaction (HER). Herein, we constructed a hierarchical stabilization system of Pt single-atoms via defect substitution using the polyoxometalate (POM) (NH₄)₄[ZnMo₆O₂₄H₆] (ZnMo₆) as a template. The well-defined structure of ZnMo₆ led to precise local Zn sublimation during the formation of Mo₂C, which was converted from the Mo₆ ring in situ. The localized defect provides a well-defined Mo(C)–Pt–N coordination environment to trap Pt single-atoms. The obtained single-atom catalyst (Pt_SA@Mo₂C@NC) exhibited a superior and stable electrochemical HER performance with an unprecedented mass activity of 75.21 A mg_Pt⁻¹ in 0.5 M H₂SO₄. In-depth theoretical calculation analysis revealed that Mo(C)–Pt–N coordination provides a moderated charge state and low d-band center of the Pt site, thus significantly promoting proton adsorption and H₂ desorption. This work demonstrates a promising single-atom stabilization strategy for constructing high-performance HER electrocatalysts through the precise modulation of a three-dimensional chemical environment.

中文翻译：

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由原子取代策略诱导的分级稳定的 Pt 单原子催化剂，用于有效的析氢反应


调节和稳定铂基单原子催化剂的化学微环境是促进电催化析氢反应（HER）的主要挑战。在此，我们通过使用多金属氧酸盐（POM）（NH ₄ ） ₄ [ZnMo ₆ O < b3> H ₆ ] (ZnMo ₆ ) 作为模板。 ZnMo ₆ 明确的结构导致 Mo ₂ C 形成期间精确的局部 Zn 升华，Mo ₂ C 由 Mo ₆ 环原位转化而成。局部缺陷提供了明确的 Mo(C)-Pt-N 配位环境来捕获 Pt 单原子。所得单原子催化剂（Pt _SA @Mo ₂ C@NC）表现出优异且稳定的电化学HER性能，质量活性达到前所未有的75.21 A mg _Pt 于 0.5 M H ₂ SO ₄ 中。深入的理论计算分析表明，Mo(C)-Pt-N配位提供了缓和的电荷态和Pt位点的低d带中心，从而显着促进质子吸附和H ₂ 解吸。这项工作展示了一种有前景的单原子稳定策略，可通过三维化学环境的精确调节来构建高性能 HER 电催化剂。