Nanoporous gold made by dealloying AgAuPt (NPG-Pt) has been shown to exhibit several interesting catalytic properties, tied to its exceptionally high surface area; however, structural degradation may occur owing to thermal coarsening. To understand the effect of atmosphere chemistry on thermal coarsening and degradation, and means of limiting it, this study focuses on the high-resolution characterization of NPG-Pt layers coarsened in reductive Ar-H₂ atmosphere, and in oxidative air. Atom probe tomography (APT) analysis is performed on NPG-Pt, coarsened separately in either Ar-H₂ or air, to characterize the atomic-scale chemical changes in the nanoligaments and to develop a mechanistic view of the inherent processes. A tendency of Ag to segregate to the surface during coarsening is found to lead to complete elimination of the nanoligament core-shell structures in both cases. Large Pt segregates form during coarsening in Ar-H₂, but under the surface of the ligaments, having relatively little effect on the coarsening rate. The oxygen-induced segregation of Pt was observed to cause the inhibition of thermal coarsening after minor loss in surface area-to-volume ratio. Findings in this paper help in understanding further the thermal coarsening of heterogeneous nanomaterials made by dealloying, and the pertinent factors that come into play in different chemical environments.

脱银AgAuPt（NPG-Pt）制成的纳米孔金已显示出多种有趣的催化性能，这与其极高的表面积有关。但是，由于热粗化而可能发生结构劣化。为了了解大气化学作用对热粗化和降解的影响以及限制其的手段，本研究着重于在还原性Ar-H ₂气氛和氧化性空气中粗化的NPG-Pt层的高分辨率表征。在NPG-Pt上进行原子探针层析成像（APT）分析，在Ar-H _2中分别进行粗化或空气，以表征纳米配体中原子级的化学变化，并对固有过程进行机理分析。发现在两种情况下，Ag在粗化过程中偏析到表面的趋势都会导致纳米配位核-壳结构的完全消除。在Ar-H _2的粗化过程中，大的Pt偏析形成，但是在韧带的表面下，对粗化速率的影响相对较小。观察到氧诱导的Pt偏析会在表面积/体积比损失较小后抑制热粗化。本文的发现有助于进一步理解通过脱合金制造的异质纳米材料的热粗化，以及在不同化学环境中起作用的相关因素。