Single-Atom-Mediated Two-Dimensional Heterointerface Stabilizing 1T-MoS2 for Durable Hydrogen Evolution

The metallic 1T phase of MoS2 provides basal-plane activity and high conductivity that are absent in the semiconducting 2H polymorph, making it attractive for applications in electrocatalysis and energy conversion. However, its intrinsic metastability readily drives relaxation to the 2H ground state, and previous attempts to stabilize 1T-MoS2 have yielded only transient domains or localized perturbations without durable phase retention. Here we show that confining Pt single-atoms (SAs) at the MoS2-graphene heterointerface promotes enhanced stabilization and improved retention of 1T-associated MoS2 signatures, while simultaneously stabilizing the SAs themselves. The interfacial Pt SAs act as atomic-scale anchors, simultaneously redistributing charge and reshaping local coordination to favor the metallic 1T-associated configuration of MoS2. Spectroscopic analyses confirm persistent 1T signatures, and ex situ characterization after operation verifies reliable retention of 1T-MoS2. Density functional theory calculations further corroborate these findings, demonstrating that Pt incorporation reverses the intrinsic phase preference and energetically favors the 1T configuration. Electrochemical measurements further demonstrate nearly unchanged hydrogen evolution activity after 30,000 cycles. Together, these results establish SA-mediated heterointerface engineering as a powerful route to stabilize metastable electronic phases and unlock the full potential of layered materials for energy and electronic technologies.