Unique Pt–C coordination on inner SWCNT surfaces enhances stability of confined Pt nanoparticles

Abstract Encapsulation of Pt nanoparticles within single-walled carbon nanotubes (SWCNTs) is examined as a route to stabilizing sub-2 nm clusters. A sequential process—acid-reflux opening, solution-plasma reduction, and reductive annealing—yields uniform Pt filling. TEM confirms one-dimensional confinement, and XRD/XPS indicate metallic Pt with stabilized Pt 2+ /Pt 0 states. EXAFS identifies Pt–C coordination unique to encapsulated Pt and absent in external Pt/SWCNT. Reactive-force-field molecular dynamics show confinement strengthens Pt–C bonding and suppresses Pt–Pt coalescence during thermal cycling. These results demonstrate SWCNTs as effective confinement hosts for constructing durable, quantum-confined electrocatalyst architectures.