AuPtAg In-Plane Core-Shell Nanoplates via Strain-Mediated Growth for NIR Plasmonic Catalysis and Photothermal Conversion.

The rational design of nanostructures that efficiently harness near-infrared (NIR) light is paramount for advancing plasmonic catalysis and photothermal applications. While anisotropic noble metal nanocrystals can be tuned to absorb in the NIR, integrating them with catalytically active metals to form well-defined heterostructures with optimal interfacial charge transfer remains a significant synthetic challenge. Herein, we demonstrate a strain-mediated spatial growth strategy to fabricate NIR-responsive AuPtAg in-plane core-shell nanoplates. By exploiting lattice mismatch, we spatially confine the secondary growth of gold, resulting in 2D heterostructures where a continuous PtAg shell encircles a plasmonic Au core. This unique architecture functions as a dual-mode platform, exhibiting an optimal photothermal conversion efficiency of 46% (under 1064 nm laser, 1 W cm-2) and enhanced catalytic activity for the 4-nitrophenol reduction under low-energy 810 nm LED irradiation (10 W). Theoretical simulations confirm that the design enables efficient plasmon excitation and subsequent charge transfer to the catalytic shell. This work provides a novel paradigm for fabricating precise 2D multimetallic heterostructures and offers a model system for probing interfacial processes in NIR-driven plasmonic catalysis and photothermal conversion.