Controlled Synthesis of Janus Au-AgCl Cores Encapsulated by Amorphous Ru/RuO x Shells and Their Plasmonic Catalytic Performance

Complex yolk–shell nanostructures offer significant advantages for catalytic applications due to their high surface area, enhanced mass transport, and structural stability. This work presents a rationally designed yolk–shell architecture comprising a Janus Au-AgCl core enclosed within an amorphous Ru/RuOx shell, synthesized via a controlled galvanic replacement process. The unique Janus core introduces spatially asymmetric electronic properties that facilitate directional charge transfer, while the amorphous Ru/RuOx shell provides a high density of accessible active sites. When illuminated by a 10 W, 590 nm LED, this nanostructure drives the plasmonic catalytic reduction of 4-nitrophenol (4-NP) with improved kinetics and conversion efficiency. FEM simulation suggested that the Au-AgCl@RuO2 composite nanoparticle achieves the highest hot-electron generation rate across the visible-to-near-infrared range, owing to the porous RuO2 shell that enhances plasmonic coupling, redshifts the resonance peak, and facilitates efficient hot-electron transport through its excellent electrical conductivity. This study highlights the potential of multicomponent, morphology-engineered yolk–shell architectures as a versatile platform for advanced plasmonic catalysts.