Localized surface plasmon resonances (LSPRs) in metal nanoparticles can drive chemical reactions at their surface, but it is often challenging to disentangle the exact activation mechanism. The decay of LSPRs can lead to photothermal heating, electromagnetic hot spots, and the ejection of nonthermalized charge carriers, but all of these processes typically occur simultaneously and on ultrafast time scales. Here, we develop a plasmon-assisted Au@Ag core@shell nanorod synthesis in which each plasmon-decay mechanism can be independently assessed. Using different illumination wavelengths combined with extinction spectroscopy, transmission electron microscopy, thermal characterization, and finite-difference time-domain simulations, we unequivocally identify the transfer of interband holes to ascorbic acid as the rate-limiting step in the silver shell growth reaction. Our conclusion is corroborated by single-particle studies of gold nanospheres that display isotropic reactivity, consistent with interband hole-driven nanoparticle syntheses. Our strategy for distinguishing among plasmon-activation mechanisms can be extended to a variety of light-driven processes, including photocatalysis, nanoparticle syntheses, and drug delivery.

Three-dimensional (3D) nanomagnetic devices are attracting significant interest due to their potential for computing, sensing, and biological applications. However, their implementation faces great challenges regarding fabrication and characterization of 3D nanostructures. Here, we show a 3D nanomagnetic system created by 3D nanoprinting and physical vapor deposition, which acts as a conduit for domain walls. Domains formed at the substrate level are injected into a 3D nanowire, where they are controllably trapped using vectorial magnetic fields. A dark-field magneto-optical method for parallel, independent measurement of different regions in individual 3D nanostructures is also demonstrated. This work will facilitate the advanced study and exploitation of 3D nanomagnetic systems.

Silver nanowires (AgNWs) combine high electrical conductivity with low light extinction in the visible and are used in a wide range of applications, from transparent electrodes, to temperature and pressure sensors. The most common strategy for the production of AgNWs is the polyol synthesis, which always leads to the formation of silver nanoparticles as byproducts. These nanoparticles degrade the performance of AgNWs' based devices and have to be eliminated by several purification steps. Here, we report a simple and fast synthesis of AgNWs with minimal formation of byproducts, as confirmed by the spectral purity of the final solution. Our synthetic strategy relies on the use of freshly prepared AgCl and on the minimization of gas evolution inside the reaction vessel. The observed synthetic improvements can be of general validity for the polyol synthesis of metallic nanostructures of different shapes and compositions.