Search for: All records

Plasmonic metal nanostructures are essential for plasmon‐mediated chemical reactions (PMCRs) and surface‐enhanced Raman spectroscopy (SERS). The nanostructures are commonly made from the coinage metals gold and silver. Copper (Cu) is less used mainly due to the difficulties in fabricating stable nanostructures. However, Cu is an attractive option with its strong plasmonic properties, high catalytic activities, and relatively cheap price. Herein, we fabricated tunable, reliable, and efficient Cu nanoelectrodes (CuNEs). Using time‐resolved electrochemical SERS, we have comprehensively studied the reversible chemical transformations between aromatic amine and nitro groups modified on the CuNE surface. Their PMCRs are well‐controlled by changing the surface roughness, the oxidation states of Cu, and the applied electrode potential. We thus demonstrate that the Cu nanostructures enable better investigations in the interplays between PMCR, electrochemistry, and Cu catalysis.

 

A plasmon-driven deprotonation reaction of the aromatic methyl group can occur in aqueous solution under the illumination of red light. The reaction produces a benzyl radical and anion, and dimers through a self-reaction.

 

Single-entity electrochemistry is of fundamental importance and shows promise for ultrasensitive biosensing applications. Recently, we have demonstrated that various charged nanoparticles can be detected individually based on the non-redox open-circuit potential (OCP) changes induced by their collision events on a floating carbon nanoelectrode (CNE). Unlike the widely used amperometry approach, the potentiometric method provides the label-free detection of individual nanoscale entities without redox mediators in the solution. However, the CNE lacks specificity for molecular recognition during the collision events because of the limited methods of surface functionalization for carbon surfaces. Herein, we used surface-functionalized gold nanoelectrode (GNE) to overcome this limitation of CNE. The GNE modified with Raman reporter molecule also enabled surface-enhanced Raman spectroscopy (SERS) measurements. By using simultaneous time-resolved OCP and SERS measurements, both the OCP and SERS signals induced by the “hit-n-run” type of gold nanoparticle (GNP) collision events can be better understood. Also, by introducing a zwitterionic molecule, we formed near “stealth” surface and demonstrated that the non-specific adsorptions of GNPs to the surface of GNE have been suppressed, allowing continuous detection of hit-n-run events for over 30 min.