Spectroelectrochemistry is a two-dimensional analytical method combining electrochemical methods, such as cyclic voltammetry (CV), with spectroscopic techniques. It can be used to determine the chemical and physical properties of electroactive species in situ during a potential scan. Potential-dependent measurements of redox-active processes on electrode surfaces can be obtained by observing changes in absorption and emission, or changes in the vibration behaviour of the molecules under investigation. Two informative applications of spectroelectrochemistry are electrochemiluminescence (ECL) and surface-enhanced Raman spectroscopy (SERS) . In ECL, co-reagents react with [Ru(bpy)₃]²⁺ — the molecule that has been most extensively studied in relation to ECL — to produce light emission . Co-reagents can be either oxidising or reducing agents . ECL is used to determine the concentration of co-reagents quantitatively, for example in pharmaceuticals . SERS (surface-enhanced Raman scattering) delete is a spectroscopic technique in which Raman scattering signals from nanomaterials (typically Ag or Au) are amplified. This amplification is caused by localised surface plasmons, which are collective vibrations of surface electrons that lead to strong local amplification of the electromagnetic field near the nanostructure. It is also caused by chemical interactions between molecules and nanometal surfaces . Nanoparticles (and thus SERS) can simply be generated electrochemically by applying first positive and then negative potentials to an Au or Ag electrode in an electrolyte solution (between 0 and 1.3 V and back for Au and between -0.3 and 0.5 V and back for Ag). After the anodic potential scan, nanostructures form during subsequent delete cathodic potential control when the metal is reduced from its oxidised state on the surface. This leads to a significant enhancement of the Raman effect: EC-SERS (electrochemically induced SERS) . ECL with reductive and oxidative co-reagents and cathodic EC-SERS are both classic spectroscopic methods. This article focuses on two novel electrochemical methods that have recently emerged: co-reagent-free ECL and EC-SOERS (electrochemically induced surface-enhanced oxidative Raman spectroscopy). Furthermore, we demonstrate that low-cost copper can be used to generate both co-reagent-free ECL and SERS.

ECL without co-reagent, anodic EC-SERS: EC-SOERS, ECL and EC-SERS with copper