A spectroelectrochemistry device capable of studying different regions of an electrode surface in a strictly simultaneous way is presented in this work. It is based on two reflection probes placed in a near-normal arrangement with respect to a working electrode surface, part of which has been deliberately modified. As expected, the electrochemical signal contains information related to the whole system, it being impossible to distinguish which behaviour corresponds to the unmodified and which to the modified part of the electrode. Spectroelectrochemistry provides an excellent solution because the reflection probes fully explain the electrochemical response, allowing deconvolution of the electrochemical behaviour from an optical point of view under exactly the same experimental conditions. To demonstrate the usefulness of this platform, a highly oriented pyrolytic graphite electrode is partially modified with commercially available carbon nanotubes or graphene, and the oxidation of dopamine at the different parts of the electrode is studied simultaneously. A remarkable decrease in the onset oxidation potential is observed at the modified surfaces compared to the bare electrode. This work highlights the advantages of spectroelectrochemistry for the characterization of materials and the comparison of electrode surfaces, laying the groundwork for novel experiments in which simultaneous measurement is a key factor.
