An ultrasensitive and highly selective nanomolar electrochemical sensor based on an electrocatalytic peak shift analysis approach for copper trace detection in water

• Published in: Electrochimica acta Vol. 434; p. 141298
• Main Authors: Challier, Lylian, Forget, Amélie, Bazin, Charlène, Tanniou, Simon, Doare, Justine Le, Davy, Romain, Bernard, Hélène, Tripier, Raphael, Laes-Huon, Agathe, Poul, Nicolas Le
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2022; Elsevier
• Subjects: Analytical chemistry; Chemical Sciences; Copper sensor; Electrolyte engineering; Environmental Engineering; Environmental Sciences; Hydrogen evolution reaction; Modified graphite electrode; Peak shift analysis; Hydrogen evolution reaction; Electrolyte engineering; Modified graphite electrode; Peak shift analysis; Copper sensor; peak shift analysis; electrolyte engineering; hydrogen evolution reaction; modified graphite electrode
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2022.141298

•Modified graphite electrodes with cyclam can be used for the passive accumulation of copper ions at open circuit potential.•Nanomolar amounts of copper can be determined by using both stripping and catalytic electrochemical approaches.•Peak shift analysis of the electrocatalytic HER voltammograms allows quantification of copper in the low nanomolar range.•Electrocatalytic proton reduction is highly dependent on electrolyte composition. Copper (Cu) sensing in the nanomolar range is an important challenge for marine water monitoring, especially with eco-friendly materials and reagents. For this purpose, electrochemical Cu(II) sensors appear as fully suitable because of their relatively high sensitivity, selectivity and adaptability for in situ measurements. So far, one of the usual electrochemical methods for Cu(II) sensing is adsorptive anodic stripping voltammetry (AdASV), since it offers a good selectivity, accumulation at open circuit potential and a reliable analytical response for concentrations above 10 nmol.L−1. Surprisingly, no work has ever addressed an electrocatalytic procedure to enhance the electrochemical copper sensing and allowed detection below 10 nM. Thus, we have developed an original two-step strategy based on the surface modification of pencil graphite electrodes (PGE) with p-aminobenzyl-C-functionalized cyclam, a strong chelating ligand for Cu(II), as well as the use of a simple reaction which can be electrocatalyzed by Cu such as HER (Hydrogen Evolution Reaction) to finally determine the accumulated amount of copper catalyst on the PGE. We show here that (i) a well-defined diffusion-limited catalytic peak can be obtained from cyclic voltammetry (CV) experiments with Cu(II)-cyclam-modified PGE, (ii) this HER peak potential is correlated to copper surface concentration, which can be sensed at the same time by adsorptive anodic stripping voltammetry and (iii) peak shift analysis (SA) of the voltammetric curves is a more sensitive method than the commonly used stripping voltammetry to reveal copper accumulation at modified PGE. Indeed, the limit of detection (LOD) reached with this method is one order of magnitude lower compared to AdASV (LOD = 1.1 nM and 16 nM, respectively). These results illustrate the ability of electrocatalysis to be a relevant tool under certain conditions for metal trace detection through SA.