(111) Facet-enhancing performance of pure octahedral Cu2O nanocrystal for the electrochemical detection of malachite green

Abstract

ABSTRACT Malachite Green (MG) is a widely used triphenyl alkyl dye, which can cause serious water pollution. Therefore, it is necessary to monitor the MG residue in the environment. In this paper, octahedral cuprous oxide (o-Cu2O) nanoparticle has been synthesised for the modification of glassy carbon electrode (GCE), aiming to determine trace MG by square wave anodic stripping voltammetry (SWASV). Since the exposed (111) crystal facet of o-Cu2O contains abundant unsaturated active ‘copper’ atoms, it can not only enrich MG to the surface of GCE through strong coordination, but also amplify MG response signal due to its excellent electrocatalytic activity. Finally, the electrochemical detection of trace MG can be realized by only using the synthesised o-Cu2O as the electrode modification material. Mechanism studies reveal that the adsorption of MG onto o-Cu2O/GCE surface is controlled by an irreversible ‘two-electron/single-proton’ transfer process. Under optimal conditions, the peak current of MG shows a good linear relationship with its concentration in the range of 0.04 μmol/L − 10 μmol/L and 10 μmol/L − 100 μmol/L, and the limit of detection is 4.57 nmol/L (S/N = 3). This novel electrochemical sensor can be applied for the determination of MG residues in real aquatic products and water resources. In conclusion, this work has successfully developed a simple, economical and environmentally friendly MG analysis method, which can be realized by modifying the electrode with only one single highly active material, providing new possibilities for the efficient detection of similar poisons by electrochemical methods in a more convenient way.