Rapid electrochemical conversion of smooth Cu surfaces to urchin-like Cu nanowire arrays via flower-like Cu2Se nanosheets as an advanced nonenzymatic glucose sensor

Abstract

A novel surface conversion of smooth copper electrodes into flower-like Cu2Se nanosheets is realized in 5∼150 s by a cathodic polarization at −2.1 V vs. saturated mercurous sulfate electrode in a solution of 0.5 M Na2SO4 containing 20 mM Na2SeSO3. It involves continuous autooxidation of Cu to Cu2Se and its electroreduction. The flower-like Cu2Se nanosheets can be further transformed in situ into urchin-like Cu nanowire arrays by cyclic voltammetry for 5∼20 cycles in a solution of 0.1 M NaOH. It undergoes repeated anodization/dissolution and deposition of Cu. The mechanisms for these fast anomalous conversions have been elucidated in detail. The in situ formed urchin-like Cu nanowire arrays from the flower-like Cu2Se can serve as an advanced glucose sensor, which possesses these merits of high sensitivity (3745 μA mM−1 cm−2), low detection limit (0.51 μM), wide linear range (up to 6.11 mM), long-term stability (remaining 90.5% of its initial current response for a 12-week storage), excellent reproducibility (RSD < 5%), and reliable accuracy (with a recovery of 101%).