Preparation of a Pt thin-film modified electrode for alkaline electrocatalytic oxidation of methanol by Cu(OH)2 electrodeposition and galvanic replacement reaction

Abstract

Improving the utilization and anti-poisoning ability of Pt for electrocatalysis applications is widely concerned for years. Herein, a Pt thin-film modified electrode is prepared via a galvanic replacement reaction (GRR) of the copper thin film originated from directly electrodeposited Cu(OH)2 for high-performance electrocatalytic oxidation of methanol in alkaline medium. In an unbuffered electrolyte solution of CuSO4 and p-benzoquinone (BQ), a uniformly distributed Cu(OH)2 thin-film is deposited on a gold-plated glassy carbon electrode (Au/GCE) by electroreducing BQ to consume H+ near the electrode surface. The electroreduction of Cu(OH)2 to atomic copper and then its GRR with K2PtCl4 yields a Pt thin-film modified Au/GCE (PtCu(OH)2/Au/GCE) with excellent performance for electrocatalytic oxidation of methanol in alkaline medium. The processes and mechanisms of electrode modification are investigated by electrochemistry, quartz crystal microbalance, scanning electron microscopy and energy-dispersive spectroscopy. Under the optimal conditions, the electrocatalytic oxidation peak current obtained by cyclic voltammetry (−0.8 V～0.8 V, 50 mV s−1) on PtCu(OH)2/Au/GCE is 21.8 mA cmPt−2 in 0.5 M aqueous KOH containing 1 M methanol. The method is expected to be a good candidate for electrodepositing other uniform films for wider applications.