Fabrication of CuO–1.5ZrO2 composite thin film, from heteronuclear molecular complex and its electrocatalytic activity towards methanol oxidation

Abstract

A heteronuclear coordination complex [Cu₄Zr₆(μ-O)₈(dmap)₄(OAc)₁₂]·H₂O (1), where dmap = N,N-dimethylaminopropanolato and ⁻OAc = acetato, has been isolated in pure form by the chemical interaction of Zr(dmap)₄ with Cu(OAc)₂·H₂O in THF. Complex (1) has been examined by melting point, elemental analysis, FT-IR spectroscopy and single crystal X-ray diffraction. The thermal decomposition behavior of the complex has been explored by thermogravimetric, derivative thermogravimetric and differential scanning calorimetric analyses which reveal that complete conversion of (1) into 1 : 1.5 composite oxides, CuO : ZrO₂, treated at 500 °C. The ability of complex (1) to act as a single-source precursor for the formation of advanced composite oxides thin film has been investigated by aerosol assisted chemical vapor deposition at 550 °C in air ambient. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) analyses of the developed thin films suggest the formation of good quality crystalline microspherical-shaped CuO–1.5ZrO₂ composite oxide with high purity. The electrocatalytic activity of CuO–1.5ZrO₂ composite oxide film was studied toward methanol oxidation in an alkaline medium and it showed high oxidation peak current of 14 μA during a forward scan which is ∼3.5-fold higher than the bare Pt electrode. The ease and low cost fabrication and high electrocatalytic activity of composite oxide film could make it potential candidate for direct methanol fuel cells application.