Electrocatalysis of methanol at the surface of carbon paste electrode modified with composite of Cu-Al-layered double hydroxide and graphene oxide.

In this work, graphene oxide (GO) was prepared by Hummers' method. Then a composite of Cu-Al-layered double hydroxide (Cu-Al-LDH) and GO was prepared by placing and combining Cu-Al-LDH by co-precipitation method. This composite was used as a modifier of carbon paste electrode (CPE), and their structural characteristics were studied by using X-ray diffraction, Fourier transform infrared, field emission scanning microscopy, energy-dispersive X-ray and Brunauer–Emmett–Teller techniques. The catalytic performance of this modified CPE for methanol oxidation reaction (MOR) in alkaline media was also evaluated by using various electrochemical methods such as cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Comparing the activity of Cu-Al-LDH/GO, Cu-Al-LDH and GO catalysts in CPE for electrocatalysis of MOR in 0.5 M methanol with a scan rate of 50 mV s−1 showed the current densities 2.1 mA/cm2, 0.6 mA/cm2 and 0.33 mA/cm2, respectively. This result indicates that GO provides many active sites and transmission ways to catalyze MOR by creating a high surface area and preventing Cu-Al-LDH accumulation. Also, some effective parameters, such as the percentage of Cu-Al-LDH/GO in the preparation of Cu-Al-LDH/GO/CPE electrode, methanol concentration, the scan rate of potential and switching potential, were investigated in the electrocatalysis of MOR. [ABSTRACT FROM AUTHOR]