Electrochemical activity of layered double hydroxides supported nano Pt clusters toward methanol oxidation reaction in alkaline solutions

Abstract

Suitable electrode catalyst is a critical factor for the application of direct methanol fuel cell. In this research, layered double hydroxides (LDH) are chosen as the supporting material for platinum to improve its electrochemical activity, tolerance to carbonaceous intermediates as well as reduce the cost of electrode. Experimental results show that low amount of platinum (42 and 29mg/g) can be intercalated into the interlayer of LDH with a thickness less than 1nm, which can effectively enhance the electrochemical activity as well as reduced the cost. Both MgAl-LDH/Pt and NiFe-LDH/Pt have a lower onset potential toward methanol oxidation than commercial 20% Pt/C. In addition, the peak current of NiFe-LDH/Pt is 18.0mA/cm2, which is 1.5- and 4.7-fold higher than that of MgAl-LDH/Pt and commercial 20% Pt/C, respectively. MgAl-LDH/Pt has a higher tolerance to CO poisoning due to its preference to the generation of hydroxyl radical rather than oxygen evolution reaction, which is commonly observed on the surface of NiFe-LDH. By using electrochemical impedance spectroscopy technique, it can be observed that the intercalation of Pt could effectively reduce the electron transfer resistance of LDH.