Preparation and electrocatalytic application of PdNPs-La_2NiO_4 nanocatalyst for methanol electrooxidation

摘要

A direct methanol fuel cell is a new type of battery that produces electricity from combining fuel and oxygen. In this paper, nanosized La2NiO4 perovskite (La(2)NiO(4)NPs) was synthesized by co-precipitation method and characterized by different techniques such as X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The electrocatalytic activity of modified glassy carbon electrode (GCE) with Pd nanoparticles (PdNPs) and La(2)NiO(4)NPs toward the electrooxidation of methanol were evaluated by cyclic voltammetry and chronoamperometry methods in 1 M NaOH solution. Based on the results, PdNPs-La(2)NiO(4)NPs nanocomposite has remarkable catalytic activity for electrooxidation of methanol compared to PdNPs and La(2)NiO(4)NPs. The results also showed, the presence of La(2)NiO(4)NPs in the proposed nanocomposite decreases the poisoning rate of PdNPs with by-products resulted from oxidation reaction of methanol. In addition, the effects of some factors such as methanol concentration, NaOH concentration and temperature on the anodic current densities were studied. The coefficient of electron transfer (alpha) and current densities ratio (I-f/I-b) for methanol electrooxidation on the surface of GC/PdNPs-La(2)NiO(4)NPs electrode were estimated as 0.68 and 1.87, respectively. A direct methanol fuel cell was developed with PdNPs-La(2)NiO(4)NPs nanocomposite and a maximum power density of 12.74 mW.cm(-2) was reached at methanol concentration of 1 M and 70 degrees C.