Rare earth cuprates as electrocatalysts for methanol oxidation

A series of rare earth cuprates with overall composition Ln(2-x)M(x)Cu(1-y) M ' O-y(4-delta) (where Ln = La and Nd; M = Sr, Ca and Ba; M ' = Ru and Sb: 0.0 less than or equal to x less than or equal to 0.4 and y = 0.1) have be en tested as anode electrocatalysts for methanol oxidation. The evaluation of electrode kinetic parameters was made galvanostatically. The catalyst ch aracterization was carried out by specific conductivity measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Iodometry. T hese materials exhibit significant activity for methanol oxidation at highe r potentials. The linear correlation between Cu(3 +) content and methanol o xidation activity suggests that the active sites for adsorption of methanol is Cu(3 +). The methanol oxidation onset potential depends on the ease of Cu(2 +) --> Cu(3 +) oxidation reaction. These materials show better toleran ce towards the poisoning by the intermediates of methanol oxidation compare d to that of conventional noble metal electrocatalysts (supported and bulk) . The lattice oxygen in these oxides could be considered as active oxygen t o remove CO intermediates of methanol oxidation reaction. (C) 2001 Elsevier Science B.V. All rights reserved.