Improved methanol oxidation activity and stability of well-mixed PtRu catalysts synthesized by electroless plating method with addition of chelate ligands

A new synthetic scheme of PtRu catalysts for methanol oxidation reaction is reported. P containing PtRu nanoparticles 2 nm in size were synthesized by electroless plating method using phosphinic acid as a reducing agent as well as the source of P. Chelate ligands were added in the synthetic system to decrease the difference of effective reduction potentials between Pt4+ and Ru3+ cations in their chloride precursors. Coordination ability of the chelate ligands with the cations was evaluated using UV-vis spectroscopy. It was found that DL-tartaric acid has the highest coordination ability with the cations and that the difference decreases from 0.4 to 0.19 V with addition of DL-tartaric acid. Microstructure, bulk and surface compositions of the PtRu catalysts were analyzed by means of XRD, XRF and Cu stripping voltammetry techniques, respectively. Results revealed that Pt and Ru atoms are well mixed and that both bulk and surface compositions are close to Pt50Ru50 in PtRu catalyst synthesized with DL-tartaric acid. The well-mixed PtRu catalyst synthesized with DL-tartaric acid showed higher methanol oxidation reaction activity and stability values relative to those of PtRu catalyst synthesized without DL-tartaric acid. (C) 2010 Elsevier B.V. All rights reserved.