Assembling the PdCu/rGO catalysts for methanol oxidation reaction in alkaline media by tuning the electronic structure

Abstract: Direct methanol fuel cells (DMFCs) have attracted extensive attention due to clean, efficient characteristics and portable applications. In this work, a series of PdxCuy/reduced graphene oxide(rGO) catalysts are assembled and the catalytic performances are investigated for methanol oxidation reaction(MOR) in alkaline media. The intrinsic surface electronic structures of the PdxCuy/rGO bimetallic catalysts are also studied to clarify the reaction mechanism. The results reveal that Pd1.2Cu0.2/rGO exhibits superior catalytic activity(1101.58 A gPd-1), 4.2 and 5.2 times higher than those of the commercial PtRu/C and Pd/C catalysts. CO stripping suggests that the onset potential for CO oxidation on the Pd1.2Cu0.2/rGO catalyst is lower than those on the commercial PtRu/C and Pd/C catalysts, implying that the anti-CO poisoning ability is enhanced. Combined with the analysis of X-ray diffraction(XRD), high-resolution transmission electron microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS) and Raman, the enhanced catalytic activity and anti-CO poisoning ability are attributed to the charge transfer and lattice compression between Pd and Cu, which modify the d-band center and weaken the adsorption of CO. Furthermore, a volcano plot is found between the MOR activity and d-band center, indicating that the excellent MOR activity is attributed to the optimal d-band center with the moderate adsorption strength of CO-like intermediates.