Ruco Alloy Nanoparticles as Efficient and Durable Electrocatalysts for Oxygen Reduction Reaction in Acidic Medium

The developments of Pt-free catalysts for oxygen reduction reaction (ORR) are great issues to meet the cost challenges of proton exchange membrane fuel cell (PEMFC) commercial applications. In this work, NaBH 4 reduction method was used to synthesize series RuCo/C catalysts. X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) prove that single phase RuCo(3:1), RuCo(2:1), RuCo(1:1), RuCo(1:2) and RuCo(1:3) nanoparticles with an average size of 30 nm are obtained. Cyclic voltammograms (CV) and linear sweep voltammograms (LSV) tests indicate that RuCo(2:1) catalyst has the optimal ORR properties in 0.5 M H 2 SO 4 solution, which benefit from the high alloying degree proved by X-ray photoelectron spectroscopy (XPS) measurements. The addition of Co into RuCo/C catalysts results in an increase of d-band holes of Ru and improves the O 2 adsorb ability at the reaction active sites. Additionally, the RuCo(2:1)/C catalyst shows superior stability after tests for 1000 cycles compared with the Pt/C. These research results reveal that RuCo(2:1) shows great promise as a Pt-free ORR catalyst with high activity, high stability and low cost for PEMFCs