Electrochemical Promotion of Bimetallic Palladium-Cobalt Nano-Catalysts for Complete Methane Oxidation

Abstract

The catalytic activity and electrochemical promotion of catalysis (EPOC) of the bimetallic Pd−Co nanoparticles (10 nm) deposited on yttria-stabilized zirconia were investigated for complete methane oxidation. The reaction was conducted under open-circuit and under polarization in a temperature range of 320–400 °C in reducing, stoichiometric, and oxidizing conditions. The catalytic activity of the catalyst nanoparticles increased to 40 % upon positive polarization in all gaseous compositions. A comparison of three reaction conditions revealed that the highest reaction rate increase (enhancement ratio, ρ=1.4) occurs under reducing conditions. The reaction rate increased upon anodic polarization, resulting in non-Faradaic electrochemical modification of catalytic activity (Λ≫1) in reducing and oxidizing conditions and Faradaic or electrochemical enhancement (Λ<1) in stoichiometric reaction condition. This work demonstrates that the formation of different Pd and Co oxide phases can be accurately controlled by electrochemical stimuli and, in reducing conditions, result in pseudo-capacitor behaviour.