Understanding the Electrooxidation of Dimethyl Ether on Pt3Pd3Sn2 Supported on a Mixture of Carbon Materials

Abstract

Recently, we reported a rigorous study on the effect of carbon supports and their cold plasma treatment on a state-of-the-art catalyst, Pt3Pd3Sn2, for dimethyl ether (DME) electrooxidation. The catalyst supported on a mixture of 75% activated multi-walled carbon nanotube (MWCNT) (75 M) and 25% pristine black pearl 2000 (BP2000) (25B) (Pt3Pd3Sn2/75M25B) offered improved DME kinetics with respect to the single or other combinations of the same supports. In this work, the results of the electrochemical impedance spectroscopy (EIS) were coupled with physicochemical characterizations (X-ray Diffraction (XRD), Small Angle X-ray Scattering (SAXS), and Scanning Tunneling Electron Microscopy (STEM)) for a detailed understanding of the origins of the improved kinetics. With an appropriate composition of the two supports in the mixture (75M25B), a catalyst with optimized particle size, dispersion, and conductivity was obtained. A Pt3Pd3Sn2/75M25B-coated electrode exhibited a reduced charge transfer resistance of 0.63 ohms at the catalyst layer compared to BP2000 and MWCNT, which showed 1.53 and 1.31 ohms, respectively. These results provide vital insights into catalyst support design considering the use of support mixtures of optimized conductivity and surface area for enhanced power output.