Synergetic Effect of Ni-Substituted Pd2Ge Ordered Intermetallic Nanocomposites for Efficient Electrooxidation of Ethanol in Alkaline Media

Abstract

Development of highly active and stable low-cost Pt-free catalysts for ethanol electrooxidation (EOR) in alkaline medium has drawn a lot of attention in recent years. Palladium-based catalysts are on the forefront of this research. Pd2Ge, previously developed by our group, is a highly active and stable catalyst for EOR because of its ordered structure and the presence of Ge. In this work, we used it as a platform to further enhance its efficiency by Ni substitution (Pd2–xNixGe), which shifts the d-band center of the catalysts toward the Fermi level with the increasing binding energy toward the adsorbate. Stronger interaction between the Ni, Pd, and Ge atoms leads to stronger adsorption of −OH intermediates (−436 kJ/mol) and weaker adsorption of −CH3CO (−220 kJ/mol). As a result, this catalyst exhibits 3.8 times higher mass activity and 70 mV lower onset potential than pristine Pd2Ge for EOR in alkaline media.