One-pot synthesis of PdAuAg nanocrystals for efficient electrocatalytic oxidation of ethanol: achieving morphology control by independently adjusting metal-atom concentrations

Abstract

Morphology control is widely acknowledged as an effective method for optimizing the exposed facets and active sites of palladium (Pd) nanocrystals, which enhances their electrocatalytic activity. However, conventional approaches inevitably alter the reaction from both thermodynamic and kinetic perspectives, rendering control intricate. In this investigation, we introduce a specialized strategy to achieve morphology control over PdAuAg nanocrystals, demonstrating their exceptional performance as electrocatalysts for the ethanol oxidation reaction (EOR). Specifically, three metallic precursor solutions were individually introduced into a one-pot reaction system at controlled rates using syringe pumps, allowing for separate manipulation of each metal atom's concentration without cross-reaction. Consequently, a variety of products with unique morphologies and structures were produced, all adhering to the same protocol except for the rate of metal atom introduction. When catalyzing the EOR, the optimized PdAuAg nanocrystals supported on carbon black exhibited a sevenfold increase in mass activity compared to Pt/C, as well as enhanced reaction kinetics and long-term stability. Density functional theory (DFT) calculations confirmed that crystal facets can influence the ethanol oxidation reaction pathway, rationalizing the improved catalytic performance. Our study presents a viable approach for modulating the morphology of trimetallic nanocrystals by varying the feed rate of metal atoms in a one-pot reduction, illuminating the rational design of high-performance fuel cell catalysts.