(Invited) Composition Dependent Performance of Au-Pd Core-Shell Nanocatalysts for CO₂ Electrochemical Reduction

Abstract

Electrochemical reduction of CO 2 (CO 2 RR) to produce valuable chemicals is promising in simultaneously controlling the CO 2 concentration and storing renewable energy. However, its wide adoption still needs highly selective and reactive catalysts. In this study, Au-Pd core-shell (CS) nanoparticles consisting of a Au-rich core and Pd-rich shell were synthesized by wet methods. The nanoparticle composition and shell thickness were adjusted to evaluate their impacts on CO 2 -to-CO electrocatalytic conversion performance. The CS nanoparticles have a uniform morphology with an average size between 7 to 9 nm. As compared to pure Pd and Au nanoparticles with a similar size, all the synthesized CS nanoparticles exhibited a significantly increased CO selectivity (Figure 1). The CS nanoparticles also have superior mass and specific activities, which are highly dependent on the composition and structure. The best catalyst showed an ultrahigh mass activity of 99.8 mA mg -1 at -0.5 V along with a superior CO faradaic efficiency of 94.7%. In situ infrared spectroscopic studies with an attenuated total reflection configuration (ATR) and density functional theory calculations (DFT) were conducted to reveal the combined structure and composition impacts on the activity. It was found that the scaling relation between *COOH and *CO binding strength was broken on the core-shell nanoparticles and led to the high selectivity and activity toward CO production. The authors acknowledge the support from Hong Kong Research Grant Council (26206115 and 16309418). Figure 1. Faradaic efficiency of CO measured on synthesized Au-Pd core-shell, Pd and Au nanoparticles. Figure 1