Tuning the electronic structure of Ag-Pd alloys to enhance performance for alkaline oxygen reduction

José A Zamora Zeledón,Michaela Burke Stevens,Christopher Hahn,Alessandro Gallo,Jens K Nørskov,Alan T Landers,Melissa E Kreider,G T Kasun Kalhara Gunasooriya,Thomas F Jaramillo

doi:10.1038/s41467-021-20923-z

José A Zamora Zeledón, Michaela Burke Stevens + Show 7 more

Open Access

https://doi.org/10.1038/s41467-021-20923-z

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Abstract

Alloying is a powerful tool that can improve the electrocatalytic performance and viability of diverse electrochemical renewable energy technologies. Herein, we enhance the activity of Pd-based electrocatalysts via Ag-Pd alloying while simultaneously lowering precious metal content in a broad-range compositional study focusing on highly comparable Ag-Pd thin films synthesized systematically via electron-beam physical vapor co-deposition. Cyclic voltammetry in 0.1 M KOH shows enhancements across a wide range of alloys; even slight alloying with Ag (e.g. Ag0.1Pd0.9) leads to intrinsic activity enhancements up to 5-fold at 0.9 V vs. RHE compared to pure Pd. Based on density functional theory and x-ray absorption, we hypothesize that these enhancements arise mainly from ligand effects that optimize adsorbate–metal binding energies with enhanced Ag-Pd hybridization. This work shows the versatility of coupled experimental-theoretical methods in designing materials with specific and tunable properties and aids the development of highly active electrocatalysts with decreased precious-metal content.

Highlights

Alloying is a powerful tool that can improve the electrocatalytic performance and viability of diverse electrochemical renewable energy technologies
Hydrogen fuel cells (FCs) (H2 FCs) are interesting because H2 is an abundant commodity already produced at a large scale as an industrial chemical feedstock (~60 Mt y−1)[2]
H2 FC vehicles are attractive for both light-duty and heavy-duty transportation as they can be refueled in minutes and provide sufficient energy density to be viable for a broad range of transportation modes including automobiles, trucks, buses, airplanes, and boats[3]

Summary

Introduction

Alloying is a powerful tool that can improve the electrocatalytic performance and viability of diverse electrochemical renewable energy technologies. Using cyclic voltammetry (CV), we investigated the ORR activity as a function of alloy composition by cycling (20 mV s−1) various Ag1–xPdx thin films in 0.1 M KOH using a rotating disk electrode (RDE, 1600 rpm) (Fig. 2a and Supplementary Fig. 7).

Results

Conclusion