Engineering Ru@Pt Core-Shell Catalysts for Enhanced Electrochemical Oxygen Reduction Mass Activity and Stability

Abstract

Improving the performance of oxygen reduction reaction (ORR) electrocatalysts is essential for the commercial efficacy of many renewable energy technologies, including low temperature polymer electrolyte fuel cells (PEFCs). Herein, we report highly active and stable carbon-supported Ru@Pt core-shell nanoparticles (Ru@Pt/C) prepared by a wet chemical synthesis technique. Through rotating disc electrode testing, the Ru@Pt/C achieves an ORR Pt mass-based activity of 0.50 A mgPt−1 at 0.9 V versus the reversible hydrogen electrode (RHE), which exceeds the activity of the state-of-the-art commercial Pt/C catalyst as well as the Department of Energy 2020 PEFC electrocatalyst activity targets for transportation applications. The impact of various synthetic parameters, including Pt to Ru ratios and catalyst pretreatments (i.e., annealing) are thoroughly explored. Pt-based mass activity of all prepared Ru@Pt/C catalysts was found to exceed 0.4 mgPt−1 across the range of compositions investigated, with the maximum activity catalyst having a Ru:Pt ratio of 1:1. This optimized composition of Ru@Pt/C catalyst demonstrated remarkable stability after 30,000 accelerated durability cycles (0.6 to 1.0 V vs. RHE at 125 mV s−1), maintaining 85% of its initial mass activity. Scanning transmission electron microscopy energy dispersive spectroscopy (STEM-EDS) analysis at various stages of electrochemical testing demonstrated that the Pt shell can provide sufficient protection against the dissolution of the otherwise unstable Ru core.

The potential of zero total charge and electrocatalytic properties of Ru@Pt core-shell nanoparticles

“…2 shows cyclic voltammograms (CVs) of the Pt catalyst (above) and the Ru@Pt core-shell catalyst (below) in 0.1 mol dm −3 HClO 4 at a sweep rate of 10 mV s −1 . These CVs are similar to those previously recorded by Tsypkin et al [16], Bernechea et al [46], Yang et al [19], Chen et al [47], and Jackson et al [48] for Ru@Pt core-shell catalysts. Whereas the CV of Pt/C displays two clearly distinguishable peaks related to under-potential deposition of hydrogen (H UPD ) at approximately 0.2 V and below, as is typical for such catalysts [49], the corresponding region for the Ru@Pt catalyst shows considerably less structure.…”

Nanostructured gas diffusion layer to improve direct oxygen reduction reaction in Air-Cathode Single-Chamber Microbial Fuel Cells

“…The commercial GDL, composed by PTFE layer, was directly compared with the new designed nanostructured-GDL. The electrolyte is a water-based solution containing 12mM of sodium acetate, used as organic matter, and other compounds (5.8 mM of ammonium chloride and phosphate buffer saline solution (PBS) [10][11][12]) suitable for the preservation of metabolic activity of microorganisms. Titanium wires were used to ensure a good electrical contact and both anode and cathode were connected with a multichannel data acquisition unit (Agilent 34972 A).…”

Progress towards the ideal core@shell nanoparticle for fuel cell electrocatalysis

“…Jackson and colleagues followed with recent work in which they prepared durable and active Ru@Pt catalysts using a wet chemical method [50]. In their study, the researchers sought to evaluate the impact of varying nanoparticle precursor ratios, finding that the most active catalyst was that prepared with an Ru@Pt ratio of 1:1.…”