Pt Re Electrodes for AEM Water Electrolysis: Catalytic Insights and Performance Optimization for the Hydrogen Evolution Reaction
Authors: Lenhart Brian , Wagner Lindsay , Mckinney Samuel , Ostraat Michele 
Published: December 2024

The urgent global imperative to mitigate climate change and transition towards sustainable energy sources has propelled the search for cost-effective alternatives to fossil fuels. Green hydrogen, produced via water electrolysis powered by renewable energy, stands as a promising solution in this endeavor. However, for green hydrogen to become a viable competitor to fossil fuels, it is crucial to drive down production costs. One promising avenue is thrifting precious group metal (PGM) electrocatalysts with more abundant and cost-effective metals, thereby reducing the overall cost of hydrogen production. In this context, the replacement, alloying, and thrifting of PGM materials hold significant potential. By leveraging cheaper and earth-abundant metals such as rhenium (Re) (currently, $2,000/Kg) and nickel (Ni) (currently, $20/Kg), respectively, in place of platinum (Pt) (currently, $31,000/Kg), the cost of green hydrogen production can be brought to a level that competes with fossil fuel prices [1], [2], [3]. This shift not only fosters sustainability but also reshapes global energy markets, steering them away from carbon-emitting sources towards clean, carbon-free alternatives like hydrogen. In this study, we explore the deployment of an anion exchange membrane water electrolyzer (AEMWE) cathodic hydrogen evolution reaction (HER) electrocatalyst: PtRe dispersed on a porous carbon support alloy (PtRe/C) as a potential replacement for conventional Pt on carbon (Pt/C) catalysts. We investigate two different loadings of PtRe/C (40-10 wt.% PtRe and 25-25 wt.% PtRe/C) and compare their performance against benchmark electrocatalysts, including 50 wt.% Pt/C and 30-3 wt.% PtNi/C. Through a comprehensive analysis involving X-ray Diffraction (XRD), Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy (SEM-EDS), Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES) and electrochemical characterization via Rotating Disk Electrode (RDE), Gas Diffusion Electrode (GDE) half-cell, and Membrane Electrode Assembly (MEA) testing, we demonstrate superior performance of PtRe/C alloys. In-house MEA testing revealed durability of 25-25 wt.% PtRe/C out to 100 h of continuous (steady state) operation at 1 A/cm2 at ~1.8 V with negligible voltage decay. Additionally, 40-10 wt.% PtRe/C performed exceptionally well with durability out to 100 h at 1 A/cm2 and 1.9 V. PtNi/C had the highest overvoltage of 1.95 V at continuous 1 A/cm2. Polarization curves (transient) reveal the best performing catalyst to be 25-25 wt.% PtRe, reaching a overvoltage of 1.7 V at 1 A/cm2 in beginning of life testing while 40-10 wt.% PtRe/C and PtNi/C perform comparably with 1.79 V and 1.83 V at 1 A/cm2 during polarization, respectively. Our findings underscore the potential of alloying and thrifting strategies in advancing the cost-effectiveness and efficiency of green hydrogen production, thereby contributing to the transition towards a sustainable energy future.

References:

[1] F. Vigier, C. Coutanceau, A. Perrard, E. M. Belgsir, and C. Lamy, “Development of anode catalysts for a direct ethanol fuel cell.”

[2] F. Xingxiang et al., “Catalysis of the Electrochemical Oxidation of Formaldehyde and Methanol by Perrhenate Electro-and Electroless Deposition of Rhenium from Reline Deep Eutectic Solvent Communication-A Mechanistic Study on Electrodeposition of Rhenium from Acidic Solution of Ammonium Perrhenate.”

[3] M. F. Azcoaga Chort, V. I. Rodríguez, S. R. de Miguel, and N. S. Veizaga, “Synthesis of PtRe electrocatalysts supported on mesoporous carbon for the ethanol oxidation reaction,” Electrochim Acta, vol. 465, Oct. 2023, doi: 10.1016/j.electacta.2023.142948.