Intriguing H₂S Tolerance of the PtRu Alloy for Hydrogen Oxidation Catalysis in PEMFCs: Weakened Pt–S Binding with Slower Adsorption Kinetics

Abstract

High quality of hydrogen is the key to the long lifetime of proton-exchange membrane fuel cell (PEMFC) vehicles, while trace H2S impurities in hydrogen significantly affect their durability and fuel expense. Herein, we demonstrate a robust PtRu alloy catalyst with an intriguing H2S tolerance as the PEMFC anode, showing a stronger antipoisoning capability toward hydrogen oxidation reaction compared with the Pt/C anode. The PtRu/C-based single PEMFC shows approximately 14.3% loss of cell voltage after 3 h operation with 1 ppm of H2S in hydrogen, significantly lower than that of Pt/C-based PEMFCs (65%). By adopting PtRu/C as the anode, the H2S limit in hydrogen can be increased to 1.7 times that of the Pt/C anode, assuming that the PEMFC runs for 5000 h, which is conductive for the cost reduction of hydrogen purification. The three-electrode electrochemical test indicates that PtRu/C exhibits a slower adsorption kinetics toward S2– species with poisoning rates of 0.02782, 0.02982, and 0.03682 min–1 at temperatures of 25, 35, and 45 °C, respectively, all lower than those of Pt/C. X-ray absorption fine structure spectra indicate the weakened Pt–S binding for PtRu/C in comparison to Pt/C with a longer Pt–S bond length. Density functional theory calculation analyses reveal that adsorption energy of sulfur on the Pt surface was reduced for PtRu/C, showing 1–10% decrease at different Pt sites for (111), (110), and (100) planes, which is ascribed to the downshifted Pt d-band center caused by the ligand and strain effects due to the introduction of second metallic Ru. This work provides a valuable guide for the development of the H2S-tolerant catalysts for long-term application of PEMFCs.

A spontaneous hydrogen fuel purifier under truly ambient weather conditions

“…It should be noted that Pt–Ru/C has superior H 2 S tolerance than Pt/C and Ni/C, which is due to its slower adsorption kinetics towards S 2− species. 38 With PtRu/C, the polarization curve with H 2 S (1000 ppm H 2 S) exhibited a peak power density of nearly 25 mW cm −2 at a peak current density of nearly 70 mA cm −2 (Fig. 4(b)) which is lower than the performance metrics with pure H 2 fuel (Fig.…”

“…This decay in performance can be attributed to slow poisoning of the platinum electrode by sulphur-containing species. 38 In situ electrochemical mass spectrometry during spontaneous fuel purification of the H 2 -H 2 S mixture (1000 ppm H 2 S) shows the consumption of H 2 in the anodic half-cell (red trace in Fig. 4(d)) and the generation of pure H 2 streams in the cathodic half-cell (green trace Fig.…”

Plasmonic alloys for quantitative determination and reaction monitoring of biothiols

“…S1E, ESI †), readily assigned to Au 4f 7/2 and Au 4f 5/2 of Au 0 from PdPtAu alloys. Considering the high binding affinity between noble metals and thiol groups (e.g., binding energy of 161.8/162.8/162.6 eV for Pd/Pt/Au-S [29][30][31] ), the as-prepared trimetallic alloys showed potential in directly extracting biological thiols from complex clinical biosamples.…”

“…For molecular structure, PdPtAu alloys demonstrated preference targeting thiol-containing molecules, especially biothiols, because of the synergistic affinity resulting from the Au-S bond (binding energy of B162.6 eV) and Pt-S bond (binding energy of B162.8 eV) between PdPtAu alloys and biothiols. 30,31 Notably, the adsorption rate (see the detailed calculation in the detection preference determination) of Cys as measured by LDI MS detection was as high as 13.15 AE 0.87%, by using PdPtAu alloys as both the affinity probe and enhancement matrix (Table S1, ESI †). This adsorption rate was comparable or even better than the value reported in previous literature.…”

Poisoning Mechanism of the CO and H2S Mixture on the Anode of Polymer Electrolyte Membrane Fuel Cell

“…Modeling results have shown that $${{\rm P}{\rm t}-{{\rm S}}_{ads}}$$ formed on the catalyst surface can be oxidized to $${{{\rm S}{\rm O}}_{3}}$$ or $${{{\rm S}{\rm O}}_{4}^{2-}}$$ consuming water, leading to decreased membrane conductivity and S crossover to the cathode, negatively affecting the oxygen reduction reaction and diminishing the PEMFC performance [29,30] . Therefore, efforts have been made to develop PtRu, [31–33] PtCo, [34,35] and PtNi [36,37] alloy catalysts with high resistance to CO and H 2 S to mitigate these poisoning effects. Extensive studies have been conducted on the effects and mechanisms of poisoning caused by CO and H 2 S individually.…”