Renewable power-derived green hydrogen distributed via natural gas networks is considered one of the viable routes to drive the decarbonization of transportation and distributed power generation, while a trace amount of sulfur impurities is one of the key factors that affect the durability and life cycle expense of proton-exchange membrane fuel cells (PEMFCs) for end users. Herein, we explore the underlying effect of sulfur resistance for Ptbased hydrogen oxidation reaction (HOR) electrocatalysts devoted to high-performance and durable PEMFCs. Two typical electrocatalysts, Pt/C with pure Pt nanoparticles (NPs) and PtCo/C with Pt 3 Co-alloy-core-Pt-skin NPs, were investigated to demonstrate the structure−property relation for Pt-based electrocatalysts. It was revealed that the PtCo/C demonstrated alleviated sulfur poisoning with the adsorption rate constant reduced by 21.7% compared with Pt/C, and the desorption of the adsorbed sulfur was also more favorable with Pt−S bond decomposition temperature lowered by approximately 25 °C. Characterization indicated that sulfur was predominantly adsorbed in the edge mode for PtCo/C, but in a comparable edge and bridge mode for Pt/C, which caused the strengthened Pt−S binding by the chelation effect for Pt/C. The lowered d-band center of surface Pt for PtCo/C, tuned by electron transfer from Co to Pt and Pt lattice strain, was also found responsible for the weakened Pt−S interaction. The recovery test based on electro-oxidation suggested that PtCo/C also outperformed Pt/C with faster and more thorough release of HOR active sites. The SO 42− species derived from electro-oxidation of S 2− was more apt to adsorb on Pt/C than PtCo/C because of its stronger affinity to SO 4 2− caused by the higher d-band center of Pt. Therefore, it is clarified that adequate modification of the Pt d-band center, for example, negatively tuned for the state-of-the-art Pt/C, is crucial to improve the sulfur resistance and recovery capability for Pt-based electrocatalysts while reserving comparable HOR activity. In particular, the investigated PtCo/C electrocatalyst is a better choice over Pt/C for more durable PEMFC anodes.

Exploring cost-effective non-precious metal electrocatalysts is vital for the large-scale application of clean energy conversion devices (i.e., fuel cells, metal-air batteries and water electrolyser). Herein, we present the construction of...

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.

Assurance of high-quality hydrogen is critical for end usage in proton-exchange membrane (PEM) fuel cell (PEMFC) electric vehicles with a long lifetime and low cost as a trace amount of CO impurities in hydrogen significantly affects the durability and fuel expense. Herein, we demonstrate an effective strategy to reduce the total ownership cost of PEMFC vehicles by coupling material development and operation optimization, aiming to obtain the optimal tolerance limit for hydrogen impurities. An electrochemical hydrogen pump was used to accurately determine the poisoning-caused overpotential by eliminating interferences from cathode polarization and the permeated oxygen from thin PEM. The quantitative relations of overpotential versus influencing factors (e.g., type of catalysts, CO concentration, and temperature) were established. The results indicate that PtRu/C demonstrates alleviated CO poisoning, exhibiting approximately 12.8 mV lower overpotential than Pt/C after 100 h test (PtRu/C: 6 mV; Pt/C: 18.8 mV) with a CO concentration of 0.2 ppm specified by ISO standards (14687: 2019) and its increase rate of overpotential is reduced to 1/3-fold. Only the electronic effect induced by Pt–Ru interactions is responsible for the improved CO tolerance of PtRu/C under ultra-low CO concentrations, whereas the widely recognized bi-functional effect due to the reaction of Ru–OH with neighboring Pt–CO species does not work, leading to over 10% decrease of CO–Pt(111) adsorption energy for PtRu/C compared with Pt/C. By means of the synergistic effect of the alternative PtRu/C catalyst and an elevated cell temperature at 85 °C, the CO limit can be loosened to 25-fold from currently recommended 0.2 to 5 ppm, which will remarkably decrease the cost of hydrogen purification. This work offers an insight for the cost reduction of hydrogen mobility and the future optimization of hydrogen quality and also provides valuable guidance for the design of robust anti-poisoning CO catalysts for the long-term application of PEMFCs.

The anode feed for hydrogen fuel cell electric vehicles (FCEVs) currently still relies on the reformed fuel that inevitably contains contaminants (e.g., CO, H 2 S, and NH 3 ). As one of the most sensitive impurities, trace H 2 S in hydrogen significantly deteriorates the durability of proton exchange membrane fuel cells (PEMFCs), while there is still a lack of effective strategies to mitigate H 2 S poisoning in PEMFCs. Herein, we present two kinds of facile, operatable, and efficient strategies to mitigate a H 2 S-poisoned anode, with the aim of improving the durability of PEMFCs by releasing more Pt reactive sites for hydrogen oxidation reaction (HOR) catalysis. The first mitigation strategy is conducted by increasing the cell temperature temporarily when purging with pure hydrogen after H 2 S poisoning by means of accelerating H 2 S desorption on Pt sites under high temperatures and thus releasing more available Pt reactive sites for HOR catalysis. A higher temporary temperature leads to a larger recovery percentage of performance, outperforming the effect of the generally adopted pure hydrogen purging operation. Another mitigation strategy is called "internal oxygen permeation", based on the oxidation of sulfur-adsorbed anode by compelling air diffusion through thin PEM via constructing a pressure differential between the cathode and the anode. The cell was found to be recovered more at a high pressure differential due to the fact that more sulfur species are oxidized by a larger content of permeated oxygen, showing ∼88.7% performance recovery for 0.40 bar pressure differential. The proposed strategies with simplicity, operability, and resilience show promising potential in the application of long-term PEMFCs, which is critical for the durability improvement of FCEVs and cost reduction of hydrogen purification.