The performance degradation of proton exchange membrane fuel cells (PEMFCs) is one of the most critical challenges in their practical applications. Degradations of electrocatalysts for oxygen reduction reaction (ORR) at cathode and hydrogen oxidation reaction (HOR) at the anode are the major contributors to PEMFC degradation, which are mainly induced by fuel/air impurities, unintentional harmful species during the preparation and use of the catalysts, as well as catalyst decomposition during the operation. This review summarizes the recent research on PEMFC performance degradation and the progress in developing mitigation strategies for avoiding the degradation. Several aspects are emphasized as follows: the understanding of catalyst poisoning phenomena, influencing factors, and general degradation mechanisms. Several technical challenges are analyzed and the corresponding future research directions are proposed to facilitate the further research and development of mitigation strategies for PEMFC catalyst degradation.

Recent research progress in PEM fuel cell electrocatalyst degradation and mitigation strategies

Efficient and durable gas diffusion electrode for proton exchange membrane fuel cell via in-situ growth of Pt nanowires on dual microporous layer

Ternary platinum (Pt)-based ordered intermetallics represent a group of promising electrocatalysts in energy-conversion applications, because of their multielemental coupling that can potentially boost the activity and durability of the oxygen reduction reaction (ORR). Yet, the achievable catalysis performance is still susceptible to the inevitable transition metal leaching that can hardly be eliminated in an acidic environment. Herein, we report a nitrogen (N)-modified carbon (shell) encapsulated Pt–Fe–Cu ordered intermetallic nanoparticles (core) electrocatalyst for acidic ORR, where the Pt–Fe–Cu core presents a face-centered tetragonal (fct) phase. It is demonstrated that N-doped carbon shells can not only protect Pt–Fe–Cu cores from dissolution, agglomeration, coalescence, and Ostwald ripening but also enable the electronic structure regulation of the central Pt sites through the strong Fe–N coordination. The optimized Pt–Fe–Cu intermetallic with N-doped carbon shells delivers superior ORR activity and is more chemically stable over disordered Pt–Fe–Cu alloy, Pt–Fe–Cu intermetallics without a N-doped carbon shell, and commercial Pt/C, where the achievable ORR mass and specific activities are nearly 5-fold and 4-fold higher than those of commercial Pt/C in the acidic media, respectively. 

Pt–Fe–Cu Ordered Intermetallics Encapsulated with N-Doped Carbon as High-Performance Catalysts for Oxygen Reduction Reaction

Synthesis of Quinary Ptpdniaucu Nanotubes with Ultrahigh Electrocatalytic Activity For Oxygen Reduction Reaction

Synthesis of quinary PtPdNiAuCu nanotubes with ultrahigh electrocatalytic activity for oxygen reduction reaction

Surfactants or capping agents are usually employed to control the shapes and sizes of metal nanowires (NWs). Polyvinylpyrrolidone (PVP) and oleylamine (OAm) are the most common capping agents used in the synthesis of metal nanowires. However, these capping agents bind strongly onto the surface of the nanowires and severely prevent the reactant molecules from entering the active sites. In the present research, a facile acetic acid/NaBH4 treatment technology is reported to effectively remove PVP and OAm from the surface of the co-doped Pt NWs. Interestingly, the morphology of poor crystalline platinum nanowires treated with NaBH4 solution is transformed into nanowire networks (NWNs) with higher crystallinity. Furthermore, in comparison with the commercial Pt/C catalyst, the catalytic activity of co-doped Pt NWNs with clean surfaces shows improvements of up to 4.1 times for mass activity and 5.1 times for specific activity, respectively.

Co‐doped Pt Nanowire Networks with Clean Surfaces for Enhanced Oxygen Reduction Reactions

Hydrogen is a promising substitute for non-renewable fossil fuels. Producing hydrogen fuel by electrolyzing water is an effective strategy to address the growing environmental problems. Platinum (Pt) is still the most active electrocatalyst to catalyze the hydrogen evolution reaction (HER) in alkaline media. Herein, we demonstrate that ultrafine candied haws-shaped PtWNi nanoalloys modified with the Ni species (Nin+) could be formed in the alkaline electroactivation process of PtWNi alloys. Notably, the Ni species (Nin+) promoted the decomposition of water and produced hydrogen intermediates, which were then immediately adsorbed on the surface of Pt and recombined into molecular hydrogen. Moreover, these hydrogen intermediates also enhanced the instability of the HO-H bond, leading to an increase in the total activity.

Jiacheng Zhang

Papers

Co‐doped Pt Nanowire Networks with Clean Surfaces for Enhanced Oxygen Reduction Reactions

Boosting alkaline hydrogen evolution performance with alkaline electro-activated ultrafine candied haws-shaped PtWNi nanoalloys.