Recent Advances in Electrocatalysts for Proton Exchange Membrane Fuel Cells and Alkaline Membrane Fuel Cells

Abstract

kinetics of ORR is around five orders of magnitude slower than that of HOR, thereby requiring a much higher Pt loading in the cathode along with more active and durable ORR electrocatalysts than pure Pt catalysts. [1] This requirement presents challenges for the development of advanced cathode catalysts with lower cost, higher activity and higher durability than Pt. Meanwhile, traditional alkaline fuel cells (AFCs) working on concentrated 30−45% KOH electrolytes gained little attention for decades mainly due to their high sensitivity to atmospheric CO 2 . [2,3] The OH − ions in the electrolyte react with CO 2 and form K 2 CO 3 , which can precipitate out as solid crystals, blocking pores in the electrode and gas diffusion layer. In addition, the consumption of OH − reduces the conductivity of the electrolyte. This issue is addressed by replacing KOH solution with a solid anion exchange membrane (AEM) without mobile cations. An AMFC offers several important advantages over PEMFCs, including: 1) low dissolution rates of catalysts, allowing the use of less expensive Pt-free electrocatalysts; 2) wide selections of materials and components that are stable at high pH; and 3) inexpensive solid electrolytes that do not need fluorinated ionomers. Despite their promise, AMFCs are still in the early development stage and have not been systematically investigated due to the lack of highly conductive and durable AEMs. The recent development of highly conductive The rapid progress of proton exchange membrane fuel cells (PEMFCs) and alkaline exchange membrane fuel cells (AMFCs) has boosted the hydrogen economy concept via diverse energy applications in the past decades. For a holistic understanding of the development status of PEMFCs and AMFCs, recent advancements in electrocatalyst design and catalyst layer optimization, along with cell performance in terms of activity and durability in PEMFCs and AMFCs, are summarized here. The activity, stability, and fuel cell performance of different types of electrocatalysts for both oxygen reduction reaction and hydrogen oxidation reaction are discussed and compared. Research directions on the further development of active, stable, and low-cost electrocatalysts to meet the ultimate commercialization of PEMFCs and AMFCs are also discussed.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202006292.

Pt-Free Metal Nanocatalysts for the Oxygen Reduction Reaction Combining Experiment and Theory: An Overview

“…Molecules 2021, 26, 6689 2 of 15 material has various disadvantages such as low availability, high cost and limited activity/durability [8,9]. That is why the design of novel nanocatalysts with high catalytic activity and stability as well as cost-effective production is very relevant to achieve largescale commercialization of the PEMFCs [11][12][13][14][15]. So far, outstanding efforts have been developed to design more active, stable and cheaper nanocatalysts for the ORR in acid media.…”

Synthesis of Tailored Perfluoro Unsaturated Monomers for Potential Applications in Proton Exchange Membrane Preparation

“…In the last few years, scientists have focused their attention on the development of new catalytic systems with the aim of reducing costs through the enhancement of the performance of the catalyst, by lowering the amount of noble metal (essentially Pt) [9] or Molecules 2021, 26, 5592 2 of 17 by using less expensive metals [8,[10][11][12]. Nevertheless, only a few efforts have been made in the direction of finding a valid alternative to Nafion ® [5,13,14].…”

Intermetallic Platinum Alloy Nanoparticles and Single Atoms Hybrid Electrocatalysts for Proton Exchange Membrane Fuel Cells

“…On the other hand, carbon-based Pt group metal (PGM)-free ORR electrocatalysts consisting of highly dispersed transitionmetal single atoms in nitrogen-coordinated carbon surfaces (Me-N-C) are promising candidates to replace Pt 5 . Unfortunately, the poor durability of Me-N-C has limited their practical applications 9 . Recently, Liu et al reported a hybrid catalyst consisting of Pt-Co alloy nanoparticles supported on Co-N-C with an unprecedented ORR activity (1.77 A mg Pt −1 at 0.9 V) 10 .…”