Catalytic Advantages, Challenges, and Priorities in Alkaline Membrane Fuel Cells

TLDR

Anion exchange membrane fuel cells have improved performance yet still rely on high platinum‑group‑metal loadings, limiting their competitiveness with proton‑exchange‑membrane fuel cells. The authors aim to identify pathways toward low‑cost, PGM‑free catalysts for both electrodes. They review promising strategies for PGM‑free oxygen reduction and hydrogen oxidation catalysts and outline key challenges for high‑performance, durable electrodes.

Abstract

Recently, anion exchange membrane fuel cells (AEMFCs) have seen a significant growth in research and practical interest as the achievable current density, peak power density, and longevity of state-of-the-art cells have improved dramatically. Though these advances in performance have been important for demonstrating the feasibility of the technology, nearly all AEMFCs reported in the literature have required a relatively high loading of platinum group metal (PGM)-based catalysts at both the anode and cathode electrode to achieve even adequate, let alone exemplary, performance. However, in order to take command of the low-temperature fuel cell market, AEMFCs cannot simply reach the same performance as incumbent proton exchange membrane fuel cells (PEMFCs), which have had decades of development and investment. AEMFCs must be able to realize their most widely quoted advantage over PEMFCs and be produced at a much lower cost than PEMFCs. In the long run, the most likely pathway to acceptably low cost AEMFCs will involve the deployment of PGM-free catalysts at both electrodes. In this Viewpoint, we will discuss what we believe are the most promising approaches to achieve PGM-free catalysts for the oxygen reduction reaction (AEMFC cathode) and hydrogen oxidation reaction (AEMFC anode), as well as provide our perspective on key issues that must be addressed to craft these catalysts into high-performing, durable electrodes.