Strategies for mitigating phosphoric acid poisoning to enhance HT-PEMFC performance: Review and perspectives

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) offer significant advantages for clean energy conversion. However, their performance is severely hindered by the dual role of phosphoric acid (PA), which serves as the proton conductor but also acts as a potent poison for platinum (Pt) catalysts, inhibiting the oxygen reduction reaction (ORR) and demanding high Pt loadings. This review provides a systematic analysis of the extensive efforts to mitigate PA poisoning. A diverse range of strategies is surveyed, including the development of poison-tolerant Pt-alloy catalysts (e.g., Pt–Ni, Pt–Co), the use of advanced carbon and metal oxide supports to leverage strong metal-support interactions, the design of protective surface modifications, the exploration of Pt-free catalysts like Fe–N–C, and the engineering of the catalyst layer with functional additives. Despite significant progress at the catalyst level, a critical performance gap persists between lab-scale tests and real-world membrane electrode assemblies (MEAs). This discrepancy arises because particle-centric approaches often neglect the severe mass transport limitations and low catalyst utilization within conventional, randomly structured electrodes flooded with viscous PA. To overcome these challenges, a paradigm shift is necessary. It is proposed that the future of HT-PEMFCs lies in a holistic approach that integrates advanced catalyst design with the fabrication of 3D ordered electrode architectures. These engineered structures create efficient transport pathways, maximize the functional triple-phase boundary, and can finally unlock the full potential of poison-tolerant catalysts, enabling high performance with drastically reduced Pt loadings. • Reviews diverse strategies against PA poisoning in HT-PEMFCs. • Summarizes catalyst-level strategies to mitigate PA poisoning. • Identifies RDE-to-MEA performance gap and its root causes. • Proposes integrating catalyst design with 3D ordered electrode architectures.