Proton-Encapsulated Metal-Organic Frameworks for High-Performance Proton Exchange Membranes Operating Across Broad...

Expanding the operating humidity range of proton exchange membrane fuel cells (PEMFC) can effectively enhance their environmental adaptability. However, the proton conductivity of traditional Nafion membranes drops sharply at low humidity, which seriously limits PEMFC performance. In this study, zwitterionic sulfamic acid (SA) was encapsulated in a metal-organic framework MOF-808 (SA@MOF-808) as a functional filler in the Nafion matrix. The hydrophilic groups on the surface and the high porosity of SA@MOF-808 endow it with excellent water retention capacity. The hydrogen-bonded network formed by the sulfonic acid and amino groups in SA establishes a highly efficient proton transport channel. Therefore, the prepared hybrid membrane exhibits significantly enhanced proton conductivity, which is 1.1 times and 1.6 times higher than that of Nafion membrane at 80°C under 95% RH and 40% RH, respectively. Its maximum conductivity reaches 299.60 mS·cm^-1. This study provides an effective strategy for designing high performance PEM for low-humidity environments.