Controlling fuel crossover and hydration in ultrathin proton exchange membrane-based fuel cells using Pt-nanosheet catalysts

An ultra-thin proton exchange membrane with Pt-nanosheet catalysts was designed for a self-humidifying fuel cell running on H2 and O2. In this design, an ultra-thin Nafion membrane was used to reduce ohmic resistance. Pt nanocatalysts were uniformly anchored on exfoliated, layered double hydroxide (LDH) nanosheets by chemical vapor deposition. After embedding Pt-LDH nanocatalysts in 9 mm-thick Nafion membranes, exfoliated LDH nanosheets effectively captured crossovered H2 and O2 through the membranes. Meanwhile, Pt nanocatalysts on LDH nanosheets catalyzed reactions between captured H2 and O2 and provided in situ hydration inside Nafion membranes to maintain their proton conductivity level. Furthermore, LDH nanosheets reinforced the Nafion membranes, with 181% improvement in tensile modulus and 166% improvement in yield strength. In a hydrogen fuel cell running with dry fuel, the membrane-electrode assembly employing the Pt-LDH/Nafion membrane showed an improvement of 200% in maximum power density, an increase of 197% in current density at 0.3 V and an improvement of 497% in current density at 0.5 V as compared to those with Nafion 211. The Pt-LDH/Nafion membrane with a thickness of 9 μm exhibited a combination of desirable properties for the development of affordable and durable hydrogen fuel cell technology, including better mechanical properties, higher open-circuit voltage, lower ohmic resistance and enhanced water management in a hydrogen fuel cell without external humidification.