Low-cost anion exchange membrane fuel cells have been investigated as a promising alternative to proton exchange membrane fuel cells for the last decade. The major barriers to the viability of anion exchange membrane fuel cells are their unsatisfactory key components—anion exchange ionomers and membranes. Here, we present a series of durable poly(fluorenyl aryl piperidinium) ionomers and membranes where the membranes possess high OH⁻ conductivity of 208 mS cm⁻¹ at 80 °C, low H₂ permeability, excellent mechanical properties (84.5 MPa TS), and 2000 h ex-situ durability in 1 M NaOH at 80 °C, while the ionomers have high water vapor permeability and low phenyl adsorption. Based on our rational design of poly(fluorenyl aryl piperidinium) membranes and ionomers, we demonstrate alkaline fuel cell performances of 2.34 W cm⁻² in H₂-O₂ and 1.25 W cm⁻² in H₂-air (CO₂-free) at 80 °C. The present cells can be operated stably under a 0.2 A cm⁻² current density for ~200 h.

Edge-exposed MoS₂ nano-assembled structures are designed for high hydrogen evolution reaction activity and long term stability. The number of sulfur edge sites of nano-assembled spheres and sheets is confirmed by Raman spectroscopy and EXAFS analysis. By controlling the MoS₂ morphology with the formation of nano-assembled spheres with the assembly of small-size fragments of MoS₂, the resulting assembled spheres have high electrocatalytic HER activity and high thermodynamic stability.