Room-Temperature Pulsed Laser Deposition of Boron Nitride for Enhanced Fuel Cell Selectivity

Hydrogen fuel cells based on proton exchange membrane (PEM) technology are promising as an alternative to fossil fuel-based energy. However, current membrane technology suffers from hydrogen crossover, which represents a significant loss of efficiency. In this work, we demonstrate a scalable, room-temperature coating of ultrathin, polycrystalline boron nitride (BN) via pulsed laser deposition (PLD) that simultaneously increases the conductivity of perfluorosulfonic acid (PFSA)-based membranes while decreasing the crossover, retaining hydrogen on the anode. BN-coated membranes show a 20% increase in beginning of life performance at the operational conditions (1.485 A/cm 2 at 0.6 V) and a 20% increase in power density (0.965 W/cm 2 ) while exhibiting a maximum crossover current decrease of 32% (3.58 mA/cm 2 ) relative to industry standard Nafion NR-211. The room-temperature direct deposition of ultrathin boron nitride with the PLD method onto a polymer membrane stands as a significant improvement to traditional 2D material transfer-based methods. These observations are practically relevant for the development of PEM technology by enabling more scalable and cost-effective high-performance fuel cell stacks.