Nanofiber/Nanoparticle Electrodes for Ultra‐low Platinum Fuel Cells via Simultaneous Foam Electrospinning and Electrospraying

ABSTRACT In this study, we developed a new technique, simultaneous foam electrospinning and electrospraying (FE/E), that produces nanofiber/nanoparticle electrodes at higher production rates compared to needle‐based electrospinning and electrospraying (E/E). Herein, the nanofiber amount was precisely controlled by applying various voltages on the foam electrospinning process at a fixed platinum (Pt) loading, which enables an exclusive investigation into the impact of ionomer nanofiber on fuel cell performance at ultra‐low Pt loadings for proton exchange membrane fuel cells. The results show that fuel cell performance is strongly dependent on ionomer nanofiber content. At 0.04 mg/cm 2 nanofiber amount, the electrodes exhibited the highest fuel cell power density of 1.09 W/cm 2 and Pt utilization of 11.5 kW/g Pt , which are 28% and 39% higher than those of the electrode produced via electrospraying alone, respectively. The improvement results from enhanced proton and gas transport stemming from the nanofiber network as verified by cyclic voltammetry, electrochemical impedance spectroscopy, and oxygen gain voltage analysis. The FE/E technique provides a pathway to produce ultra‐low Pt nanofiber/nanoparticle electrodes at high production rates and high fuel cell performance.