y An Efficient Direct Ammonia Fuel Cell for Affordable Carbon-Neutral Transportation

Alternative carbon-neutral synthetic fuels are needed to decarbonize the transportation sector, bridging the gap between batteries and biofuels. Herein, we analyze the economics of hydrogen-, nitrogen-, and carbon-based fuels made by carbon-neutral pathways in a post-fossil world where only water, air, and renewable electricity are available for fuel synthesis. We find that ammonia has the lowest source-to-tank energy cost by a significant margin. With this technoeconomic analysis as motivation, we demonstrate a direct ammonia fuel cell (DAFC) prototype with a peak power density of 135 mW cm(-2) The DAFC employs an ammonia-tolerant precious-metal-free cathode catalyst and a high-temperature-stable hydroxide exchange membrane.