Nitrate-to-Ammonia Conversion at an InSn-Enriched Liquid-Metal Electrode

Abstract

The renewable energy driven electrochemical conversion of nitrates to ammonia is emerging as a viable route for the creation of this hydrogen carrier. However, the creation of highly efficient electrocatalysts that show prolonged stability is an ongoing challenge. Here we show that room temperature liquid metal Galinstan can be used as an efficient and stable electrocatalyst for nitrate conversion to ammonia achieving rates of up to 2335 μg h−1 cm−2 with a Faradaic efficiency of 100 %. Density functional theory (DFT) calculations and experimental observation indicated the activity is due to InSn alloy enrichment within the liquid metal that occurs during the electrocatalytic reaction. This high selectivity for NH3 is also due to additional suppression of the competing hydrogen evolution reaction at the identified In3Sn active site. This work adds to the increasing applicability of liquid metals based on Ga for clean energy technologies.