Earth-abundant elements a sustainable solution for electrocatalytic reduction of nitrate

Platinum group elements (PGEs) are widely-used electrocatalysts. However, the low abundance of PGEs in the earth's crust and high environmental impacts to be acquired result in high costs, limiting their use in drinking water treatment. Identifying sustainable alternatives to PGEs is a major barrier in applying electrocatalysis for nitrate reduction. By moving up the periodic table, this study provides a framework for selecting promising earth-abundant elements that can electrocatalytically degrade nitrate in water to innocuous by-products. We benchmarked platinum (Pt) against less-endangered elements for electrodes by quantifying nitrate reduction rates, by-product selectivity, and energy efficiencies. Carbon (as boron-doped diamond) and tin had the highest average selectivity towards nitrogen gas evolution (55 % and 64 %, respectively) outperforming Pt, which only had 1% selectivity, and had comparable electrical energy per order removal of nitrate. Thus, earth-abundant elements for electrocatalysis hold tremendous promise as innovative, low-cost, and sustainable processes for the water treatment marketplace.