The ubiquitous use of ammonia in agricultural nitrogen fertilizers makes it essential to our lives and food availability. However, ammonia’s production comes with an important energetic cost; it is one of the most energy- and emissions-intensive industries as the traditional method to produce ammonia — the Haber–Bosch process — necessitates high temperatures and pressures for the reaction between nitrogen and hydrogen to proceed efficiently and at a commercially viable rate. Electrosynthesis of ammonia using renewable energy sources is a sought-after green alternative. However, large-scale ammonia electrosynthesis requires highly selective and efficient catalysts, which is challenging as catalysts usually facilitate the formation of more than one product. Now, writing in Nature Communications, Guihua Yu and colleagues present the design of highly selective and scalable catalysts to convert nitrate into ammonia under mild conditions with high yield rates.High-entropy materials —typically comprising at least five different elements in equimolar or near equimolar proportions within a lattice structure — have increased configurational entropy, which translates into less ordered structures, with metal elements randomly located. This disorder can help increase the number of catalytic active sites and lower the energy barriers of catalytic reactions. When this concept is combined with the single-atom strategy — where metal atoms are independently distributed and anchored on a host material — the electrocatalytic activity can be further boosted by maximizing the number of active sites. “However, because of the complexity of the interactions between the different elements, making these materials controllably and reliably has been challenging,” comments Yu.
