Polymer-confined synthesis of gram-scale high-entropy perovskite fluoride nanocubes for improved electrocatalytic reduction of nitrate to ammonia.

High-entropy perovskite fluoride (HEPF) has gradually attracted attention in the field of electrocatalysis due to its unique properties. Although traditional co-precipitation methods can efficiently produce HEPF, the resulting catalysts often lack regular morphology and tend to aggregate extensively. Here, nanocubic K(CuMgCoZnNi)F₃ HEPF (HEPF-2) was successfully prepared on a gram-scale by a polyvinylpyrrolidone (PVP)-confined nucleation strategy. Benefiting from its large electrochemically active surface area and well-exposed active sites, the HEPF-2 demonstrates dramatically enhanced electrocatalytic activity in electrocatalytic nitrate reduction to ammonia, leading to an improved ammonia yield rate (7.031 mg h^-1 mg_cat.^-1), a high faradaic efficiency (92.8%), and excellent long-term stability, outperforming the irregular HEPF nanoparticles (HEPF-0) prepared without the assistance of PVP. Our work presents an efficient and facile method to synthesize perovskite fluorides with a well-defined structure, showing great promise in the field of high-performance electrocatalysis.