Tailoring the d‑Band Center of High‐Entropy Perovskite Oxide Nanotubes for Enhanced Nitrate Electroreduction

Abstract High‐entropy perovskite oxides exhibit promising application prospects in the field of electrocatalysis, owing to their flexible elemental composition, plentiful active sites, and superior structural stability. Herein, high‐entropy perovskite oxide nanotubes are prepared with La, Nd, Pr, Er, Eu at A‐site by electrospinning as efficient electrocatalysts for nitrate reduction reaction (NO 3 RR). Electrochemical tests demonstrate that LaNd 0.25 Pr 0.25 Er 0.25 Eu 0.25 CuO 4 nanotubes (LNPEEC NTs) display outstanding NO 3 RR performance, achieving a NH 3 Faraday efficiency (FE NH3 ) of 100% at −0.7 V versus reversible hydrogen electrode (RHE) and a yield rate NH3 of 1378 µg h −1 mg −1 cat. at −1.0 V RHE , outperforming Nd 2 CuO 4 nanotubes (NC NTs). Furthermore, LNPEEC NTs also exhibit excellent stability even after 10 cycles at −0.7 V RHE and −1.0 V RHE . X‐ray absorption spectroscopy confirms that multi‐component regulation of A‐site optimizes the coordination environment of Cu at B‐site, increasing the unsaturated Cu sites and thus providing more active sites. Additionally, density functional theory calculations reveal that the doping of multi‐component rare‐earth elements at A‐site in LNPEEC NTs modulates the d‐band center of Cu at B‐site and reduces the reaction energy barrier of the rate‐determining step, thus enhancing the adsorption of NO 3 − and promoting the NO 3 RR performance.