P-Block Antimony–Copper Single-Atom Alloys for Selective Nitrite Electroreduction to Ammonia

Electrocatalytic reduction of NO2– to NH3 (NO2RR) offers an effective method for alleviating NO2– pollution and generating valuable NH3. Herein, a p-block single-atom alloy, namely, isolated Sb alloyed in a Cu substrate (Sb1Cu), is explored as a durable and high-current-density NO2RR catalyst. As revealed by the theoretical calculations and operando spectroscopic measurements, we demonstrate that Sb1 incorporation can not only hamper the competing hydrogen evolution reaction but also optimize the d-band center of Sb1Cu and intermediate adsorption energies to boost the protonation energetics of NO2–-to-NH3 conversion. Consequently, Sb1Cu integrated in a flow cell achieves an outstanding NH3 yield rate of 2529.4 μmol h–1 cm–2 and FENH3 of 95.9% at a high current density of 424.2 mA cm–2, as well as a high durability for 100 h of electrolysis.