RhNi Bimetallenes with Lattice‐Compressed Rh Skin towards Ultrastable Acidic Nitrate Electroreduction

Abstract Harvesting recyclable ammonia (NH₃) from acidic nitrate (NO₃⁻)‐containing wastewater requires the utilization of corrosion‐resistant electrocatalytic materials with high activity and selectivity towards acidic electrochemical nitrate reduction (NO₃ER). Herein, ultrathin RhNi bimetallenes with Rh‐skin‐type structure (RhNi@Rh BMLs) are fabricated towards acidic NO₃ER. The Rh‐skin atoms on the surface of RhNi@Rh BMLs experience the lattice compression‐induced strain effect, resulting in shortened Rh–Rh bond and downshifted d‐band center. Experimental and theoretical calculation results corroborate that Rh‐skin atoms can inhibit NO₂*/NH₂* adsorption‐induced Rh dissolution, contributing to the exceptional electrocatalytic durability of RhNi@Rh BMLs (over 400 h) towards acidic NO₃ER. RhNi@Rh BMLs also reveal an excellent catalytic performance, boasting a 98.4% NH₃ Faradaic efficiency and a 13.4 mg h⁻¹ mg_cat⁻¹ NH₃ yield. Theoretical calculations reveal that compressive stress tunes the electronic structure of Rh skin atoms, which facilitates the reduction of NO* to NOH* in NO₃ER. The practicality of RhNi@Rh BMLs has also been confirmed in an alkaline‐acidic hybrid zinc‐nitrate battery with a 1.39 V open circuit voltage and a 10.5 mW cm⁻² power density. This work offers valuable insights into the nature of electrocatalyst deactivation behavior and guides the development of high‐efficiency corrosion‐resistant electrocatalysts for applications in energy and environment.