A Cobalt−Indium Intermetallic Carbide with Balanced Intermediates Adsorption for Electrocatalytic Nitrate‐to‐Ammonia Conversion.

ABSTRACT The electrocatalytic nitrate reduction reaction (NO ₃ RR) to ammonia (NH ₃ ) offers a promising approach for environmental remediation and production of valuable chemicals. While cobalt (Co)‐based materials are frequently employed as catalysts for NO ₃ RR, they are often limited by the nonequilibrium adsorption of intermediates and competing hydrogen evolution reaction, resulting in unsatisfactory NH ₃ selectivity. To address these limitations, we incorporate indium (In) atoms in an orderly fashion into a Co‐based intermetallic carbide (Co ₃ InC _0.75 ), steering electron transfer from In to Co and substantially improving the NO ₃ RR kinetics. Through a combination of in situ spectroscopic measurements and density functional theory calculations, this study reveals that In incorporation effectively modulates Co catalysts’ adsorption of nitrogen‐containing intermediates ( ^* NO _x ) and protons, transforming Co catalysts from proton‐dominant adsorption to preferential ^* NO _x adsorption. Electrochemical tests confirm that Co ₃ InC _0.75 demonstrates a high NH ₃ yield rate of 9.22 mg h ⁻¹ cm ⁻² at −0.8 V vs. RHE and a peak Faradaic efficiency of 98.1% at −0.5 V vs. RHE. Furthermore, the Zn‐NO ₃ ⁻ battery incorporating Co ₃ InC _0.75 delivers a high‐power density of 17.3 mW cm ⁻² . This work provides an innovative strategy for regulating intermediate adsorption for multi‐step electrochemical reactions.