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.