Graphdiyne‐Stabilized Cobalt Oxyhydroxide Quantum Dots for Efficient Nitrate‐to‐Ammonia Electrocatalysis

The electrocatalytic nitrate reduction reaction (NtRR) offers a sustainable and promising alternative to the energy‐intensive Haber–Bosch process for ambient ammonia (NH 3 ) synthesis. However, its practical application is limited by sluggish reaction kinetics and low selectivity due to competing side reactions. Herein, we demonstrate the in situ transformation of cobalt oxyhydroxide (CoOOH) nanosheets into a well‐defined quantum dot (QD) architecture induced by a graphdiyne (CoOOH@GDY). Experiments combined with theoretical results demonstrate that the noninteger charge transfer between sp‐C and Co atoms at the interface enables precise electronic modulation, the formation of abundant low‐coordination sites and grain boundaries, optimized adsorption ability for reaction intermediates, and high intrinsic catalytic activity. As a result, the obtained CoOOH@GDY electrocatalyst exhibited exceptional NtRR performance, achieving a remarkable Faradaic efficiency of 98.01%, a high NH 3 yield rate of 1644 µmol h −1 cm −2 in 1 M KOH with 0.1 M NO 3 − , and high operational stability. This work highlights the great potential of GDY‐mediated interface engineering for the rational design of high‐performance electrocatalysts.