Electron and Hydrogen Dual Spillover at CeO 2 /Fe 3 C Interfaces for Efficient NH 3 Electrosynthesis and High‐Performance Zn‐NO 3 − Batteries

ABSTRACT The electrocatalytic nitrate reduction reaction (NO 3 RR) offers a sustainable route for ambient ammonia synthesis but is hindered by insufficient active hydrogen ( * H) supply and strong adsorption of oxygen‐containing intermediates. Herein, we propose an electron‐ and hydrogen‐dual‐channel interfacial engineering strategy by constructing a heterojunction of grain‐boundary‐rich CeO 2 intimately interfaced with Fe 3 C on nickel foam (CeO 2 /Fe 3 C@NF). Oxygen‐vacancy‐rich CeO 2 with reversible Ce 3+ /Ce 4+ redox pairs serves a dual function: it donates electrons to Fe 3 C, downshifting the d‐band center of Fe sites to weaken intermediate adsorption and mitigate surface poisoning; and it facilitates water dissociation to generate * H, which spills over onto Fe 3 C to ensure adequate * H supply for hydrogenation. Benefiting from this dual spillover mechanism, CeO 2 /Fe 3 C@NF achieves an exceptional NH 3 electrosynthesis rate of 1.343 mmol h −1 cm −2 with a Faradaic efficiency of 97.04% at −0.3 V vs. RHE in an H‐type cell, ranking among the best non‐precious NO 3 RR electrocatalysts. Furthermore, a rechargeable Zn‐NO 3 − battery using CeO 2 /Fe 3 C@NF as the cathode delivers a power density of 8.93 mW cm −2 and stable operation over 100 h. This work establishes an electron‐ and hydrogen‐dual‐channel paradigm for rational design of efficient NO 3 RR electrocatalysts.