Enhancement of Nitrate‐to‐Ammonia on Amorphous CeOx‐Modified Cu via Tuning of Active Hydrogen Supply

Abstract The electrochemical nitrate reduction reaction (NO 3 RR) is an environment‐friendly and promising alternative to the conventional Haber–Bosch ammonia synthesis process, which is a complex process of proton‐coupled electron transfer. Hereon, the amorphous CeO x support introduced to construct Cu/a‐CeO x heterostructure is prepared to provide sufficient *H and synergistically catalyze the NO 3 RR. Cu/a‐CeO x achieves a maximum ammonia yield of 1.52 mmol h −1 mg cat −1 . In the flow cell, the NH 3 yield reaches 17.93 mmol h −1 mg cat −1 at 1 A cm −2 , which exceeds most of the state‐of‐the‐art catalysts. In situ X‐ray diffraction (XRD) and in situ Raman observe that the catalyst undergoes structural reconfiguration under operating conditions, thus confirming that Cu 2 O is not the true active center in the catalytic process. Furthermore, in situ characterizations and density functional theory (DFT) calculations demonstrate that the amorphous CeO x in Cu/a‐CeO x modulates the electronic structure of Cu and overcomes the higher potential barrier required for the decomposition of water on Cu, which greatly facilitates the hydrolysis process and provides a higher H‐coverage rate for the hydrogenation of NO 3 − , realizing a dynamic equilibrium between the production and consumption of active hydrogen. This component design strategy centered on the amorphous structure opens up a new pathway for the electrochemical NO 3 RR.