Dynamic Stabilization of Cu<sup>δ+</sup> in Heterostructured Ag<sup>0</sup>‐CuAgO<sub>x</sub> for High‐Performing Nitrate Electroreduction
Hong Huang, Yechuan Zhang, Wenjiang Chen, Jinli Chen, Xuhui Zou, Jingjing Lv, Xueqiu Chen, Zhangfeng Shen, Zhigang Ge, Longhua Guo, Yonggang Yao, Yangang Wang
Abstract
Abstract Oxide‐derived copper (OD‐Cu) has exhibited significant promise in nitrate electroreduction reaction (NO 3 RR) due to their hybrid Cu oxide states (Cu δ+ ) for stabilizing key reaction intermediates. However, owing to the intrinsic vulnerability of Cu δ+ reduction during NO 3 RR, it is still challenging to develop highly active and durable OD‐Cu catalysts. Herein, a unique strategy is reported to stabilize the Cu + state by dynamically introducing metallic Ag clusters in the oxidized CuAgO x nanosheets to form heterostructure Ag 0 ‐CuAgO x . Operando X‐ray absorption spectroscopy and diffuse reflection infrared Fourier transform spectroscopy reveal a strong correlation between NH 3 production and Cu δ+ content in Ag 0 ‐CuAgO x , with peak performance achieved when Cu + is maximized. Ag 0 acts as an electron acceptor, preventing the over‐reduction of Cu δ+ during NO 3 RR. The stabilized Cu + in Ag 0 ‐CuAgO x helps achieve outstanding long‐term stability of 400 h for NH 3 production, surpassing most of the state‐of‐the‐art Cu‐based electrocatalysts. Computational studies and ultraviolet photoelectron spectrometer confirm that Ag 0 functions as the electronic buffer and enables electron transfer from Cu 2 O to Ag to generate electron‐deficient Cu sites, thus turning the Cu d‐band center with favorable adsorption energies for key intermediates to facilitate NH 3 formation. The study paves the way to develop valence‐stabilized catalysts for a range of electroreduction reactions.