Configurational Entropy and Compositional Effects in Fe‐Based Oxide 2D Sheets for Nitrate Electroreduction
Muhammad Usman, Zhehao Sun, Yi‐Lun Chen, Kaili Liu, Xuechen Jing, Soshan Cheong, Zeno R. Ramadhan, Jiayi Chen, Shuwen Cheng, Ary Anggara Wibowo, Daniel Macdonald, Lucy Gloag, Nicholas Cox, Richard D. Tilley, Zongyou YinABSTRACT
Entropy engineering offers a promising strategy for constructing multicomponent electrocatalysts, yet its role in nitrate‐to‐ammonia electroreduction remains insufficiently understood. Herein, we design a series of Fe‐based oxide two‐dimensional sheets with low‐, medium‐, and high‐entropy compositions by incorporating Cu, Co, Mn, and Zn into Fe 3 O 4 frameworks. This compositional series enables a comparative evaluation of how elemental combination, oxidation‐state distribution, local electronic environment, and electrochemically accessible interfaces influence nitrate reduction reaction (NO 3 RR) performance. The FeCuCoMnZnO x catalyst delivers an ammonia yield rate of 10.9 mgh −1 mg cat −1 and a Faradaic efficiency of 94% at −0.55 V vs. reversible hydrogen electrode. Integrated experimental and theoretical analyses suggest that the catalytic behaviour is associated with the combined effects of composition‐dependent electronic structure, mixed‐valence metal centres, and heteroatomic bridge‐site configurations. These features are associated with a calculated d‐band centre in a favourable range for balancing NO 3 RR intermediate adsorption and desorption, while selected heteroatomic configurations lower key reaction barriers compared with the corresponding homoatomic sites. Post‐cyclic‐stability characterization further indicates partial surface reduction and oxidation‐state redistribution under NO 3 RR operating conditions. In situ Fourier‐transform infrared and Raman spectroscopy provide potential‐dependent evidence for NO 3 RR‐related surface intermediates on FeCuCoMnZnO x .