Tuning the Electron Localization of Gold Enables the Control of Nitrogen‐to‐Ammonia Fixation

The (photo)electrochemical N 2 reduction reaction (NRR) provides a favorable avenue for the production of NH 3 using renewable energy in mild operating conditions. Understanding and building an efficient catalyst with high NH 3 selectivity represents an area of intense interest for the early stages of development for NRR. Herein, we introduce a CoO x layer to tune the local electronic structure of Au nanoparticles with positive valence sites for boosting conversion of N 2 to NH 3 . The catalysts, possessing high average oxidation states (ca. 40 %), achieve a high NH 3 yield rate of 15.1 μg cm −2  h −1 and a good faradic efficiency of 19 % at −0.5 V versus reversible hydrogen electrode. Experimental results and simulations reveal that the ability to tune the oxidation state of Au enables the control of N 2 adsorption and the concomitant energy barrier of NRR. Altering the Au oxidation state provides a unique strategy for control of NRR in the production of valuable NH 3 .