A Bifunctional Catalyst for Green Ammonia Synthesis from Ubiquitous Air and Water

Abstract

AbstractAmmonia (NH3) is essential for modern agriculture and industry, and, due to its high hydrogen density and no carbon emission, it is also expected to be the next‐generation of “clean” energy carrier. Herein, directly from air and water, a plasma‐electrocatalytic reaction system for NH3 production, which combines two steps of plasma‐air‐to‐NOx− and electrochemical NOx− reduction reaction (eNOxRR) with a bifunctional catalyst, is successfully established. Especially, the bifunctional catalyst of CuCo2O4/Ni can simultaneously promote plasma‐air‐to‐NOx− and eNOxRR processes. The easy adsorption and activation of O2 by CuCo2O4/Ni greatly improve the NOx− production rate at the first step. Further, CuCo2O4/Ni can also resolve the overbonding of the key intermediate of *NO, and thus reduce the energy barrier of the second step of eNOxRR. Finally, the “green” NH3 production achieves excellent FENH3 (96.8%) and record‐high NH3 yield rate of 145.8 mg h−1 cm−2 with large partial current density (1384.7 mA cm−2). Moreover, an enlarged self‐made H‐type electrolyzer improves the NH3 yield to 3.6 g h−1, and the obtained NH3 is then rapidly converted to a solid of magnesium ammonium phosphate hexahydrate, which favors the easy storage and transportation of NH3.