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

Abstract Ammonia (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‐NO_x⁻ and electrochemical NO_x⁻ reduction reaction (eNO_xRR) with a bifunctional catalyst, is successfully established. Especially, the bifunctional catalyst of CuCo₂O₄/Ni can simultaneously promote plasma‐air‐to‐NO_x⁻ and eNO_xRR processes. The easy adsorption and activation of O₂ by CuCo₂O₄/Ni greatly improve the NO_x⁻ 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 eNO_xRR. Finally, the “green” NH₃ production achieves excellent FE_NH3 (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.