Promoted Two‐Step Ammonia Synthesis with CoOOH/Co foam at Ampere‐Level Current Density and Nearly 100% Faraday Efficiency from Air and Water

Abstract Ammonia (NH₃) is regarded as an essential hydrogen storage material in the new energy field, and plasma‐electrocatalytic synthesis of NH₃ (PESA) is an alternative to the traditional Haber–Bosch process. Here, a bifunctional catalyst CoOOH/CF is proposed to enhance the PESA process. Benefiting from the efficient activation of O₂ by CoOOH/CF, NO_x⁻ yield rate can reach the highest value of 171.90 mmol h⁻¹ to date. Additionally, CoOOH holds a more negative d‐band center, thereby exhibiting weaker adsorption toward NO^*, lowering the energy barrier for the rate determining step, resulting in a high NH₃ yield rate (302.55 mg h⁻¹ cm⁻² at −0.8 V) with ampere‐level NH₃ current density (2.86 A cm⁻² at −0.8 V) and nearly 100% Faraday efficiency (FE, 99.8% at −0.6 V). Moreover, CoOOH/CF achieves an excellent 4.54 g h⁻¹ NH₃ yield rate with 97.9% FE in an enlarged electrolyzer, demonstrating the feasibility of PESA on a large scale.