A Cascade Jet Plasma Oxidation─electroreduction System Using Pd‐Ni Dual‐Site Catalyst for Sustainable Ammonia Production from Air

Abstract Electrocatalytic N₂ reduction reaction (eNRR) has been deemed as an alternative approach to the Haber‐Bosch (H‐B) process for ammonia (NH₃) production, but it remains a huge challenge. Here jet plasma oxidation of N₂ is reported in air into NO_x and subsequently NO₂⁻ coupling with electrochemical NO₂⁻ reduction reaction (pN₂─eNO₂⁻RR) over PdNi alloying nanoparticles on N‐doped carbon nanotubes (PdNi/N‐CNTs) for NH₃ synthesis. The results demonstrate that the jet plasma reactor possesses excellent gas reforming capacity to achieve the largest NO₂⁻ yield rate of 30.46 mmol h⁻¹ with a low energy consumption of 2.66 kWh mol_N⁻¹. For subsequent eNO₂⁻RR, PdNi/N‐CNTs can afford an NH₃ yield of 34.96 mg h⁻¹ mg_cat.⁻¹ and a faradaic efficiency (FE) of 98.21% at −0.38 and 0.02 V (vs RHE), respectively. In situ spectroscopic characterizations combined with theoretical calculations unveil that PdNi/N‐CNTs provide Pd and Ni dual active sites, enabling NO₂⁻ activation on the Ni site and active H^* provision on the Pd site to facilitate eNO₂⁻RR. A cascade pN₂‐eNO₂⁻RR system is constructed for sustainable NH₃ production, achieving a stable NH₃ yield rate of 25.56 mmol h⁻¹, an average FE >85%, as well as NO_x to NH₃ conversion efficiency of 44.62% at constant ampere‐level current with finally collection of gram‐level (NH₄) ₂SO₄ product.