Integrated dual-GDE system for high-efficiency ammonia synthesis from dilute no and energy-saving direct gaseous recovery

Title : Integrated dual-GDE system for high-efficiency ammonia synthesis from dilute no and energy-saving direct gaseous recovery

Abstract:

Electrochemical upcycling of nitrogenous air pollutants into green energy carriers offers a sustainable alternative to the energy-intensive Haber-Bosch process. However, conventional aqueous-phase nitric oxide reduction reaction (NORR) is strictly limited by low NO solubility and the complex post-separation of aqueous ammonium ions NH₄⁺. Here, we present an integrated, highly energy-efficient dual-gas diffusion electrode (GDE) platform that couples high-rate NORR with continuous gaseous ammonia NH₃ recovery from dilute NO (1–10% in Ar).  In Stage 1, a GDE loaded with carbon-supported nanoscale zero-valent iron (Fe/C) successfully bypasses mass transport limitations, achieving a high NH₃ Faradaic efficiency of 96% at 1% NO feed and a maximum production rate of 1239 umol/cm²h at 10% NO in 0.5M H₂SO₄. Density functional theory (DFT) calculations confirm that Fe/C selectively lowers the energy barrier for N–O bond cleavage in the H₂NO intermediate. In Stage 2, the generated NH₄⁺stream is directly routed into a GDE-based electrochemical stripping (GDE-ES) cell. Taking advantage of a highly alkaline cathodic microenvironment and an air sweep gas (20mL/min) functioning simultaneously as an oxygen reduction reaction (ORR) reactant and stripping carrier, the system achieves a superior nitrogen flux of 770 gN/m²/d at 10mA cm². Benefit from cathodic ORR voltage compensation, the net energy demand was constrained to 9.44 kWh/ kg N, representing a 43–66% energy saving compared to conventional air stripping. This work establishes a closed-loop electrochemical route for converting industrial off-gases into high-purity chemical resources

Biography:

Dr. DongYeon Kim is a Senior Researcher at Blueone Research Institute, Daejeon, Republic of Korea. His research focuses on electrocatalytic reaction engineering, development of gas diffusion electrodes (GDE), and electrochemical resource recovery from industrial pollutants, particularly concentrating on nitrogen-cycle transformations and sustainable energy technologies.