The Ammonia Adsorption and Desorption Behavior of Nafion

The electrochemical nitrogen reduction reaction (eNRR) for electrochemical ammonia (NH₃) synthesis is considered a promising alternative to the energy-intensive and highly CO₂-emitting Haber-Bosch process. In numerous experiments, the Nafion membrane has been used as an electrolyte or separator. However, Nafion adsorbs and desorbs NH₃, leading to erroneous measurements and making reproducibility extremely difficult. This study systematically investigates the interaction between NH₃ and Nafion, underscoring the strength of the interaction between ammonium-ions (NH₄⁺) and protons (H⁺). We found that minute quantities of synthesized NH₃ are prone to persist within the membrane, albeit without affecting the ion conductivity and resistivity of Nafion. Consequently, the removal of NH₃ from the membrane can occur under conditions where synthesis is not viable. The objective of this work is to heighten awareness regarding the interaction between NH₃ and Nafion and contribute to the attainment of reliable and reproducible outcomes in eNRRs.