Preparation of Nafion Membranes for Reproducible Ammonia Quantification in Nitrogen Reduction Reaction Experiments

Abstract

This study highlights the importance of following a strict protocol for Nafion membrane pretreatment for electrochemical nitrogen reduction reaction experiments. Atmospheric ammonia pollution can be introduced to the experimental setup through membranes and interpreted falsely as catalysis product from N2. The sources of ammonia contamination vary drastically between locations worldwide and even within the same location between days depending on temperature, wind direction, fertilizer use, and manure accumulation in its vicinity. The study shows that significant amounts of ammonium is accumulated in the membranes after commonly practiced pretreatment methods, where the amount depends on the ammonia concentration in the surrounding of the experiment. Therefore, we introduce a new pretreatment method which removes all the ammonium in the membrane. The membranes can be stored for several days but a short final step in the method needs to be carried out right before NRR experiments.

Splicing the active phases of copper/cobalt-based catalysts achieves high-rate tandem electroreduction of nitrate to ammonia

“…The electrochemical tests were performed using a three-electrode system connected to the Gamry workstation in a typical H-type cell. The H-type cell was separated by a Nafion 117 membrane (Dupont) that was pretreated following reported procedures 82 . The catalysts were used as the working electrode, while Ag/AgCl (3 M KCl) and platinum mesh were used as the reference and counter electrodes, respectively.…”

Demonstration of no catalytical activity of Fe‐N‐C and Nb‐N‐C electrocatalysts toward nitrogen reduction using in‐line quantification

“…The compartments of the working and counter electrodes (WE and CE) were separated by a Nafion™ 211 membrane. The Nafion™ was pretreated to prevent contamination of ammonia from the atmosphere as previously described 31 . Both electrode chambers were filled with 25 ml of 0.1 M KOH.…”

“…The method only requires 200 μl volume of sample and has a detection limit as low as 1 ppb for ammonia, which allows for thorough and high-throughput screening of potential NRR electrocatalysts. 31 Single atom catalysts (SACs) are a family of nanoengineered materials that contain atomically dispersed active sites embedded in a conducting framework, such as MoS 2 , graphene, diyene, and nitrogen-doped carbon. 32 SACs are attractive electrocatalytic materials due to low cost, diverse strategies of preparation and fabrication, and unique catalytic activity.…”

“…This minimizes external sources of contamination in samples providing a reproducible and reliable method to study NRR. The method only requires 200 μl volume of sample and has a detection limit as low as 1 ppb for ammonia, which allows for thorough and high‐throughput screening of potential NRR electrocatalysts 31 …”

Strategies in cell design and operation for the electrosynthesis of ammonia: status and prospects

“…Experimental studies have also provided evidence that improved cell components and/or interfacial designs can have significant contributions to elevating the ENRR performance under suitable operating conditions. [35][36][37][38][39][40] To rectify false positives, contaminationprone cell components (e.g., electrolyte and separator) are being recognized, 29,41 and contamination-free alternatives are proposed with the parallel execution of rigorous cell operation protocols. 26,27,42 Therefore, designing a reliable electrolytic cell and operating it at beneficial conditions with rigorous protocols holds promise in improving the unsatisfactory development in the field of NH 3 electrosynthesis.…”