Nitrogen Reduction Testing with Real-Time ¹⁵NH₃ Yield Quantification Using Orbital Multiturn Time-of-Flight Mass Spectrometry

High Resolution Image Download MS PowerPoint Slide Yield validation of dinitrogen reduction reaction (N 2 RR) catalysts with 15 N isotope labeling experiments is frustrated by the high cost of 15 N 2 and the frequent occurrence of 15 NH 3 and 15 NO x impurities in commercial 15 N 2 sources. Also, gas diffusion electrode (GDE) cell architectures are relevant to scaling N 2 RR but underexplored and limited by ex situ product analysis methods. To overcome these obstacles, we develop and demonstrate a protocol for N 2 RR catalyst testing using a scalable GDE cell architecture and specialized test station that facilitates in-line product analysis with multiturn time-of-flight mass spectrometry. This approach provides robust yield measurements through real-time monitoring of 15 NH 3 with ultrahigh mass resolution. The 15 N-containing impurities are also monitored, allowing their influence to be mitigated. A minimum detectable yield of 6 pmol·cm –2 ·s –1 (at 2.00 sccm and utilizing a 5 cm 2 electrode) for real-time 15 NH 3 yield rate measurements is achieved while using a cost-effective amount of 15 N 2 (<100 mL).