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

Yield validation of dinitrogen reduction reaction (NRR) catalysts with N isotope labeling experiments is frustrated by the high cost of N and the frequent occurrence of NH and NO impurities in commercial N sources. Also, gas diffusion electrode (GDE) cell architectures are relevant to scaling NRR but underexplored and limited by ex situ product analysis methods. To overcome these obstacles, we develop and demonstrate a protocol for NRR 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 NH with ultrahigh mass resolution. The N-containing impurities are also monitored, allowing their influence to be mitigated. A minimum detectable yield of 6 pmol·cm·s (at 2.00 sccm and utilizing a 5 cm electrode) for real-time NH yield rate measurements is achieved while using a cost-effective amount of N (<100 mL).