Revised Nitrogen Reduction Scaling Relations from Potential-Dependent Modeling of Chemical and Electrochemical Steps

22 May 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The electrochemical nitrogen reduction reaction (NRR) is a promising route to enable carbon-free ammonia production. However, it is limited by the poor activity and selectivity of current catalysts. The rational design of superior NRR electrocatalysts requires a detailed mechanistic understanding of current material limitations to inform how these can be overcome. The current understanding of how scaling limits NRR on metal catalysts is predicated on a simplified reaction pathway that only considers proton-coupled electron transfer (PCET) steps. Here, we apply grand canonical density functional theory to investigate a more comprehensive NRR mechanism that includes both electrochemical and chemical steps on 23 metal surfaces in solvent under an applied potential. We applied Φmax, a grand canonical adaptation of the Gmax descriptor, to evaluate trends in catalyst activity. This approach produces a Φmax “volcano” diagram for NRR activity scaling on metals that qualitatively differs from the scaling relations identified when only PCET steps are considered. NH3* desorption was found to limit NRR activity for materials at the top of the volcano and truncates the volcano’s peak at increasingly reducing potentials. These revised scaling relations may inform the rational design of superior NRR electrocatalysts. This approach is transferable to study additional materials and reaction chemistries where both electrochemical and chemical steps are modeled under an applied potential.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.