Electrochemical macrokinetics analysis of nitrite electrocatalytic reduction to ammonia

Electrocatalytic nitrite reduction (e-NO₂⁻RR) offers an attractive strategy for industrial green ammonia synthesis. The understanding of electrochemical kinetics is the core to guarantee the efficient operation of e-NO₂⁻RR system. However, the application of the widely used Butler–Volmer equation should be restricted to the constraint of non-mass transfer effects. In this work, an electrochemical macrokinetics equation for mass transfer restriction region was developed based on the traditional macrokinetics thought, which combined the Practical Butler–Volmer equation and Nernst-Plank equation. The model validation was carried out by the combination of multiphysics-field simulation, computational fluid dynamics simulation and experiments, and the results show that the average relative error between experiments and simulations is less than 2%. The results in this article contribute to an in-depth understanding of the kinetics behavior for e-NO₂⁻RR and achieve the extension of electrochemical kinetics equation from non-mass transfer restriction region to mass transfer restriction region.