Mechanistic analysis of the dissociative reduction of nitrogen to ammonia by ZnMn<inf>2</inf>O<inf>4</inf> catalyst derived from spent batteries

Ammonia (NH3) production via electrochemical nitrogen reduction is gaining popularity as a clean and sustainable alternative to the Haber−Bosch process (HBP). Here we report ZnMn2O4 derived from spent primary Zn-C battery as an efficient electrocatalyst for nitrogen reduction reaction (NRR). This catalysts needs only water apart from N2 as reactant. The catalyst exhibits high activity and selectivity with an NH3 yield rate of 143 ± 3 μg h−1 mgcat−1 and a faradaic efficiency of 49 ± 2 % at − 0.5 V vs. RHE. Mechanistic modeling of the experimental data was carried out to gain insight into the kinetic parameters. DFT calculations were also employed to corroborate the mechanism hypothesized for NRR in this work.