Magneto-Electrochemical Ammonia Synthesis: Boosting Nitrite Reduction Activity by the Optimized Magnetic Field Induced Spin Polarized System

Abstract

Using low and optimized magnetic field along with electric field is a novel strategy to facilitate electrochemical nitrite reduction reaction (NO₂RR). Herein, the magnetic field assisted electrocatalytic ammonia synthesis employing spin-thrusted β-MnPc at 95 mT magnetic field is explored. The calculated rate of ammonia generation is 16603.4 µg h⁻¹ mg_cat⁻¹, which is almost twice that of the nonpolarized manganese phthalocyanine (MnPc) catalyst. Additionally, the Faradaic efficiency (FE) at –0.9 V versus RHE is found to be 92.9%, significantly higher compared to the nonpolarized MnPc catalyst. In presence of external magnetic field, MnPc catalysts provide a better electron transfer channel which results in a lower charge transfer resistance and hence better electrochemical performances. Density functional theory (DFT) result further verifies that magnetic field induced β-MnPc has a lower potential barrier (0.51 eV) for the protonation of NO* than nonpolarized β-MnPc (1.08 eV), which confirms the enhanced electrochemical nitrite reduction to ammonia.