Interface Engineering of the Cu_1.5Mn_1.5O₄/CeO₂ Heterostructure for Highly Efficient Electrocatalytic Nitrate Reduction to Ammonia.

Abstract

The electrochemical nitrate reduction reaction (NO₃RR) is considered a sustainable technology to convert the nitrate pollutants to ammonia. However, developing highly efficient electrocatalysts is necessary and challenging given the slow kinetics of the NO₃RR with an eight-electron transfer process. Here, a Cu_1.5Mn_1.5O₄ (CMO)/CeO₂ heterostructure with rich interfaces is designed and fabricated through an electrospinning and postprocessing technique. Benefiting from the strong coupling between CMO and CeO₂, the optimized CMO/CeO₂-2 catalyst presents excellent NO₃RR performance, with NH₃ Faraday efficiency (FE) up to 93.07 ± 1.45% at -0.481 V vs reversible hydrogen electrode (RHE) and NH₃ yield rate up to 48.06 ± 1.32 mg cm^-2 h^-1 at -0.681 V vs RHE. Theoretical calculations demonstrate that the integration of CeO₂ with CMO modulates the adsorption/desorption process of the reactants and intermediates, showing a reduced energy barrier in the rate determination step of NO* to N* and achieving an outstanding NO₃RR performance.