Interfacially Engineered Nanoporous Cu/MnOx Hybrids for Highly Efficient Electrochemical Ammonia Synthesis via Nitrate Reduction

Abstract Electrochemical reduction of nitrate to ammonia (NH 3 ) not only offers a promising strategy for green NH 3 synthesis, but also addresses the environmental issues and balances the perturbed nitrogen cycle. However, current electrocatalytic nitrate reduction processes are still inefficient due to the lack of effective electrocatalysts. Here 3D nanoporous Cu/MnO x hybrids are reported as efficient and durable electrocatalysts for nitrate reduction reaction, achieving the NH 3 yield rates of 5.53 and 29.3 mg h −1 mg cat. −1 with 98.2% and 86.2% Faradic efficiency in 0.1 m Na 2 SO 4 solution with 10 and 100 m m KNO 3 , respectively, which are higher than those obtained for most of the reported catalysts under similar conditions. Both the experimental results and density functional theory calculations reveal that the interface effect between Cu/MnO x interface could reduce the free energy of rate determining step and suppress the hydrogen evolution reaction, leading to the enhanced catalytic activity and selectivity. This work provides an approach to design advanced materials for NH 3 production via electrochemical nitrate reduction.