Enhanced electrochemical reduction of N2 to NH3 by interfacial engineering of biomass-derived Fe, Mo-bimetallic composite

Abstract

Electrocatalytic nitrogen reduction reaction (NRR) for the synthesis of ammonia (NH3) is one of the green and mild methods of artificial nitrogen fixation, promising as an alternative to replace the existing industrial process. Under the requirements of green chemistry and sustainable development, the design and development of highly active and stable electrocatalysts is very important for improved synthesis performance. Mimicking from the natural nitrogenase, Fe and Mo based catalysts have attracted much attention due to their superior catalytic performance for N2 adsorption and activation. In this work, an interfacial engineering strategy has been used to prepare a Fe, Mo-bimetallic electrocatalyst for the electrosynthesis of NH3. In detail, the pre-pyrolyzed biochar-based Fe2O3 composites were decorated with nano-flowered MoS2/MoO2 hybrids by a solvothermal process (MoS2/MoO2@Fe2O3/BC). As confirmed by the extensive characterization, the further modification not only introduced functional counterparts into the electrocatalysts but also regulated the morphology of the nanostructure. The electrochemical tests showed that the highest NH3 yield rate of MoS2/MoO2@Fe2O3/BC was 4.87 μg h− 1 cm−2 and highest FE was 16.5% in 0.1 M Na2SO4. The catalytic stability and durability were also presented in the longtime electrolysis and cycling experiments. The improved catalytic performance of decorated catalyst, as evidenced by the comparison with Fe2O3/BC, is attributed to the increased electrocatalytic active area, the moderated hydrophilicity, and the synergistic effect of Fe, Mo-bimetallic active sites. This study provides a new perspective for the design and development of low-cost transition metal complexes as electrocatalysts for nitrogen reduction reactions.