Edge-hosted CoFeB active sites with graphene nanosheets for highly selective nitrogen reduction reaction towards ambient ammonia synthesis

Abstract

Electrocatalytic nitrogen reduction reaction (NRR) offers a suitable alternative to the conventional high energy intensive Haber–Bosch process for ambient ammonia (NH3) production without the release of greenhouse gases. Herein, a chemical reduction method is employed to effectively fabricate a hierarchical 3D nanostructure composed of CoFeB nanospheres precisely enveloped and interconnected with dynamically adaptable reduced graphene oxide (rGO) nanosheets for electrocatalytic NRR. Interconnected 3D CoFeB@ rGO nanostructures selectively reduced gaseous N2 to NH3 and demonstrated high Faradaic efficiency (31.6%) and NH3 yield rate (35 μg h−1 mg−1) at − 0.2 V in 0.05 M H2SO4, comparable to various state-of-the-art electrocatalytic materials for ambient NRR. Density functional theory (DFT) simulations additionally verify that interconnected CoFeB nanospheres with mechanically flexible graphene nanosheets are beneficial in lowering the energy threshold for N2 adsorption and successive protonation. First example of CoFeB@rGO heterostructures as electrocatalysts for high efficiency, pH-universal NRR to NH3 synthesis is highlighted in this study.