First-principles study of noble metal atom doped Fe(100) as electrocatalysts for nitrogen reduction reaction

Abstract

NH3 is one of the most important chemicals on earth and can be used as a chemical feedstock, agricultural fertilizer and hydrogen-rich carrier. Recently, the technology of NH3 synthesis by electrochemical nitrogen reduction reaction (NRR) has attracted extensive attention. The core problem of the NRR is the development of electrocatalysts with high activity, selectivity and stability. Fe is not only a constituent element of biological nitrogenase, but also a widely used catalyst material in industrial NH3 synthesis. Due to the presence of unoccupied orbitals, it shows some potential in the process of N2 adsorption and desorption. Therefore, the catalytic activity of Fe(100) for the NRR was studied based on density functional theory, and the electronic properties of Fe(100) were regulated by doping noble metal (NM= Ru, Rh, Pd, Os, Ir, Pt) atoms to reduce the energy barrier and enhance the activity and selectivity of the catalyst. Through the screening of three important processes including N2 adsorption and activation, N2H formation and NH3 desorption, the catalytic activity of Ir atom doped Fe(100) (Ir@Fe(100)) was the highest, and the energy barrier of first hydrogenation step was 0.342 eV. More importantly, Ir@Fe(100) can significantly inhibit the hydrogen evolution reaction. This study can provide some theoretical reference and guidance for the design and preparation of Fe-based catalysts.