An exfoliated iron phosphorus trisulfide nanosheet with rich sulfur vacancy for efficient dinitrogen fixation and Zn-N₂ battery

Abstract

Two-dimensional (2D) transition metal compounds have been explored as promising catalysts in dinitrogen electroreduction (NRR) for ammonia synthesis, while the immense basal planes of the 2D materials are inert towards the electrocatalysis. Herein, we report a porous exfoliated FePS₃ nanosheet with rich sulfur vacancy (Vs-FePS₃ NSs) synthesized by electrochemical exfoliation and hydrogenation treatment. Owing to the rich sulfur vacancy and unique 2D morphology with a thickness of ~15 nm and lateral dimension of ~500 nm, Vs-FePS₃ NSs show an excellent activity in electrochemical NRR with a high Faradaic efficiency of 12.36% at − 0.20 V and an ammonia yield rate of 3.88 μg h⁻¹ cm⁻² at − 0.25 V versus reversible hydrogen electrode in acid. Experimental observations reveal the Fe species as real active sites and S vacancies for hydrogenation of N₂ toward a synergistic effect for enhanced NRR. In addition, Vs-FePS₃ NSs can serve as the cathode of a Zn-N₂ battery to achieve a power density of 2.6 mW cm⁻².