High-Density Defects Activating Fe-Doped Molybdenum Sulfide@N-Doped Carbon Heterostructures for Efficient Electrochemical Hydrogen Evolution

Abstract

Vacancy defects caused by doping are beneficial to optimizing the regional electronic structure and increasing exposed active sites, and it is vital to improve the efficiency of hydrogen evolution reaction (HER). Herein, we constructed the Fe-doped molybdenum sulfide encapsulated with N-doped carbon (FeMoSN@NC), which with ultrathin edge-curled layer structure. Fe-doping realized with Prussian blue nanocages as the precursors, which plays a crucial role in the formation of ultrathin layer assembled microspheres. Experimental tests and theoretical calculations show that the Fe-doping can not only expand the interlayer of MoS2 (∼11 Å) to obtain ultrathin layers but also embed into the in-plane location of MoS2 to form high-density doping and vacancy defects. The regulation of regional active sites caused by Fe-doping can enhance the intrinsic catalytic activity of catalyst, including more active sites for HER, appropriate Gibbs free energy of hydrogen adsorption (−0.11 eV of Fe1Mo-VMo,S), and low resistance for carrier transfer (9 Ω). FeMoSN@NC as the HER electrocatalyst exhibits efficient activity with a Tafel slope of 67 mV dec–1 and an overpotential of 150 mV at the current density of −100 mA mg–1. The above insights provide new transition metal doping strategy for efficient molybdenum sulfide electrocatalysts with optimized active sites and increased electrochemical active area.