Engineering the Electronic Structure of MoS₂ Nanorods by N and Mn Dopants for Ultra-Efficient Hydrogen Production

Abstract

Developing economical and efficient electrocatalysts with nonprecious metals for the hydrogen evolution reaction (HER), especially in water-alkaline electrolyzers, is pivotal for large-scale hydrogen production. Recently, both density functional theory (DFT) calculations and experimental studies have demonstrated that earth-abundant MoS2 is a promising HER electrocatalyst in acidic solution. However, the HER kinetics of MoS2 in alkaline solution still suffer from a high overpotential (90–220 mV at a current density of 10 mA cm–2). Herein, we report a combined experimental and first-principle approach toward achieving an economical and ultraefficient MoS2-based electrocatalyst for the HER by fine-tuning the electronic structure of MoS2 nanorods with N and Mn dopants. The developed N,Mn codoped MoS2 catalyst exhibits an outstanding HER performance with overpotentials of 66 and 70 mV at 10 mA cm–2 in alkaline and phosphate-buffered saline media, respectively, and corresponding Tafel slopes of 50 and 65 mV dec–1. Moreover, the catalyst also exhibits long-term stability in HER tests. DFT calculations suggest that (1) the electrocatalytic performance can be attributed to the enhanced conductivity and optimized electronic structures for facilitating H* adsorption and desorption after N and Mn codoping and (2) N and Mn dopants can greatly activate the catalytic HER activity of the S-edge for MoS2. The discovery of a simple approach toward the synthesis of highly active and low-cost MoS2-based electrocatalysts in both alkaline and neutral electrolytes allows the premise of scalable production of hydrogen fuels.