Ni‐ and Co‐Substituted Metallic MoS<sub>2</sub> for the Alkaline Hydrogen Evolution Reaction
Nuwan H. Attanayake, Lakshay Dheer, Akila C. Thenuwara, Sasitha C. Abeyweera, Coby Collins, Umesh V. Waghmare, Daniel R. Strongin
Abstract
Abstract A metallic MoS 2 (M−MoS 2 ) catalyst containing either Ni or Co with excellent activity for the hydrogen evolution reaction (HER) under alkaline electrocatalytic conditions was investigated. To synthesize the 3d transition metal containing electrocatalysts, 1–20 at.% Ni or Co was substituted into the lattice of orthorhombic MoO 3 and the doped metal oxide precursor was sulfided and converted to Ni/M−MoS 2 or Co/M−MoS 2 . Raman spectroscopy and photoelectron spectroscopy were used to verify that the Ni or Co substituted MoS 2 was the metallic‐like 1T′ phase of the metal dichalcogenide. The 10 at.% Ni/M−MoS 2 (10 at.% Co/M−MoS 2 ) electrochemical HER catalyst investigated under alkaline conditions exhibited a low onset potential of ∼−75 mV (∼−100 mV) and overpotential of −145 mV (−160 mV) at a current density of 10 mA/cm 2 . Pristine M−MoS 2 exhibited both a higher onset potential of ∼−150 mV and a higher overpotential of −240 mV at 10 mA/cm 2 . First‐principles density functional theory analysis showed that substitution of 3d transition metals like Ni and Co in the metallic MoS 2 structure notably stabilized the distorted polytype of 1T′−MoS 2 , lowering the free energy for H binding and H 2 O dissociation, both important steps in alkaline HER, giving rise to enhanced activity towards HER.