Tweaking the Intrinsic Properties of MoSe ₂ Using a Doping Strategy for Enhanced Oxygen Evolution Reaction under Alkaline Conditions

Molybdenum selenide (MoSe2) is a layered 2D material that belongs to the class of transition metal dichalcogenides, endowed with catalytic properties, and has been explored for the electrocatalytic oxygen evolution reaction (OER). The limited intrinsic activity and durability of MoSe2 restrict its practical viability. To address this issue, a 3d transition metal doping strategy is employed in the present study, and it is demonstrated that among the Fe-, Cu-, and Co-doped MoSe2 systems, cobalt-doped MoSe2 (Co–MoSe2) exhibits the best OER activity. Intriguingly, the doping strategy alters the morphology and modulates the intrinsic properties of the host MoSe2. For example, Co doping promotes the transition of a sheet-like morphology to a flower-like nanostructure (with exposed active sites and edges). As a result, the density of active sites increased, which improved the electrochemical active surface area (ECSA). Further, Co doping alters the energy levels in MoSe2 and enhances the charge transfer kinetics, as demonstrated using electrochemical impedance spectroscopy analysis. Interestingly, the oxidation state of Mo in MoSe2 is exclusively +4, whereas the introduction of Co2+ into MoSe2 leads to the partial oxidation of Mo into the +6 state, which regulates adsorption energetics of the OER intermediates and favors the OER process. Altogether, these enriched properties of Co–MoSe2 enabled us to achieve 50 mA cm–2 at a low overpotential of 290 mV, accompanied by appreciable durability for the OER process. These findings suggest that Co doping into MoSe2 is a promising approach that facilitates the elaborate modulation of the layered MoSe2 structure and properties for a wide range of applications.