Exfoliated 2D Transition Metal Disulfides for Enhanced Electrocatalysis of Oxygen Evolution Reaction in Acidic Medium

The scarcity of inexpensive and efficient electrocatalyst for acid water oxidation to molecular oxygen presents the development of nonprecious catalysts for water oxidation a scientific priority. For water splitting, transition-metal dichalcogenides have attracted great interest as advanced catalysts for hydrogen evolution reaction, but there has been no sincere attention to generate significant anodic current density of oxygen evolution reaction (OER) with these materials. Addressing this unmet need, here, the outstanding catalytic performance of MoS₂ and TaS₂ in OER is demonstrated. Chemically exfoliated 2D thin sheets of MoS₂ and TaS₂, in both of their 1T and 2H polymorph, have been employed for OER catalysis in acid medium. The best performance for oxygen evolution, which is also comparable to benchmark IrO₂, comes out from 1T-MoS₂ followed by 1T-TaS₂, 2H-MoS₂, and 2H-TaS₂. Theoretical study reveals that the dominant catalytic activity is on edge sites instead of surface and corroborates the experimental results of polymorphic dependence of electrocatalytic activity. The materials have also shown moderate durability in the harsh acidic medium. The study brings up new set of electrocatalyst for oxygen evolution in acid regime that hitherto has remained largely unrevealed.