New theoretical insights into doping-induced enhancement of ORR activity in molybdenum disulfide: d-p hybridization or the Jahn-Teller effect?

Abstract

Molybdenum disulfide (MoS₂) has emerged as a promising electrocatalyst, garnering considerable attention in recent years. However, the extensive basal-plane sites remain intrinsically inert, thereby limiting the overall catalytic efficiency. Heteroatom doping has been demonstrated as an effective strategy for activating these otherwise inert sites; nevertheless, theoretical investigations remain relatively limited, and the broad diversity of dopants has led to conflicting interpretations of the underlying mechanisms. To elucidate the role of dopants in activating these sites, a total of 64 MoS₂-based electrocatalysts incorporating 3d, 4d, and 5d transition metals, along with selected nonmetals, have been systematically investigated. The results reveal two distinct enhancement pathways: (i) d-p hybridization (d¹-d³ dopants), which elevates the sulfur p-band center and reduces the oxygen reduction reaction (ORR) overpotential to 0.87 V; and (ii) the Jahn-Teller effect (d⁷-d⁹ dopants), which lifts the orbital degeneracy between d _<i>xz</i> /d _<i>yz</i> and d _{<i>x</i> ²-<i>y</i> ²} /d _<i>xy</i> , thereby inducing lattice distortion. The electron rearrangement at the metal center reduces charge transfer, thereby lowering the electron occupancy of the sulfur atom, upshifting its p-band center, and enhancing ORR performance by decreasing the overpotential to 0.53 V. In summary, these findings provide new theoretical insights into substitutional doping and establish guiding principles for the rational design of efficient MoS₂-based ORR electrocatalysts.