Nanostructured Pt-doped 2D MoSe2: an efficient bifunctional electrocatalyst for both hydrogen evolution and oxygen reduction reactions

Abstract

Two-dimensional transition metal dichalcogenides (TMDs) are a new family of 2D materials with features that make them appealing for potential applications in nanomaterials science and engineering. Recently, these 2D TMDs have attracted significant research interest because of the abundant choice of materials with diverse and tunable electronic, optical, chemical, and electrocatalytic properties. Although, the edges of the 2D TMDs show excellent electrocatalytic performance, their basal plane (001) is inert, which hinders their industrial applications for electrocatalysis. Transition metal/chalcogen atom vacancies or doping with some other foreign atoms may be a remedy to activate the inert basal plane. Here, we have computationally designed 2D monolayer MoSe₂ and studied its electronic properties with electrocatalytic activities. A Pt-atom has been doped in the pristine 2D MoSe₂ (i.e., Pt-MoSe₂) to activate the inert basal plane resulting in a zero band gap. This study reveals that the Pt-MoSe₂ is an excellent bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) with the aid of first priciples-based hybrid density functional theory (DFT). The periodic hybrid DFT method has been applied to compute the electronic properties of both the pristine MoSe₂ and Pt-MoSe₂. To determine both the HER and ORR mechanisms on the surface of the Pt-MoSe₂ material, non-periodic DFT calculation has been performed by considering a molecular Pt₁-Mo₉Se₂₁ cluster model. The present study shows that the 2D Pt-MoSe₂ follows the Volmer–Heyrovsky mechanism for the HER with energy barriers of about 9.29 kcal mol⁻¹ and 10.55 kcal mol⁻¹ during the H˙-migration and Heyrovsky reactions. The ORR is achieved by a four-electron transfer mechanism with the formation of two transition energy barriers of about 14.94 kcal mol⁻¹ and 11.10 kcal mol⁻¹, respectively. The lower energy barriers and high turnover frequency during the reactions expose that the Pt-MoSe₂ can be adopted as an efficient bifunctional electrocatalyst for both the HER and ORR. The present studies demonstrate that the exceptional HER and ORR activity and stability performance shown by the MoSe₂ electrocatalyst can be enhanced by Pt-doping, opening a promising concept for the sensible design of high-performance catalysts for H₂ production and O₂ reduction.