The role of transition metal dopants in TMDs for optimal hydrogen evolution reactions

초록

Transition metal dichalcogenides (TMDs) doped with additional transition metals offer great potential as catalysts for water splitting. Introducing different transition metals into TMDs is a particularly effective method for enhancing the hydrogen evolution reaction (HER), as it can optimize the process of hydrogen adsorption and production. We have thoroughly investigated the patterns in the changes in hydrogen adsorption free energy (ΔG_H?), a key indicator of HER efficiency, for various TMDs doped with different transition metals. We analyzed 150 distinct doped TMDs at the atomic level to understand the underlying causes of the changes in ΔG_H? when different transition metals are introduced. We identified two primary factors influencing hydrogen adsorption on doped TMDs: (1) alterations in the charge of chalcogen atoms in TMDs doped with early transition metals, where hydrogen atoms bond, and (2) the energy required to deform the structure of TMDs doped with late transition metals to accommodate the added atoms. Furthermore, we offer a novel explanation for how vacancies in transition metal-doped TMDs can improve the hydrogen adsorption free energy and, consequently, the HER performance. We propose that adjusting electrostatic properties in early transition metal-doped TMDs and structural characteristics in late transition metal-doped TMDs can effectively achieve a neutral hydrogen adsorption free energy, leading to the development of TMD catalysts with exceptional water splitting performance.