Strong Acid-Mediated Proton Transfer via Water Tunneling Fosters Hydrogen Evolution Reaction on MoS<sub>2</sub> Derivatives under Alkaline Conditions
Matteo Pugliesi, Giulia Alice Volpato, Ida Ritacco, Giulia Tuci, Mattia Cattelan, Andrea Rossin, Yuefeng Liu, Lucia Caporaso, Matteo Farnesi Camellone, Giuseppe Santoriello, Elena Colusso, Stefano Agnoli, Giuliano Giambastiani
Abstract
High Resolution Image Download MS PowerPoint Slide The surface functionalization of chemically exfoliated MoS 2 ( CE -MoS 2 ) nanoflakes with Brønsted-acid end-capped aryl fragments adds an additional level of complexity to the comprehension of the correlation between the electron-donating strength of covalently grafted organic groups (Hammett parameter) and the HER performance of these hybrids. MoS 2 nanoflakes decorated with aryl-sulfonic acids promote proton transfer via tunneling of H-species, where weaker benzoic acid groups fail. Thus, surface-engineered CE -MoS 2 bearing sulfonic-acid end-capped dangling arms acts as an electrocatalyst that boosts HER kinetics even under an alkaline environment, where water dissociation represents the bottleneck of the process. Density functional theory (DFT) calculations have been used to corroborate experimental evidence and speculate on the role of acidic moieties with respect to water molecule tunneling and dissociation at the surface of the functionalized chalcogenide. The study represents a significant advance in the development of pH-insensitive electrocatalysts for HER.