Issue 37, 2023

Patterning edge-like defects and tuning defective areas on the basal plane of ultra-large MoS2 monolayers toward the hydrogen evolution reaction

Abstract

The catalytic sites of MoS2 monolayers towards hydrogen evolution are well known to be vacancies and edge-like defects. However, it is still very challenging to control the position, size, and defective areas on the basal plane of MoS2 monolayers by most of the defect-engineering routes. In this work, the fabrication of etched arrays on ultra-large supported and free-standing MoS2 monolayers using a focused ion beam (FIB) is reported for the first time. By tuning the Ga+ ion dose, it is possible to confine defects near the etched edges or spread them over ultra-large areas on the basal plane. The electrocatalytic activity of the arrays toward the hydrogen evolution reaction (HER) was measured by fabricating microelectrodes using a new method that preserves the catalytic sites. We demonstrate that the overpotential can be decreased up to 290 mV by assessing electrochemical activity only at the basal plane. High-resolution transmission electron microscopy images obtained on FIB patterned freestanding MoS2 monolayers reveal the presence of amorphous regions and X-ray photoelectron spectroscopy indicates sulfur excess in these regions. Density-functional theory calculations enable identification of catalytic defect sites. Our results demonstrate a new rational control of amorphous-crystalline surface boundaries and future insight for defect optimization in MoS2 monolayers.

Graphical abstract: Patterning edge-like defects and tuning defective areas on the basal plane of ultra-large MoS2 monolayers toward the hydrogen evolution reaction

Supplementary files

Article information

Article type
Paper
Submitted
17 Qad 2023
Accepted
02 Way 2023
First published
04 Way 2023

J. Mater. Chem. A, 2023,11, 19890-19899

Patterning edge-like defects and tuning defective areas on the basal plane of ultra-large MoS2 monolayers toward the hydrogen evolution reaction

B. R. Florindo, L. H. Hasimoto, N. de Freitas, G. Candiotto, E. N. Lima, C. de Lourenço, A. B. S. de Araujo, C. Ospina, J. Bettini, E. R. Leite, R. S. Lima, A. Fazzio, R. B. Capaz and M. Santhiago, J. Mater. Chem. A, 2023, 11, 19890 DOI: 10.1039/D3TA04225A

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