Strain engineering of two-dimensional piezo-photocatalytic materials for hydrogen production

TL;DR

This study uses first-principles DFT simulations to show that applying electric bias and tensile biaxial strain to TMDC monolayers enhances their photocatalytic efficiency for hydrogen production by optimizing electronic properties and hydrogen adsorption.

Contribution

It introduces a method to improve TMDC photocatalysts for hydrogen evolution by combining electric bias and strain engineering, which was not previously explored.

Findings

Electric bias and tensile strain improve photocatalytic performance.

Strain tuning adjusts band edges and reduces H adsorption free energy.

Most TMDC monolayers become ideal HER catalysts under optimal strain.

Abstract

Low-dimensional transition metal dichalcogenides (TMDC) exhibit great photocatalytic performance and tunability. In this work, using first-principles simulations based on density functional theory (DFT), we demonstrate that external electric bias can be employed to further improve the photocatalytic hydrogen production efficiency of the six AB$_{2}$ (A=Mo, W and B=S, Se, Te) TMDC monolayers by exploiting their piezoelectric response. In particular, when subjected to a proper amount of electrically induced tensile biaxial strain, most TMDC monolayers turn into potentially ideal photocatalyst towards the hydrogen evolution reaction (HER). The beneficial effects of introducing tensile biaxial strain on the TMDC monolayers are not limited to the reduction of the band gap and proper adjustment of the band edge positions, but also to the modification of the H adsorption free energy in such a way that the HER reaction is noticeably favored.