First Principles study of Photocatalytic Water Splitting in BO Monolayer: Effect of Strain and Surface Functionalization

TL;DR

This study demonstrates that functionalized BO monolayers, especially with double atom decorations, can be engineered via strain and surface modifications to exhibit visible-light photocatalytic activity for water splitting, promising for hydrogen production.

Contribution

First principles calculations reveal how strain and surface functionalization enhance BO monolayers' photocatalytic properties for water splitting.

Findings

Double atom decoration shifts optical absorption into visible range

Strain tuning adjusts band gap and alignment

All configurations are thermodynamically stable

Abstract

Light element based two dimensional (2D) materials are promising photocatalysts for hydrogen production via water splitting. Boron oxide (BO) is a recently synthesized 2D monolayer which has yet to be thoroughly explored for its potential applications. In this article, using first principles calculations, we report, for the first time, the visible-light photocatalytic activity of a BO monolayer for water splitting under mechanical strain and surface modification with single- and double-atom decorations (C, N, Si, Ge, P, As). The pristine BO monolayer exhibits an indirect band gap of 3.8 eV with band edges spanning the water redox potentials, but its optical absorption lies in the UV region (~ 4.5 eV). Strain engineering tunes the band gap and band alignment with a minimal shifting in the optical absorption (~0.5 eV). Single atom decoration produces a metallic state for elements like N, P, As, and an insulating state for single C, Si, Ge with a partial shifting in optical absorption. In contrast, double atom decoration produces substantial band gap reduction, improved band alignment, a pronounced red-shift in optical absorption into the visible range (1.6 to 3.2 eV) thus satisfying the criteria for water splitting. The stability of all the adsorbed configurations was confirmed by negative formation energy and ab-initio molecular dynamics simulations. These findings suggest BO monolayer functionalization can improve photocatalytic efficiency, providing hydrogen generation insights.