Computational assessment of non-polar and polar GaP terminations for photoelectrochemical water splitting

TL;DR

This study uses ab initio molecular dynamics to analyze water interfaces of GaP surfaces, assessing their suitability for photoelectrochemical water splitting and proposing improvements for better PEC performance.

Contribution

It provides detailed insights into the water interface properties of GaP polar and non-polar terminations, informing strategies to enhance PEC water splitting efficiency.

Findings

Non-polar (110) termination shows favorable band alignment.

Polar (001) termination exhibits distinct interfacial structural properties.

Recommendations for surface modifications to improve PEC performance.

Abstract

With photoelectrochemical water splitting being one of the most promising approaches for clean energy production and storage, the search for efficient photoelectrode materials is greater than ever. Gallium phosphide (GaP) is a well-established semiconductor with suitable band edge positions that has already been successfully employed in photoelectrochemical solar cells. However, to utilize it as efficiently as possible, a proper understanding of its properties when interfaced with water is required, and this is currently lacking. In this work we use ab initio molecular dynamics simulations to study the properties of the aqueous interfaces of various GaP non-polar (110) and polar (001) terminations. We calculate their band alignment with respect to the standard hydrogen electrode potential and investigate their interfacial structural properties. Based on these properties we assess the capability of the various terminations to catalyze the reactions associated with water splitting and propose approaches for improving the performance of GaP for application in PECs.