Prediction of (TiO2)x(Cu2O)y Alloys for Photoelectrochemical Water Splitting

TL;DR

This study uses computational methods to predict new TiO2-Cu2O alloys with improved visible light absorption and suitable band edges for efficient photoelectrochemical water splitting.

Contribution

It introduces a computational approach combining global optimization and first-principles calculations to identify promising TiO2-Cu2O alloys for solar water splitting.

Findings

TiO2-Cu2O alloys have similar local environments to bulk oxides.

Predicted optical band gaps around 2.1 eV, better for visible light absorption.

(TiO2)2(Cu2O) has the lowest formation energy and suitable band edges for water splitting.

Abstract

The formation of (TiO2)x(Cu2O)y solid-solutions are investigated using a global optimization evolutionary algorithm. First-principles calculations based on density functional theory are then used to gain insight into the electronic properties of these alloys. We find that: (i) Ti and Cu in (TiO2)x(Cu2O)y alloys have similar local environments as in bulk TiO2 and Cu2O except for (TiO2)(Cu2O) which has some trigonal-planar Cu ions. (ii) The predicted optical band gaps are around 2.1 eV (590 nm), thus having much better performance for the absorption of visible light compared with both binary oxides. (iii) (TiO2)2(Cu2O) has the lowest formation energy amongst all studied alloys and the positions of its band edges are found to be suitable for solar-driven water splitting applications.