Significant CO2 photoreduction on a high-entropy oxynitride

TL;DR

This study demonstrates that a high-entropy oxynitride photocatalyst significantly improves CO2 photoreduction efficiency due to enhanced light absorption, charge separation, and surface adsorption, outperforming existing catalysts.

Contribution

Introduction of a novel high-entropy oxynitride material as an effective and stable photocatalyst for CO2 reduction, surpassing traditional catalysts in efficiency.

Findings

Higher CO2 to CO conversion than benchmark catalysts.

Good chemical stability of the oxynitride photocatalyst.

Enhanced light absorption and charge separation capabilities.

Abstract

CO$_2$ photoreduction on photocatalysts is a nature-friendly solution to decrease the CO$_2$ amount, but the method still has low efficiency because of difficult separation and easy recombination of charge carriers in available catalysts. In this study, a high-entropy oxynitride was introduced as an active photocatalyst for photoreduction. The material had a chemical composition of TiZrNbHfTaO$_6$N$_3$ and was produced by a high-pressure torsion method followed by oxidation and nitriding. It showed higher photocatalytic CO$_2$ to CO conversion compared to corresponding high-entropy oxide, benchmark photocatalyst P25 TiO$_2$, and almost all catalysts introduced in the literature. The high activity of this oxynitride, which also showed good chemical stability, was attributed to the large absorbance of light and easy separation of electrons and holes, the low recombination of charge carriers, and the high CO$_2$ adsorption on the surface. These findings introduce high-entropy oxynitrides as promising photocatalysts for CO$_2$ photoreduction.