# Au-Co Alloy Nanoparticles Supported on ZrO2 as an Efficient Photocatalyst for the Deoxygenation of Styrene Oxide

## TL;DR

Researchers developed a new photocatalyst using Au-Co alloy nanoparticles on ZrO2 to efficiently convert styrene oxide into useful chemicals like styrene and styrene glycol under visible light.

## Contribution

A new Au-Co/ZrO2 photocatalyst was developed for efficient and selective deoxygenation of styrene oxide under visible light.

## Key findings

- Au-Co/ZrO2 catalysts achieved styrene conversion even at temperatures below 60 °C.
- Increasing temperature favored the production of styrene glycol over styrene.
- SERS and EPR studies revealed changes in reaction mechanisms with varying cobalt ratios.

## Abstract

Epoxide deoxygenation by photocatalysis was explored using Au-Co alloy nanoparticles supported on ZrO2 under visible light irradiation. The active metals were deposited on commercial monoclinic ZrO2 by chemical impregnation to achieve controlled mass ratios of gold and cobalt in the alloy nanoparticles. The characterisation of the alloy nanoparticles confirmed the technique produced an average particle size of 4.50 ± 0.29 nm. Catalysts containing pure 3% Au and different Au-Co metal ratios attached to the ZrO2 induced the deoxygenation of styrene oxide in an isopropanol solvent medium. Only 20 mg of pure Au/ZrO2 catalyst gave a 99% yield of styrene at an 80 °C temperature within 16 h under visible light irradiation (400–800 nm). Au-Co/ZrO2 catalysts generally induced conversion to styrene under the same conditions below 60 °C. Above 60 °C, a new reaction pathway was observed to favour a different product over Au-Co/ZrO2, which was identified as styrene glycol. This study developed a new approach to the synthesis of styrene glycol, a molecule that has many useful applications in the chemical and polymer industries. Surface-enhanced Raman spectroscopic (SERS) studies and electron paramagnetic resonance spectroscopic (EPR) studies identified changes in the reaction mechanism and pathway upon increasing the cobalt molar ratio in the Au-Co alloy catalysts.