Evaluation of the Oxidation Effect of a Photoredox Catalyst Using Methylene Blue

User Benefits

- The oxidation effect of photoredox catalysts can be quantitatively evaluated by monitoring methylene blue breaching. - Experiments can be conducted using a neutral-density (ND) filter to vary the light exposure per unit time.

Introduction

Photocatalysts promote chemical reactions by absorbing light. Those that are dissolved in a reaction solution are homogeneous photocatalysts, and those that are added to a powder or substrate for a reaction with a solution are heterogeneous catalysts. When photocatalysts are excited by light, they can oxidize (or reduce) substances. This makes homogenous and heterogeneous photocatalysts useful for artificial photosynthesis. In the field of organic synthesis, photoredox catalysts, which are used for oxidation-reduction reactions,* are useful for molecular conversions based on reactionsto light. ISO 10678 specifies using a test based on methylene blue decomposition to quantitatively evaluate the oxidation effect of photocatalysts. Although it is intended for heterogeneous photocatalysts, it is also useful for evaluating the oxidation effect of homogeneous photocatalysts like photoredox catalysts. In this article, a Lightway photoreaction evaluation system was used to evaluate a photoredox catalyst, based on methylene blue breaching. The Lightway photoreaction evaluation system in this article is a unique analytical instrument that integrates an excitation light source for activating photocatalysts with an ultraviolet-visible spectrophotometer for measuring absorption spectra.

December 22, 2024 GMT