A Simple Microplate Assay for Accelerated Photocatalytic Activity Evaluation

Photocatalysis has been extensively studied for its potential to harness abundant sunlight energy, yet exploration has been limited by the time and effort required for performance evaluation. To screen candidate materials, including the elements across the entire periodic table, throughput must be improved while minimizing labor. In this study, we introduce a simple, labor-saving, high-throughput assay for evaluating photocatalyst activity utilizing a 96-well microplate. The protocol provides a streamlined workflow that encompasses weighing, microplate preparation, light irradiation, spectroscopic measurement, and reaction rate analysis. Importantly, this protocol removes the bottleneck of separating photocatalyst powders from the dye solution throughout the cycles of light irradiation and spectral measurements, which significantly improves the throughput and saved labor. As a foundation for this method, we investigated the relationship between the coexistence of dye and powder against the resulting apparent absorbance and the temporal profile of absorbance during the photocatalytic reaction. From the result, we provide guidelines for determining versatile amounts of the photocatalyst and dye depending on the balance between measurement accuracy and throughput. As the method relies on the additivity of absorption and scattering within a defined optical density window, it is not restricted to a particular dye. This assay enables photocatalyst performance evaluation for ∼500/day, which holds promise for exploring the vast material space across the periodic table, significantly broadening the horizons for discovering novel photocatalysts.