Post-illumination activity of Bi2WO6 in the dark from the photocatalytic memory effect

Photocatalysts with the photocatalytic memory effect could resolve the intrinsic activity loss of traditional photocatalysts when the light illumination is turned off. Due to the dual requirements of light absorption and energy storage/release functions, most previously reported photocatalysts with the photocatalytic memory effect were composite photocatalysts of two phase components, which may lose their performance due to gradually deteriorated interface conditions during their applications. In this work, a simple solvothermal process was developed to synthesize Bi2WO6 microspheres constructed by aggregated nanoflakes. The pure phase Bi2WO6 was found to possess the photocatalytic memory effect through the trapping and release of photogenerated electrons by the reversible chemical state change of W component in the (WO4)(2-) layers. When the illumination was switched off, Bi2WO6 microspheres continuously produced H2O2 in the dark as those trapped photogenerated electrons were gradually released to react with O-2 through the two-electron O-2 reduction process, resulting in the continuous disinfection of Escherichia coli bacteria in the dark through the photocatalytic memory effect. No deterioration of their cycling H2O2 production performance in the dark was observed, which verified their stable photocatalytic memory effect.

Automated summary

A simple solvothermal process was used to synthesize Bi2WO6 microspheres with photocatalytic memory effect, which could continuously produce H2O2 in the dark to disinfect bacteria by releasing trapped photogenerated electrons. The stable cycling performance of H2O2 production in the dark validated the stable photocatalytic memory effect of Bi2WO6 microspheres.