Preparation and application of l-cysteine-doped Keggin polyoxometalate microtubes

► l-cysteine-doped polyoxometalate microtubes are prepared. ► Amount of l-cysteine doped in the microtubes can be tuned to some extent. ► Lcys-SiW12 microtubes can be applied as a sensor for detecting alkaline gases. ► This is a proton capture agent-triggered solid-solid redox reaction.