Microstructure-dependent photoelectrochemical and photocatalytic properties of BiOI

In this study, we demonstrate that the photoelectrochemical and photocatalytic properties of BiOI strongly depend on their microstructures. Compared to BiOI nanoplates with thickness <100 nm, BiOI nanoplate microspheres of 2-5 mu m in size exhibited a superior photocatalytic methyl orange degradation performance, but their photocurrent was only 1/11 of that of BiOI nanoplates. The insights into the microstructure-dependent difference are discussed in detail. We think that the higher photocurrent of BiOI nanoplates film lies in more photogenerated electrons because of narrower band gap and less surface defects and better electron transport between nanoplates owing to good connectivity, while the superior photocatalytic degradation activity of BiOI nanoplate microspheres is attributed to their better methyl orange adsorption ability and abundant surface reaction sites as well as more powerful oxidative ability because of larger band gap. This study provides some clues to enhance photoelectrochemical property and photocatalytic activity of semiconductor materials.