Hydroxyl-regulated BiOI nanosheets with a highly positive valence band maximum for improved visible-light photocatalytic performance

Abstract Bismuth iodide oxide (BiOI) as visible-light photocatalysts are widely applied to photodegradation reactions. Although surface atom tailoring has been actively used to modify electronic structures for improving photocatalytic activity, the functional groups used in improving surface reaction sites and surface band structure of BiOI has been largely overlooked. Here we report a new surface engineering strategy using deliberately selected organic solvents to tailor the surface structures and photocatalytic property of the BiOI nanosheets. Interestingly, the BiOI nanosheets modified by glycerol which contains abundant hydroxyl groups exhibit a more positive surface valance band maximum than that of BiOI synthesized in water. Consequently, the oxidation ability of photogenerated holes from hydroxyl-regulated BiOI is substantially improved, evident by the highly effective degradation of phenol and organic dyes under visible light, and a photoelectrochemical water splitting activity. The new findings provide a new strategy in tailoring surface atom structure by specific functional groups towards highly efficient photocatalysts.