Structurally Engineered Two-Dimensional Layered Bismuth Oxyiodide Surfaces as a "Dip Photocatalyst" for a Photocatalytic Reaction

Abstract

A simple protocol for the synthesis of two-dimensional (2D) layered bismuth oxyiodide (BiOI), at room temperature without any stabilizer, with well-defined exposed {001} facets and tunable morphologies (bowl shapes, square-sheet shape, and star shapes) was developed. The surface topographical analysis reveals layer-by-layer (LBL) stacking of ultrathin sheets of BiOI with a thickness of 1.8 nm. Transmission electron microscopy and selected area electron diffraction analysis established the exposed plane as {001}. A free-standing "dip photocatalyst"was fabricated by spin coating of bismuth oxyiodide (BiOI) and poly(vinyl alcohol) (PVA) aqueous solution on a polystyrene (PS) sacrificial substrate. Free-standing composite film of BiOI-PVA with a thickness of several micrometers was achieved by dissolving the polystyrene films in toluene. The photocatalytic activity of the BiOI-PVA "dip photocatalyst"was examined by the degradation of rhodamine B under a low power visible light source. Significantly, this approach to the formation of the "dip photocatalyst"is convenient to evaluate its fate through multiple reuses.