Vertically Aligned Nanosheets-Array-like BiOI Homojunction: Three-in-One Promoting Photocatalytic Oxidation and Reduction Abilities

An unprecedented BiOI homojunction constructed by BiOI nanosheets and BiOI microplates was developed through charge-induced in situ precipitation assembly under ambient conditions. BiOI nanosheets are found vertically assembling on the surface of BiOI microplates to form a nanosheets-array-like hierarchical architecture due to electrostatic interaction. This BiOI homojunction casts not only increased adsorption, but also profoundly boosted photocatalytic performance for decomposition of multiplicate organic contaminants and water splitting into H-2 evolution, contrasting with the individual nanosheets or microplates. The pronounced performance is ascribed to the synergistic effect from the following three aspects: (1) nanosheets-array-like hierarchical architecture endues BiOl homojunction increased surface area, which favors adsorption of reactants and generation of reactive sites; (2) the BiOl nanosheets forest induces an enhanced multiple reflection and scattering effect of light, engendering more photoinduced charge carriers; (3) more critically, band alignment in the BiOI homojunction impels the electron and hole separately to BiOI nanosheets and BiOl microplates, drastically promoting surface charge transfer efficiency and elevating the carrier density. The present work may furnish a new concept of designing efficient homojunctions with multiple advantageous factors and unique architectures in solar energy conversion.