Protonated Branched Polyethyleneimine Induces the Shape Evolution of BiOCl and Exposed {010} Facet of BiOCl Nanosheets

Protonated branched polyethyleneimine (BPEI) are employed to induce the shape evolution of BiOCl and facet exposure of BiOCl nanosheets through the interaction of protonated positive charges and negative charges stemmed from the {010} facet of BiOCl. During the synthesis process, vital factors including the concentration of protonated BPEI, protonated ability of BPEI caused by the concentration of chlorine ions (Cl–), and solvent for the shape and exposure facet of BiOCl are investigated detailly. The shape and phase of the resultant BiOCl is highly determined by the concentration of added BPEI. That is, when increasing the concentration of BPEI from 0 to 14.29 g/L, the shape of resulting products is evolved from three-dimensional (3D) assembled flowers to two-dimensional (2D) nanosheets. Especially, well-defined 2D BiOCl nanosheets with {010} exposed facets are obtained at a fixed concentration of BPEI (3.57 g/L). Furthermore, even fixing this concentration of BPEI, the protonated ability of BPEI is boosted by altering the concentration of Cl– sources and substitutive solvent of aqueous, resulting in increased concentration of vacancies on the surface of BiOCl (such as BiOCl-Cl3 and BiOCl-AQ) nanosheets. These BiOCl nanosheets with increased vacancies present dramatically enhanced photoreduction efficiency of Cr(VI) removal under simulated solar light irradiation. This work provides a valuable and facile route to design the adjustable shape and exposed facet of BiOCl nanosheets for photocatalysis.