Alkali-Assisted Solvothermal Synthesis of I-deficient Nanoplatelet BiOI Microflowers with Enhanced Visible-Light Photocatalytic Performance for Degradation of Organic Pollutants

I-deficient nanoplatelet bismuth oxyiodide (BiOI) microflowerswere successfully synthesized via a one-pot solvothermal method usingNaOH. Results demonstrated that OH- played a keyrole in regulating the morphology, pore structure, and energy bandstructure of the prepared samples. As the volume of NaOH increased,the size of the BiOI microflowers gradually decreased, and the specificsurface area and pore volume increased, providing more accessibleactive sites for photocatalytic reactions. Additionally, some iodineatoms in B-7 (i.e., 7 mL of a 1.0 M NaOH solution was added duringthe synthesis process) were replaced by hydroxide ions, affordingB-7 with slight defects. The loss of iodine atoms shifted the valenceband maximum (VBM) from 1.372 eV for the pristine BiOI (B-0) to 1.596eV for I-deficient BiOI (B-7). The lowered VBM provides more oxidativeholes, which is favorable for the oxidation reaction. The photocatalyticactivities of the prepared samples were evaluated via the photodegradationof various organic pollutants, such as methyl orange, Rhodamine B,and phenol, under visible light. Owing to the higher surface areaand pore volume, lower VBM, and presence of surface defects, B-7 exhibitedthe highest degradation efficiency among all of the samples.