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) microflowers were successfully synthesized via a one-pot solvothermal method using NaOH. Results demonstrated that OH – played a key role in regulating the morphology, pore structure, and energy band structure of the prepared samples. As the volume of NaOH increased, the size of the BiOI microflowers gradually decreased, and the specific surface area and pore volume increased, providing more accessible active sites for photocatalytic reactions. Additionally, some iodine atoms in B-7 (i.e., 7 mL of a 1.0 M NaOH solution was added during the synthesis process) were replaced by hydroxide ions, affording B-7 with slight defects. The loss of iodine atoms shifted the valence band maximum (VBM) from 1.372 eV for the pristine BiOI (B-0) to 1.596 eV for I-deficient BiOI (B-7). The lowered VBM provides more oxidative holes, which is favorable for the oxidation reaction. The photocatalytic activities of the prepared samples were evaluated via the photodegradation of various organic pollutants, such as methyl orange, Rhodamine B, and phenol, under visible light. Owing to the higher surface area and pore volume, lower VBM, and presence of surface defects, B-7 exhibited the highest degradation efficiency among all of the samples.