Hydrolysis of urea induces the formation of bismuth-rich Bi4O5I2 nanosheets with promoted visible-light photoreduction of Cr (VI).

• Bismuth-rich Bi 4 O 5 I 2 nanosheets were prepared through progressive hydrolysis of urea in a facile solvothermal route. • Adjusting the sufficient and progressive hydrolysis of urea in ethylene glycol is vital step. • Resulted Bi 4 O 5 I 2 nanosheets exhibited superior visible-light photoreduction activity of Cr (VI). Bismuth-rich Bi 4 O 5 I 2 nanosheets were prepared through progressive hydrolysis of urea in a facile solvothermal route, which is different from the conventional strategies of pH adjusting or calcination. To promote the hydrolysis of urea for the formation of Bi 4 O 5 I 2 nanosheets, the type of solvents and urea concentration were the distinctive roles. Especially, urea concentration over 1.0 g but less than 3.0 g in the solvent of ethylene glycol could boost the formation of Bi 4 O 5 I 2 nanosheets. Furthermore, the resulted Bi 4 O 5 I 2 nanosheets possessing more negative conductive band level of −1.02 eV showed superior visible-light photoreduction activity of Cr (VI) due to the efficient separation of charge carriers. [ABSTRACT FROM AUTHOR]