Preparation and photocatalytic activity of porous Bi2O3 polymorphisms

• Porous Bi2O3 catalysts were prepared with urea by the sol–gel method.
• The Bi2O3 changed from α-phase to mixture of β-phase and γ-phase using urea.
• The band gap was shifted from 2.8 eV to 3.0 eV using urea.
• The amount of H2 produced increased with the addition of urea.
• The H2 evolution was related to large surface area and small PL intensity.

In this study, porous Bi2O3 catalysts were prepared by the sol–gel method, and the effects of polymorphism and pore structure on the photocatalytic activity for hydrogen evolution using Bi2O3 were investigated. The mixtures of β- and γ-Bi2O3 prepared using urea showed larger specific surface areas and higher activities for hydrogen evolution than α-Bi2O3 prepared without urea.