2, University of California, Merced, Merced, California, United States
3, Universidad Nacional Autónoma de México, Mexico City, , Mexico
4, Universidad Nacional Autónoma de México, Mexico City, , Mexico
Semiconductor photocatalysis is a promising route for the use of solar energy for the cost-effective treatment of water for the decomposition of contaminants and other applications, including H2 production, organic chemical synthesis and the conversion of CO2 to fuel. Bismuth oxides are promising for these applications due to the wide availability of bismuth from other industrial processes and their relatively benign impact on the environment. Bismuth oxide halides (BiOX, where X = F, Cl, Br and I) may offer improvements in any of these aspects: band gap narrowing, change to an indirect band gap and reduced electron-hole recombination rates.
Here, we discuss the investigation of a facile, scalable route for the production of bismuth oxychloride nanoparticles for solar photocatalytic water treatment from a simple solution treatment of Bi2O3. Depending on chlorine to bismuth stoichiometry, and the time of reaction, different nanoscale morphologies can be obtained. Under low Cl:Bi stoichiometry, nanosheets of ~5 nm thickness and up to 1 mm in diameter are formed; while, under high Cl:Bi stoichiometry, nanoplates of ~20 nm thickness and ~200 nm in diameter are formed that become thicker with reaction time. The control of particle morphology through reaction parameters and its effect on optical properties and photocatalytic efficiency are discussed. The phase transformation mechanism, and its application to the synthesis of more complex bismuth based nanostructures are also considered.