title: Tuning the surface oxygen concentration of {111} surrounded ceria nanocrystals for enhanced photocatalytic activities.
abstract: For oxide semiconductors, the morphology, particle size and oxygen vacancies are usually considered as key influential parameters for photocatalytic degradation of organic pollutants/dyes. It is widely accepted that cation doping not only modifies their phase and microstructures but also introduces variations in oxygen vacancy concentration. Herein, we report the fabrication of sub-10 nm sized pure and indium doped CeO2 nanocrystals (NCs) via a facile, green hydrothermal method for the investigation of photocatalytic activities. X-ray diffraction and transmission electron microscopy were employed to examine the crystal phase and morphology of the as-prepared nanocrystals. Raman and X-ray photoelectron spectroscopy techniques were implemented to investigate the presence and variations in oxygen vacancy concentration in un-doped and indium doped CeO2 nanocrystals. The photocatalytic activity results revealed that 10 at% doping is the optimal indium doping level to demonstrate superior dye removal efficiency (∼40%) over un-doped and doped CeO2 NCs. Moreover, the 10% In-doped CeO2 nanocrystals expressed excellent cycling stability and superior photocatalytic performance toward other dye pollutants. Finally, on the basis of our findings, a possible photocatalytic mechanism in which indium doping can generate more surface oxygen vacancies in the ceria lattice which delay the electron-hole recombination rates, thus increasing the lifetime of electron-hole separation for enhanced photocatalytic performances was proposed.
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW, Australia. a.younis@unsw.edu.au d.chu@unsw.edu.au.
authors.forename: Adnan
authors.initials: A
authors.lastname: Younis
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW, Australia. a.younis@unsw.edu.au d.chu@unsw.edu.au.
authors.forename: Dewei
authors.initials: D
authors.lastname: Chu
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW, Australia. a.younis@unsw.edu.au d.chu@unsw.edu.au.
authors.forename: Yusuf Valentino
authors.initials: YV
authors.lastname: Kaneti
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW, Australia. a.younis@unsw.edu.au d.chu@unsw.edu.au.
authors.forename: Sean
authors.initials: S
authors.lastname: Li