Spray pyrolysis deposition and photoelectrochemical properties of n-type BiOI nanoplatelet thin films.
Bismuth oxy-iodide is a potentially interesting visible-light-active photocatalyst; yet there is little research regarding its photoelectrochemical properties. Herein we report the synthesis of BiOI nanoplatelet photoelectrodes by spray pyrolysis on fluorine-doped tin oxide substrates at various temperatures. The films exhibited n-type conductivity, most likely due to the presence of anion vacancies, and optimized films possessed incident photon conversion efficiencies of over 20% in the visible range for the oxidation of I(-) to I(3)(-) at 0.4 V vs Ag/AgCl in acetonitrile. Visible-light photons (λ > 420 nm) contributed approximately 75% of the overall photocurrent under AM1.5G illumination, illustrating their usefulness under solar light illumination. A deposition temperature of 260 °C was found to result in the best performance due to the balance of morphology, crystallinity, impurity levels, and optical absorption, leading to photocurrents of roughly 0.9 mA/cm(2) at 0.4 V vs Ag/AgCl. Although the films performed stably in acetonitrile, their performance decreased significantly upon extended exposure to water, which was apparently caused by a loss of surface iodine and subsequent formation of an insulating bismuth hydroxide layer.
Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science,  The University of Texas at Austin  C0400, 1 University Station, Austin, Texas 78712, United States.
Nathan T
NT
Hahn
Son
S
Hoang
Jeffrey L
JL
Self
C Buddie
CB
Mullins
D001729:Bismuth / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D005740:Gases / Q000737:chemistry; D006358:Hot Temperature; D007454:Iodides / Q000737:chemistry*; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012666:Semiconductors; D013499:Surface Properties
D005740:Gases; D007454:Iodides; D046911:Macromolecular Substances; D008567:Membranes, Artificial; C033301:bismuth oxide; C048121:bismuth iodide; D001729:Bismuth