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Nanocomposite films of Au-modified bismuth oxide (Au-Bi 2 O 3 ) were synthesized via anodic electrodeposition of Bi combined with a galvanic replacement reaction. First, Bi 2 O 3 was prepared by the anodic oxidation of pre-electrodeposited Bi films in 0.1 M NaOH electrolyte. The amount of metallic bismuth in Bi 2 O 3 was tuned by controlling the oxidation time or deposition potential. Thus-prepared Bi-Bi 2 O 3 composite was converted to Au-Bi 2 O 3 by galvanically replacing metallic Bi with Au from an aqueous HAuCl 4 solution. The photocatalytic activity of the Au-Bi 2 O 3 nanocomposite for decomposition of methyl orange dye was superior to that of the bare Bi 2 O 3 counterpart under UV as well as visible light illumination.

A Au-BiVO(4) nanocomposite is synthesized by a two-step strategy involving anodic electrodeposition combined with in situ galvanic replacement. First, a BiVO(4) layer is prepared by the anodic oxidation of pre-electrodeposited Bi film in a VO(4)(3-) containing electrolyte. Thus-prepared BiVO(4) film contains excess metallic Bi, which is then galvanically replaced with Au from an aqueous HAuCl(4) solution, resulting in the Au-BiVO(4) composite in the second step. Optical, photoelectrochemical and photocatalytic properties are investigated by using X-ray diffraction, energy-dispersive X-ray analysis, diffuse reflectance spectrometry, and photoelectrochemical analyses. The visible-light photocatalytic activity of the Au-BiVO(4) composite is evaluated using the decomposition of methyl orange dye and is superior to the bare BiVO(4) film counterpart.

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