Dealloying of Few Coating: From Disorder to Order

Oxide semiconductors are widely used as photocatalysts in environmental purification as well as energy harvesting and transformation. Thanks to its narrow energy band gap, WO₃ (2.7eV) and Fe₂O₃ (2.2eV)  is recognized as one of the most promising n-type semiconductors resistant to photocorrosion in acidic and alkaline aqueous solution respectively, and shows interesting properties both in visible light absorption and its good charge transport abilities. To pursue higher quantum efficiency, nanostructures are a favorable choice, many WO₃ and Fe₂O₃ nanostructures in the form of powders, nanowires, nanorods, nanobelts and nanochannels have been synthesized and reported.

Precisely controlled conditions and complicated fabrication methods have been needed in the preparation of WO₃ and Fe₂O₃-based photocatalysts for water decomposition. Dealloying was considered to be a simple, mild and economical method to fabricate nanostructures, such as nanoporous structures, nanowires, nanocages, etc. As determined by their chemical potentials, the more active (less noble) component is selectively dissolved, while the other phase represents simultaneously a self-assembling action, which is controlled by atom diffusion and the materials’ intrinsic properties.

In this work, we propose a more facile and efficient way to nanostructures by dealloying the as-electrodeposited FeW amorphous alloy coating  in an acidic and alkaline environments. It was found that highly ordered WO₃ and Fe₂O₃nanoflake arrays were successfully synthesized and remarkable photoelectrochemical performance in water splitting of the novel nanostructure photoanode can be achieved by this disorder to order transformation.

References

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