Structural evolution of cobalt oxide–tungsten oxide nanowire heterostructures for photocatalysis

• Heterostructures comprised of Co3O4 nanowires coated with WO3.
• The dry process for fabrication combines thermal method and sputtering.
• Heterostructures were studied for their composition and morphology.
• Band gap energy and photocatalytic ability of heterostructures were studied.

Tungsten oxide (WO3) and cobalt tungstate (CoWO4) decorated one-dimensional cobalt oxide (Co3O4) nanowire heterostructures were fabricated through a facile and cost-effective approach. The process includes vapor–solid growth of cobalt oxide nanowires via a thermal oxidation method and sputtering coating of tungsten oxide on the standing Co3O4 nanowires. To further modulate the structure and/or morphology and improve the crystallization of tungsten oxide, the product was subjected to a post-annealing process, which resulted in free-standing Co3O4–WO3/CoWO4 multi-component nanowire heterostructures. The crystal structures, morphologies, and chemical composition at each fabrication stage were studied in detail using microscopy and spectroscopy. The investigation for the first time showed the dry processing route for formation of such novel nanowire heterostructures. The photocatalytic performance and behavior of such nanowire heterostructures were further demonstrated for the degradation of water-contaminating organics (via a phenol photodegradation process). The photocatalytic efficiency of the final nanowire heterostructures was estimated to be increased by ∼30% for both visible and UV illumination as compared with the as-produced Co3O4 nanowires.

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