Influence of annealing ambient on the structure, photoluminescence and photocatalytic activity of low temperature grown ZnO nanowires

• ZnO nanowires are synthesized via a low-temperature (90 °C) hydrothermal route.
• There exist graphitic carbons on the ZnO nanowires after vacuum annealing.
• The PL intensity of ZnO nanowires with the graphitic carbons is significantly reduced.
• The photocatalytic activity of ZnO nanowires with graphitic carbons is enhanced.

ZnO nanowires were synthesized via a low-temperature (90 °C) hydrothermal route on glass substrates pre-deposited with a ZnO seed layer. The influence of different annealing ambient conditions (air or vacuum) on the structure, photoluminescence and photocatalytic activity of ZnO nanowires was investigated by Raman spectroscopy, X-ray diffraction, photoluminescence (PL) and photochemical reactions etc. It was found that there existed graphitic carbons on the surfaces of ZnO nanowires after vacuum annealing. The PL intensity of ZnO nanowires with the graphitic carbons was significantly reduced while the photocatalytic activity was enhanced, indicating that the graphitic carbons could decrease the recombination probability of photo-induced carriers.

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