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Recent advances in Ag-doped WO3 nanofibers have provided an opportunity to fabricate high quality and low-cost surface-enhanced Raman scattering (SERS) substrates. This work studied the performance and shelf-life of Ag-doped WO3 nanofiber-based substrates. Methylene blue (MB) molecules were used as analytical references. The prepared substrates were stored in ambient air at room temperature for the duration of 12 months. The Raman enhancement factor (EF) of freshly prepared sample was calculated to be 6.2 × 105. In the first 6 months, a small decrease in EF was observed. The EF was found to significantly decrease after samples were stored for 12 months. After 12 months, the relative standard deviations (RSD) of Raman signals changed from 10.35% to 50.29%, indicating non-uniform Raman enhancements at different locations of the sample. These suggested agglomerations of Ag nanoparticles, which deteriorated the Raman enhancement effect, after samples were stored for a prolonged period.

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This work reports the fabrication and photoelectrochemical response of titanium dioxide (TiO2) nanofiber photoelectrode prepared by an electrospinning technique. Transmission electron microscopy (TEM) images reveal that the electropun nanofibers are composed of TiO2 nanoparticles with the average diameter size of 25 nm. The scanning electron microscopy (SEM) image of the photoelectrode confirms the existence of TiO2 nanofiber networks on Ti/Si substrate after the electrode preparation using a doctor-blade technique. The photoelectrochemical performance of TiO2 nanofiber electrode is investigated in comparison with that of TiO2 (Aeroxide P25) nanoparticle electrode. When the TiO2 electrodes are subjected to light illumination at 100 mW/cm2, the maximum photoconversion efficiency (PCE) of 0.95% is obtained at the TiO2 nanofiber electrode while reduced PCE of 0.75% is obtained at the TiO2 nanoparticle electrode.

In this work, WO3 thin films were fabricated by reactive DC magnetron sputtering, and then thermally annealed at 400°C for 2 h under air, low vacuum and high vacuum. After the annealing treatments, the morphology and crystallinity of the WO3 thin films were observed using FE-SEM, GI-XRD and Raman spectroscopy. The optical properties were analyzed by UV-Vis spectroscopy. The results showed the decrease of film thickness under different annealing conditions. In addition, the annealing conditions also affected the crystalline structure at diffraction planes (200) and (002). The transmittance of the WO3 thin films revealed that the annealing treatment at high vacuum led to lower transparency. Furthermore, the WO3 thin film annealed under air produced the highest PEC efficiency. Therefore, this approach offers an alternative strategy for photoelectrochemical (PEC) water splitting application.