Despite a favourable morphology, anodized and ordered TiO2 nanotubes are incapable of showing electrochromic properties in comparison to many other metal oxide counterparts. To tackle this issue, MoO3 of ∼5 to 15 nm thickness was electrodeposited onto TiO2 nanotube arrays. A homogenous MoO3 coating was obtained and the crystal phase of the electrodeposited coating was determined to be α-MoO3. The electronic and optical augmentations of the MoO3 coated TiO2 platforms were evaluated through electrochromic measurements. The MoO3/TiO2 system showed a 4-fold increase in optical density over bare TiO2 when the thickness of the MoO3 coating was optimised. The enhancement was ascribed to (a) the α-MoO3 coating reducing the bandgap of the composite material, which shifted the band edge of the TiO2 platform, and subsequently increased the charge carrier transfer of the overall system and (b) the layered morphology of α-MoO3 that increased the intercalation probability and also provided direct pathways for charge carrier transfer.
A 2D Ga2S3enabled all-optical switch is realized upon a silicon-based on-chip platform. With the unique optical properties of the 2D nanoflakes, the device exhibits excellent switching behaviors driven by visible light at a low power density.
Graphene oxide (GO) nanosheets, as one of the most studied graphene derivatives, have demonstrated an intrinsically strong physisorption-based gas–matter behavior, owing to its enhanced volume–surface ratio and abundant surface functional groups. The exploration of efficient and cost-effective synthesis methods for GO is an ongoing task. In this work, we explored a novel approach to upcycle inexpensive polyethylene terephthalate (PET) plastic waste into high-quality GO using a combination of chemical and thermal treatments based on a montmorillonite template. The obtained material had a nanosheet morphology with a lateral dimension of around ~2 µm and a thickness of ~3 nm. In addition, the GO nanosheets were found to be a p-type semiconductor with a bandgap of 2.41 eV and was subsequently realized as a gas sensor. As a result, the GO sensor exhibited a fully reversible sensing response towards ultra-low-concentration NO2 gas with a limit of detection of ~1.43 ppb, without the implementation of an external excitation stimulus including elevating the operating temperature or bias voltages. When given a thorough test, the sensor maintained an impressive long-term stability and repeatability with little performance degradation after 5 days of experiments. The response factor was estimated to be ~11% when exposed to 1026 ppb NO2, which is at least one order of magnitude higher than that of other commonly seen gas species including CH4, H2, and CO2.
Incorporating Raman micro-spectroscopy into microfluidic units provides certain opportunities for in situ monitoring of bio-systems at the micro scale. Specifically, it allows for the observation of exchange, release and uptake of biochemical components within and in proximity of microorganisms in the highly controlled liquid phase environments of microfluidics. However, such systems are still in infancy and their capabilities need to be explored further. In this paper, the Escherichia coli (E. coli)/glucose bio-system is used for assessing a Raman/microfluidics unit. Two scenarios were used in the observations: the first that includes nutrient rich broth, ideal for E. coli growth, and the second using simplified deionised water.
Fano resonance has an asymmetric and sharp resonance peak near the resonance wavelength, which can effectively enhance the all-optical signal processing capability and realize silicon photonic switches, sensors, and modulators. In this paper, a silicon photonic Fano resonator with Mach-Zehnder interferometer (MZI) structure coupling with micro-ring resonators (MRR) is designed. Two MRRs with different quality factors are coupled with two arms of an MZI, and the coupling zone is composed of two half-ring waveguides. Based on the transfer matrix method, the intrinsic and modulated transfer characteristics of the component are analyzed. By adjusting the optical amplitude and phase of MZIs and tuning the resonance wavelength of two MRRs, Fano resonance spectra are simulated at four output ports with the highest extinction ratios of 56.19 dB and maximum slope rates at 2175.74 dB/nm, and the transmission spectra of Fano resonance at the four output ports are experimentally demonstrated. As the four Fano resonance ports of the designed component have different performances, they can be used for various functions simultaneously. The advantage of the proposed scheme is the improvement of the multiplexing capacity and simultaneous utilization of the muti-port for the Fano resonator. Our four-port Fano resonator can be employed in the fields of optical switching, optical computing, and optical interconnect in the future.
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