Few-Layer Thin-Film Metallic Glass-Enhanced Optical Properties of ZnO Nanostructures

Preparation and characterization of ternary composite photocatalyst for degradation of oxytetracycline hydrochloride in seawater under visible light

Oxytetracycline hydrochloride is the most widely used veterinary antibiotic in aquaculture. The presence of large amounts of residual antibiotics in aquaculture wastewater harms the ecological environment. In this study, the ternary composite of Zn_0.75Mn_0.75Fe_1.5O₄/ZnFe₂O₄/ZnO (ZMF-ZF-Z) photocatalyst was prepared by the coprecipitation method for degradation of oxytetracycline hydrochloride in marine aquaculture wastewater. The crystal phase, structure, morphology, elemental composition, element content, and optical properties of photogenerated electron-hole pairs of catalyst were characterized by XRD, SEM, EDS, UV-VIS (DRS), PL spectroscopy, and other test methods. The results showed that ZMF-ZF-Z photocatalyst had a larger response range of visible light than pure ZnO, which can absorb more natural light. During the process of the experiment, the photocatalytic effect of Z ZMF-ZF-Z photocatalyst was almost no weakening after 5 times reuse, which means quite good stability of the photocatalyst. Under the visible light irradiation, the degradation rate of oxytetracycline hydrochloride in seawater was 77.11% with ZMF-ZF-Z photocatalyst, which was about 3 times higher than that of pure ZnO, and the photocatalytic activity was significantly improved. This research provides a scientific and effective method for degrading antibiotics in seawater in actual production and life.

Enhancement of UV Photodetection Properties of Hierarchical Core-Shell Heterostructures of a Natural Sericin Biopolymer with the Addition of ZnO Fabricated on Ultra-Nanocrystalline Diamond Layers

A novel self-assembled hierarchical heterostructure is derived from cocoon-derived sericin biopolymer (CSP) biowaste with ZnO deposited on ultra-nanocrystalline diamond (UNCD) substrates using a scalable chemical deposition technique. Then, high-performance long-life UV photodetectors are fabricated using this hybrid sericin, diamond, and ZnO (SDZ) nanostructure. The microstructural analysis reveals a several nanometer-thick CSP shell coated with a highly uniform ZnO nanorod (ZNR) array grown on the UNCD substrate. The CSP shell also contains columnar nanograins on top of the ZNR as well as vertical sidewalls with unique alignments. The hierarchical core-shell SDZ heterostructures reveal superior UV diode performance, with an ultrahigh UV switching ratio of 1.1 × 10⁵ at 5 V, an increase of up to 49 900% greater than that of as-grown ZNRs (220). High UV responsivity is observed around 3.6 A W^-1 under 365 nm UV light illumination. The perfect distribution of the sericin in the ZNRs on the UNCD substrates resulted in the ultrafast electron-hole recombination. The sericin dopants and the UNCD interlayer enabled the device to reach new energy levels in the conduction band, with the reduced barrier height allowing for improved charge carrier transportation during UV light illumination. It is believed that the sericin dopants and the UNCD layer increased the UV adsorptivity and the amount of conducting carbon dopants within the ZNRs was sufficient for s0tability. These noteworthy features make the SDZ heterostructures promising candidates for the fabrication of cost-efficient biopolymers and UNCD hybrid-based UV photodetectors.

Translucent Photodetector with Blended Nanowires-Metal Oxide Transparent Selective Electrode Utilizing Photovoltaic and Pyro-Phototronic Coupling Effect

ZnO is a potential candidate for photodetection utilizing the pyroelectric effect. Here, a self-biased and translucent photodetector with the configuration of Cu₄ O₃ /ZnO/FTO/Glass is designed and fabricated. In addition, the pyroelectric effect is effectively harvested using indium tin oxide (ITO), silver nanowires (AgNWs), and a blend of AgNWs-coated ITO as the transparent selective contact electrode. The improved rise times are observed from 1400 µs (bare condition; without the selective electrode) to 69, 60, 7 µs, and fall times from 720 µs (bare condition) to 80, 70, 10 µs for corresponding ITO, AgNWs, and AgNWs-coated ITO contact electrodes, respectively. Similarly, the responsivity and detectivity are enhanced by about 4.39 × 10⁷ and 5.27 × 10⁵ %, respectively. An energy band diagram is proposed to explain the underlying working mechanism based on the workfunction of the ITO (4.7 eV) and AgNWs (4.57 eV) as measured by Kelvin probe force microscopy, which confirms the formation of type-II band alignment resulting in the efficient transport of photogenerated charge carriers. The functional use of the transparent selective contact electrode can effectively harness the pyro-phototronic effect for next-generation transparent and flexible optoelectronic applications.

Silver-Nanowire-Embedded Transparent Metal-Oxide Heterojunction Schottky Photodetector

We report a self-biased and transparent Cu₄O₃/TiO₂ heterojunction for ultraviolet photodetection. The dynamic photoresponse improved 8.5 × 10⁴% by adding silver nanowires (AgNWs) Schottky contact and maintaining 39% transparency. The current density-voltage characteristics revealed a strong interfacial electric field, responsible for zero-bias operation. In addition, the dynamic photoresponse measurement endorsed the effective holes collection by embedded-AgNWs network, leading to fast rise and fall time of 0.439 and 0.423 ms, respectively. Similarly, a drastic improvement in responsivity and detectivity of 187.5 mAW^-1 and of 5.13 × 10⁹ Jones, is observed, respectively. The AgNWs employed as contact electrode can ensure high-performance for transparent and flexible optoelectronic applications.