Energy Band Architecture of a Hierarchical ZnO/Au/CuxO Nanoforest by Mimicking Natural Superhydrophobic Surfaces

Assembling Hollow Cactus-Like ZnO Nanorods with Dipole-Modified Graphene Nanosheets for Practical Room-Temperature Formaldehyde Sensing

Formaldehyde (HCHO) sensing plays a critical role for indoor environment monitoring in smart home systems. Inspired by the unique hierarchical structure of cactus, we have prepared a ZnO/ANS-rGO composite for room-temperature (RT) HCHO sensing, through assembling hollow cactus-like ZnO nanorods with 5-aminonaphthalene-1-sulfonic acid (ANS)-modified graphene nanosheets in a facile and template-free manner. Interestingly, it was found that the ZnO morphology could be simply tuned from flower clusters to hollow cactus-like nanostructures, along with the increase of the reaction time during the assembly process. The ZnO/ANS-rGO-based sensors exhibited superior RT HCHO-sensing performance with an ultrahigh response (68%, 5 ppm), good repeatability, long-term stability, and an outstanding practical limit of detection (LOD: 0.25 ppm) toward HCHO, which is the lowest practical LOD reported so far. Furthermore, for the first time, a 30 m³ simulation test cabinet was adapted to evaluate the practical gas-sensing performance in an indoor environment. As a result, an instantaneous response of 5% to 0.4 ppm HCHO was successfully achieved in the simulation test. The corresponding sensing mechanism was interpreted from two aspects including high charge transport capability of ANS-rGO and the distinct gas adsorbability derived from nanostructures, respectively. The combination of a biomimetic hierarchical structure and supramolecular assembly provides a promising strategy to design HCHO-sensing materials with high practicability.

Novel Core-Sheath Cu/Cu2O-ZnO-Fe3O4 Nanocomposites with High-Efficiency Chlorine-Resistant Bacteria Sterilization and Trichloroacetic Acid Degradation Performance

In order to solve two issues of chlorine-resistant bacteria (CRB) and disinfection byproducts (DBPs) in tap water after the chlorine-containing treatment process, an innovative core-sheath nanostructured Cu/Cu₂O-ZnO-Fe₃O₄ was designed and synthesized. The fabrication mechanism of the materials was then systematically analyzed to determine the component and valence state. The properties of CRB inactivation together with trichloroacetic acid (TCAA) photodegradation by Cu/Cu₂O-ZnO-Fe₃O₄ were investigated in detail. It was found that Cu/Cu₂O-ZnO-Fe₃O₄ displayed excellent antibacterial activity with a relatively low cytotoxicity concentration due to its synergism of nanowire structure, ion release, and reactive oxygen species generation. Furthermore, the Cu/Cu₂O-ZnO-Fe₃O₄ nanocomposite also exhibited outstanding photocatalytic degradation activity on TCAA under simulated sunlight irradiation, which was verified to be dominated by the surface reaction through kinetic analysis. More interestingly, the cell growth rate of Cu/Cu₂O-ZnO-Fe₃O₄ was determined to be 50% and 10% higher than those of Cu/Cu₂O and Cu/Cu₂O-ZnO after 10 h incubation, respectively, manifesting a weaker cytotoxicity. Therefore, the designed Cu/Cu₂O-ZnO-Fe₃O₄ could be a promising agent for tap water treatment.

Directional charge transportation and Rayleigh scattering for the optimal in-band quantum yield of a composite semiconductor nano-photocatalyst

The work propose a novel technique based on wavelength dispersive in situ photoluminescence spectroscopy for diagnosing the wavelength dependent directional charge transportation and Rayleigh scattering enhanced in-band quantum yield.

Electrodeposition of ZnO/Cu2O Heterojunctions on Ni-Mo-P Electroless Coating

Electroless Ni-Mo-P coatings were deposited onto ceramic tiles in order to be employed as electrodes for the electrodeposition of ZnO and Cu2O heterojunction layers. Varying conditions, such as duration, annealing of the electroless coating and applied potential, and duration for ZnO electrodeposition were studied in order to optimize the properties of the ZnO/Cu2O heterojunctions toward improved photoelectrical performance. The coatings were evaluated in terms of morphology, crystalline structure, and by electrochemical and photoelectrical means. The obtained results indicated that a prolonged annealing treatment at low temperature is beneficial to improve the roughness and electrical conductivity of the Ni-Mo-P coating to further enhance the electrodeposition of ZnO. The morphology analysis revealed continuous and homogeneous Ni-Mo-P coatings. The formation of cube-like Cu2O crystals with larger grain size was induced by increasing the deposition duration of ZnO. The properties of ZnO layer are much improved when a higher cathodic potential is applied (−0.8 V) for 1 h, resulting in optimum photoelectric parameters as 1.44 mA·cm−2 for the JSC and 760.23 µV for the VOC value, respectively, for the corresponding heterojunction solar cell.

A versatile strategy for controlled assembly of plasmonic metal/semiconductor hemispherical nano-heterostructure arrays

Recent advances in manipulating plasmonic properties of metal/semiconductor heterostructures have opened up new avenues for basic research and applications. Herein, we present a versatile strategy for the assembly of arrays of plasmonic metal/semiconductor hemispherical nano-heterostructures (MSHNs) with control over spacing and size of the metal/semiconductor heterostructure array, which can facilitate a wide range of scientific studies and applications. The strategy combines nanosphere lithography for generating the metal core array with solution-based chemical methods for the semiconductor shell that are widely available and kinetically controllable. Periodic arrays of Au/Cu₂O and Ag/Cu₂O heterostructures are synthesized to demonstrate the approach and highlight the versatility and importance of the tunability of plasmonic properties. The morphology, structure, optical properties, and elemental compositions of the heterostructures were analyzed. This strategy can be important for understanding and manipulating fundamental nanoscale solid-state physical and chemical properties, as well as assembling heterostructures with desirable structure and functionality for applications.