Thermal Annealing Induced Controllable Porosity and Photoactive Performance of 2D ZnO Sheets

Porous ZnO sheets containing various degrees of a nanoscaled pore were successfully synthesized using a simple hydrothermal method and various postannealing procedures. The porosity features of the ZnO sheets can be easily tuned by changing both the annealing temperature and annealing atmosphere. The dense porous nature of ZnO sheets is beneficial to enhance light absorption. Moreover, the substantially increased oxygen vacancies in the ZnO sheets were observed especially after the hydrogen treatment as revealed in the X-ray photoelectron spectroscope and photoluminescence analyses. The high density of surface crystal defect enhanced the photoinduced electron-hole separation rate of the ZnO sheets, which is crucial for an improved photoactivity. The porous ZnO sheets formed at a hydrogen atmosphere exhibited superior photoactive performance than the porous ZnO sheets formed at the high-temperature ambient air annealing. The dense pores and massive crystal defects formed by a hydrogen atmosphere annealing in the ZnO crystals might account for the observed photoactive behaviors in this study.

The effect of Ni content on gas-sensing behaviors of ZnO–NiO p–n composite thin films grown through radio-frequency cosputtering of ceramic ZnO and NiO targets

In this study, dual phase ZnO–NiO p–n composite thin films were grown through radio-frequency cosputtering of ceramic ZnO and NiO targets.

Carbon Dioxide Photoreduction on the Bi2S3/MoS2 Catalyst

The photocatalytic activity of a material is contingent on efficient light absorption, fast electron excitation, and control of the recombination rate by effective charge separation. Inorganic materials manufactured in unique shapes via controlled synthesis can exhibit significantly improved properties. Here, n-type Bi2S3 nanorods (with good optical activity) were wrapped with two-dimensional (2D) p-type MoS2 sheets, which have good light absorption properties. The designed p-n junction Bi2S3/MoS2 composite exhibited enhanced light absorption over the entire wavelength range, and higher carbon dioxide adsorption capacity and photocurrent density compared to the single catalysts. Consequently, the activity of the 1Bi2S3/1MoS2 composite catalyst for the photocatalytic reduction of carbon dioxide was more than 20 times higher than that of the single catalysts under visible-light irradiation at ≤400 nm, with partial selectivity for CO conversion. This is attributed to the p-n heterojunction Bi2S3/MoS2 composite designed in this study, the high light absorption of n-Bi2S3, accelerated electron excitation, and the electron affinity of the 2D sheet-p-MoS2, which quickly absorbed excited electrons, resulting in effective charge separation. This ultimately improved the catalytic performance by continuously supplying catalytically active sites to the heterojunction interfaces.

Chemically Synthesized Hierarchical Flower like ZnO Microstructures

In the present study, we have deposited hierarchical flower-like microstructured zinc oxide (ZnO) thin films directly on a glass substrate by using the simplistic aqueous chemical route for different concentrations of triethanolamine (TEA) which acted like a complexing agent. The as-synthesized ZnO thin films were subsequently annealed at 300 °C and are characterized with characterization techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL), and electrical resistivity. The hexagonal wurtzite crystal structure of as-synthesized ZnO thin films was confirmed by their XRD patterns and the well-resolved ZnO flowers-like morphology was revealed from the FESEM micrographs. From FESEM images it can be seen that the ZnO flower is composed of dozens of nanorods originating from the same core in a symmetric fashion with an average diameter of around 180-300 nm. The flower-like morphology was obtained at 0.3 M TEA concentration. Due to its hierarchical structure, the deposited ZnO thin films were employed for multiple applications such as gas sensing and anti-microbial activity. The ZnO thin films with micro-flowers like morphology showed the maximum gas sensor sensitivity ∼64.50 at 150 °C for 100 ppm of NO2 gas. Moreover, the bacteria were completely destroyed in the presence of as-deposited ZnO thin films.

Enhancing performance of Ag–ZnO–Ag UV photodetector by piezo-phototronic effect

In this work, an ultraviolet (UV) photodetector based on a ZnO nanowires (NWs) array with metal–semiconductor–metal Schottky junction structure was successfully fabricated on a flexible polyester fibre substrate by a low-temperature hydrothermal method. Subjected to a 0.2% tensile strain at −1 V, the I_light and sensitivity of the as-prepared UV photodetector are lifted by 82% and 130%, respectively. Furthermore, the response speed and recovery speed are significantly raised under the same tensile strain. The working principle can be explained as that the Schottky barrier height (SBH) is effectively improved by the negative strain-induced polarization at the metal–ZnO interface which is favorable for the separation of photogenerated electron–hole pairs. This work not only provides a facile and promising means to optimize the performance of a ZnO based MSM photodetector by applying a tensile strain but also opens up the way for fabrication and integration of ZnO photodetectors on flexible polyester fiber substrates.

An ultraviolet photodetector based on a ZnO nanowires with metal–semiconductor–metal Schottky structure was fabricated on a flexible polyester fibre substrate.

One-pot synthesis of lightly doped Zn1-x Cu x O and Au-Zn1-x Cu x O with solar light photocatalytic activity in liquid phase

We report on the facile and low-temperature one-pot chemical synthesis of lightly doped Zn_1-x Cu _x O and hybrid Au-Zn_1-x Cu _x O photocatalysts with low Cu molar content (0 < x < 0.7%) using 1,3-propanediol polyol simultaneously as solvent, reducing and a stabilizing agent, without any final thermal treatment. The photocatalysts have been characterized by X-ray diffraction, N₂ adsorption study, UV-vis diffuse reflectance spectroscopy, inductively coupled plasma optical emission spectroscopy, and transmission electron microscopy. The lightly doped hybrid Au-Zn_1-x Cu _x O photocatalysts consisted in faceted quasi-spherical large-size Au nanoparticle cores surrounded by closely packed small-size Zn_1-x Cu _x O nanoparticles. Taking the photocatalytic degradation of Diuron under solar light as liquid-phase test reaction, the lightly doped Au-Zn_1-x Cu _x O hybrid photocatalysts with optimized x = 0.09% Cu content showed strongly enhanced photocatalytic activity when compared to the bare ZnO counterpart. The observed 16-fold higher degradation rate constant resulted jointly from the light doping of ZnO with Cu to form Zn_1-x Cu _x O photocatalyst and further from the addition of gold nanoparticles allowing interfacial oxide-to-metal electron transfer within the hybrid Au-Zn_1-x Cu _x O photocatalyst.

Enhancing performance of ZnO/NiO UV photodetector by piezo-phototronic effect

The performance of the ZnO/NiO UV photodetector is enhanced by piezo-phototronic effect.

Farming of maize-like zinc oxide via a modified SILAR technique as a selective and sensitive nitrogen dioxide gas sensor

Novel hierarchical nanostructures of metal oxides synthesized via simplistic SILAR cycles.

Morphology controlled synthesis of Al doped ZnO nanosheets on Al alloy substrate by low-temperature solution growth method

We report the morphology-controlled synthesis of aluminium (Al) doped zinc oxide (ZnO) nanosheets on Al alloy (AA-6061) substrate by a low-temperature-solution growth method without using any external seed layer and doping process.

Synthesis and characterization of flower-like NiCoP/ZnO composites

ZnO nanosheets were successfully coated on the surface of a NiCoP microstructure via a solvothermal route.

Zinc oxide based photocatalysis: tailoring surface-bulk structure and related interfacial charge carrier dynamics for better environmental applications

Surface-bulk modification of zinc oxide for efficient photocatalysis.

Additive-free 1,4-butanediol mediated synthesis: a suitable route to obtain nanostructured, mesoporous spherical zinc oxide materials with multifunctional properties

A family of mesoporous, self-aggregated zinc oxide materials with spherical morphologies of high crystalline quality, is obtained through a facile, additive-free polyol procedure.

Dynamically controlled synthesis of different ZnO nanostructures by a surfactant-free hydrothermal method

To broaden the device applications of ZnO nanomaterials, various ZnO nanostructures have been fabricated by physical disturbance assisted hydrothermal method.