With large surface-to-volume ratios and Debye length comparable to their small sizes, one-dimensional inorganic nanostructures have extensively been investigated and widely used to fabricate high-performance nanoscale electronic and optoelectronic devices This feature article reviews the state-of-the-art research activities that focus on the one-dimensional inorganic nanostructures and their photodetector applications It begins with a survey of one-dimensional inorganic nanostructures and the fundamentals of photodetectors Some remarkable photoresponse characteristics are then presented, which are organized into sections covering several kinds of important nanostructures, such as ZnO, V 2 O 5 , ZnS, In 2 Se 3 , InSe, CdS, CdSe, ZnSe, Sb 2 Se 3 , ZrS 2 , Ag 2 S, and Zn x Cd 1-x Se Each section describes the corresponding photodetective properties in detail Finally, the article concludes with some perspectives and outlook on the future developments in the field

Recent Developments in One-Dimensional Inorganic Nanostructures for Photodetectors

Multi metal oxide NiO-CdO-ZnO nanocomposite–synthesis, structural, optical, electrical properties and enhanced sunlight driven photocatalytic activity

Zinc oxide (ZnO), with the unique chemical and physical properties of high chemical stability, broad radiation absorption range, high electrochemical coupling coefficient, and high photo-stability, is an attractive multifunctional material which has promoted great interest in many fields. What is more, its properties can be tuned by controllable synthesized morphologies. Therefore, after the success of the abundant morphology controllable synthesis, both the morphology-dependent ZnO properties and their related applications have been extensively investigated. This review concentrates on the properties of morphology-dependent ZnO and their applications in catalysis, mainly involved reactions on green energy and environmental issues, such as CO2 hydrogenation to fuels, methanol steam reforming to generate H2, bio-diesel production, pollutant photo-degradation, etc. The impressive catalytic properties of ZnO are associated with morphology tuned specific microstructures, defects or abilities of electron transportation, etc. The main morphology-dependent promotion mechanisms are discussed and summarized.

https://www.mdpi.com/2073-4344/6/12/188/pdf

The Applications of Morphology Controlled ZnO in Catalysis

A new synergetic hybrid Ag/ZnO nanostructure was fabricated which is able to cause photocatalytic degradation (in high yields) of methylene blue under visible light as well as in the dark. In this nanostructure, ZnO was synthesized using the arc discharge method in water and was coupled with Ag via a chemical reduction method. X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy results confirmed the existence of defects in ZnO in the hybrid nanostructures; these defects act as electron traps and inhibit the recombination of electron-hole pairs. The absorption edge of the hybrid nanostructure shifts toward the visible region of the spectrum due to a combination of the Ag plasmonic effect and the defects in ZnO. Band-edge tuning causes effective visible light absorption and enhances the dye degradation efficiency of Ag/ZnO nanostructures. Silver oxidation in the hetero-structure changed the metal-semiconductor interface and suppressed the plasmonic enhancement. Nevertheless, the synthesized Ag/ZnO decomposed methylene blue in visible light, and the silver oxidation only affected the catalytic activity in the dark. This work provides insight into the design of a new and durable plasmonic-metal oxide nanocomposite with efficient dye degradation even without light illumination.

The effect of silver oxidation on the photocatalytic activity of Ag/ZnO hybrid plasmonic/metal-oxide nanostructures under visible light and in the dark.

Synthesis of novel heterostructured ZnO-CdO-CuO nanocomposite: Characterization and enhanced sunlight driven photocatalytic activity

This study demonstrates significant visible light photo-detection capability of pristine ZnO nanostructure thin films possessing substantially high percentage of oxygen vacancies [Formula: see text] and zinc interstitials [Formula: see text], introduced by simple tuning of economical solution method. The demonstrated visible light photo-detection capability, in addition to the inherent UV light detection ability of ZnO, shows great dependency of [Formula: see text] and [Formula: see text] with the nanostructure morphology. The dependency was evaluated by analyzing the presence/percentage of [Formula: see text] and [Formula: see text] using photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) measurements. Morphologies of ZnO viz. nanoparticles (NPs), nanosheets (NSs) and nanoflowers (NFs), as a result of tuning of synthesis method contended different concentrations of defects, demonstrated different photo-detection capabilities in the form of a thin film photodetector. The photo-detection capability was investigated under different light excitations (UV; 380~420 nm, white ; λ > 420 nm and green; 490~570 nm). The as fabricated NSs photodetector possessing comparatively intermediate percentage of [Formula: see text] ~ 47.7% and [Formula: see text] ~ 13.8% exhibited superior performance than that of NPs and NFs photodetectors, and ever reported photodetectors fabricated by using pristine ZnO nanostructures in thin film architecture. The adopted low cost and simplest approach makes the pristine ZnO-NSs applicable for wide-wavelength applications in optoelectronic devices.

/pdf/visible-and-uv-photo-detection-in-zno-nanostructured-thin-m9sgjsgafu.pdf

Visible and UV photo-detection in ZnO nanostructured thin films via simple tuning of solution method

A simple soft chemical method has been suggested for large-scale production of zinc oxide (ZnO) nanosheets at room temperature using two synthesis mediums: aqueous (H2O) and non-aqueous (C2H5OH). In H2O medium, nanosheets interwoven group wise in flower-like structures revealing the strong inter-hydrogen bonding among initially nucleated ZnO nanocrystals, whereas weak hydrogen bonding in C2H5OH medium leads to the formation of un-aggregated interwoven’ nanosheets. The growth of ZnO flower-like and interwoven nanosheets proceeded via anisotropic oriented attachment of ZnO nanocrystals. Obtained nanosheets were faceted, possessing large surface area, width hundreds of nanometers, and thickness in tens of nanometer, as characterized by scanning electron microscopy and transmission electron microscopy. These nanosheets show high sunlight photocatalytic activity toward the degradation of an organic pollutant ‘methylene blue dye.’ The enhancement in photodegradation efficiencies, interwoven sheets 99.94 %, and flower-like nanosheets 79.76 % for 120 min of irradiation is attributed to the surface oxygen vacancies narrowing the band gap as confirmed by photoluminescence spectra, faceted geometry, and large surface area of ZnO nanosheets.

Effect of synthesis medium on aggregation tendencies of ZnO nanosheets and their superior photocatalytic performance

Nanosheets, nanoparticles, and microstructures of ZnO were synthesized via a wet chemical method. ZnO films with a thickness of 44?46??m were fabricated by spray coating, and these have been investigated for their potential use in turbid lens applications. A morphology-dependent comparative study of the transmittance of ZnO turbid films was conducted. Furthermore, these ZnO turbid films were used to enhance the numerical aperture (NA) of a Nikon objective lens. The variation in NA with different morphologies was explained using size-dependent scattering by the fabricated films. A maximum NA of around 1.971 of the objective lens with a turbid film of ZnO nanosheets was achieved.

/pdf/enhancing-the-numerical-aperture-of-lenses-using-zno-5c67qdgdxj.pdf

Enhancing the numerical aperture of lenses using ZnO nanostructure-based turbid media

A facile room temperature, aqueous solution-based chemical method has been adopted for large-scale synthesis of Fe doped ZnO nanosheets. The XRD and SEM results reveal the as-synthesized products well crystalline and accumulated by large amount of interweave nanosheets, respectively. Energy dispersive spectroscopy data confirmed Fe doping of the ZnO nanosheets with a varying Fe concentration. The photoluminescence spectrum reveals a continuous suppression of defect related emissions intensity by increasing the concentration of the Fe ion. A photocatalytic activity using these samples under sunlight irradiation in the mineralization of methylene blue dye was investigated. The photocatalytic activity of Fe doped ZnO nanosheets depends upon the presence of surface oxygen vacancies.

Effect of Fe doping concentration on photocatalytic activity of ZnO nanosheets under natural sunlight

The ZnO nanoflowers, nanosheets and nanoparticles were synthesized on silicon (Si) wafers by a wet chemical method at low temperature (~ 35oC). The ZnO nanosheets and flowers have been grown without any catalyst and surfactant at low temperature just by solvent variation in the solution. While using the surfactant nanoparticles have been synthesized. The ZnO nanosheet with thickness 10 nm, were interwoven into network to form a nanosheet film on surface of Si substrate. The growth mechanism and an effect of surfactant on the morphology are also discussed in detail.

/pdf/synthesis-of-zno-nanostructures-on-silicon-wafer-by-wet-1prj4c4b6x.pdf

Richa Khokhra

Papers

Visible and UV photo-detection in ZnO nanostructured thin films via simple tuning of solution method

Effect of synthesis medium on aggregation tendencies of ZnO nanosheets and their superior photocatalytic performance

Enhancing the numerical aperture of lenses using ZnO nanostructure-based turbid media

Effect of Fe doping concentration on photocatalytic activity of ZnO nanosheets under natural sunlight

Synthesis of ZnO Nanostructures on Silicon Wafer by Wet Chemical Method