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Surface modification and wetting state transformation of ZnO based nanomaterials have been extensively investigated due to their substantial roles in current industrial applications. In this work, we demonstrated the formation of highly crystalline and ordered Bi/ZnO nanorods arrays (Bi/ZNRs) grown on FTO substrate via a feasible hydrothermal method, as a function of reaction time (t). The lateral diameter of the nanostructures were found increased from 23 nm to 43 nm when the reaction time increased from 30 min to 90 min. An in-depth analysis and incisive mechanism of crystal growth under the function of reaction time were proposed. The crystal defect which originated from different Bi incorporation pathways has been declared as the main factor altering the optical energy, electrical properties and band structure of Bi/ZNRs. The Bi/ZNRs showed a higher localize current of 14.5 pA as compared to pristine ZNRs under an 6V applied bias condition, revealing the nature of Bi as a pentavalent dopant that contributed to a density of free electron. Additionally, the Bi/ZNRs also revealed a red shifted in optical energy band gap and exhibit a wetting transition from hydrophobic to hydrophilic textured surface. The novel nanostructures reported herein exhibit interesting physical and optical properties for the fabrication of high performance optoelectronic devices.

Zinc oxide nanorods (ZnO NRs) have gained considerable research interest due to their robust energy conversion efficiency. In the present work, ZnO NRs arrays were pinpointed to probe their electromechanical response under strain conditions. ZnO seed was sputtered on different substrates by radio frequency magnetron sputtering (RF) technique at 80 W constant power and 3.49 × 10−5 mbar base pressure. The X-ray diffraction patterns exhibit hexagonal wurtzite structure with preferred c-axis crystal directions in the (002) plane. The average thickness of the seed layer for all the samples was estimated at around 214.6 nm. Surface roughness and morphologies of the nanorods have been characterized by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), respectively. FE-SEM images show homogeneous growth in different directions on substrates. The average diameters of ZnO NRs on silicon, glass and ITO were 51, 58 and 61 nm, respectively. The average length of all the nanorods on the substrates were measured around 1–2 μm. The local piezoresponse measurements conducted on two selected domain regions of the nanorod arrays had been characterized by piezoresponse force microscopy (PFM) to confirm the switching-piezoelectric behavior.

Zinc oxide (ZnO) nanorods have attracted considerable attention in recent years owing to their piezoelectric properties and potential applications in energy harvesting, sensing, and nanogenerators. Piezoelectric energy harvesting-based nanogenerators have emerged as promising new devices capable of converting mechanical energy into electric energy via nanoscale characterizations such as piezoresponse force microscopy (PFM). This technique was used to study the piezoresponse generated when an electric field was applied to the nanorods using a PFM probe. However, this work focuses on intensive studies that have been reported on the synthesis of ZnO nanostructures with controlled morphologies and their subsequent influence on piezoelectric nanogenerators. It is important to note that the diatomic nature of zinc oxide as a potential solid semiconductor and its electromechanical influence are the two main phenomena that drive the mechanism of any piezoelectric device. The results of our findings confirm that the performance of piezoelectric devices can be significantly improved by controlling the morphology and initial growth conditions of ZnO nanorods, particularly in terms of the magnitude of the piezoelectric coefficient factor (d33). Moreover, from this review, a proposed facile synthesis of ZnO nanorods, suitably produced to improve coupling and switchable polarization in piezoelectric devices, has been reported.

A homogeneous CuO-ZnO nanostructure with tunable morphology and optical band structure is successfully synthesized via a hydrothermal method under the different dopant mole ratios of Cu. The robust correlation between the crystallite size, surface morphology, optical band gap alteration of the synthesized CuO-ZnO and its performance in photoelectrochemical (PEC) activity are investigated and compared to the reference ZnO based photocathode. In this report, it is found that the morphology of hexagonal ZnO nanorod is changed to nanosheet and vertically align CuO-ZnO based nanograss after the Cu incorporation. This result is mainly due to the composition phase change after the excessive incorporation of Cu metal into ZnO lattice. Furthermore, the optical band gap of the sample also presented a bathochromic shifted after the Cu insertion. The measurements on PEC activity of CuO-ZnO nanostructure was performed under the irradiation of a 100 mWcm ^−2 Xenon light in 0.5M Na _2 SO _4 electrolyte. Among the sample, 0 Zn:1 Cu exhibited a highest photocurrent density which is 5 fold as compared to its reference ZnO samples. This finding could be due to the highest surface active area and lowest optical energy band gap in the 0 Zn:1 Cu nanograss that eventually contributes to a high free electron density that facilitates the charge transport in the photoelectrochemical cells. This novel approach could provide an alternative to the future solar hydrogenation application.

Crystallography plane orientation and surface defect on the nanostructure play an important role in optical gas sensor application due to its peculiar quantum properties. In this paper, we report on a formation of highly oriented (002) plane bounded ZnO nanorods ended with a surface defect hexagonal plane, prepared through microwave assisted hydrolysis within 20 s and used as a CO gas detector. A novel photoluminescence-based optical sensor approach was introduced to study the sensor response of the hazardous CO gas as low as 10 ppm at room temperature. The effect of ZnO nanorod arrays prepared by microwave-assisted hydrolysis and hydrothermal was studied towards CO gas response. It was found that the ZnO nanorods prepared through a microwave-assisted hydrolysis approach exhibited remarkable response at 81.1% towards 100 ppm CO gas exposure and showed an ultrafast recovery time of approximately 2.5 min. This provides an excellent sensing approach for operating a low concentration CO gas detection system at room temperature. [ABSTRACT FROM AUTHOR]

This Research Article reports an unusually high efficiency heterogeneous photodegradation of methyl orange (MO) in the presence of Ag nanoparticle-loaded ZnO quasinanotube or nanoreactor (A-ZNRs) nanocatalyst grown on FTO substrate. In typical process, photodegradation efficiency of as high as 21.6% per pg per Watts of used catalyst and UV power can be normally obtained within only a 60-min reaction time from this system, which is 10³ order higher than the reported results. This is equivalent to the turnover frequency of 360 mol mol-1h-1 High-density hexagonal A-ZNRs catalysts were grown directly on FTO substrate via a seed-mediated microwave-assisted hydrolysis growth process utilizing Ag nanoparticle of approximately 3 nm in size as nanoseed and mixture aqueous solution of Zn(NO3)-6H2O, hexamethylenetetramine (HMT), and AgNO3 as the growth solution. A-ZNRs adopts hexagonal cross-section morphology with the inner surface of the reactor characterized by a rough and rugged structure. Transmission electron microscopy imaging shows the Ag nanoparticle grows interstitially in the ZnO nanoreactor structure. The high photocatalytic property of the A-ZNRs is associated with the highly active of inner side's surface of A-ZNRs and the oxidizing effect of Ag nanoparticle. The growth mechanism as well as the mechanism of the enhanced-photocatalytic performance of the A-ZNRs will be discussed. [ABSTRACT FROM AUTHOR]

• ZnO–B 2 O 3 –SLS glass system successfully fabricate using waste soda-lime-silica (SLS) • 3 wt% Sm3+-doped ZnO–B 2 O 3 –SLS glass indicate the most intense emission among other samples. • CIE chromaticity coordinates present the glass sample in an orange-reddish region. • Sm3+-doped in ZnO-B 2 O 3 -SLS potential as an orange-reddish glass phosphor material. In this paper, a series of [Sm 2 O 3 ] x [(ZnO) 0.5 (B 2 O 3) 0.1 (SLS) 0.4 ] 1- x , where × = 0, 0.01, 0.02, and 0.03 in weight fraction was fabricated via melt-quenching method. The influence of the samarium ion (Sm3+) concentration on the structural and optical properties was investigated. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the samples' glassy (amorphous) behavior. The optical absorption intensity enhanced as the dopant increased, whereas the optical band gap reduced with the progression of Sm3+ concentration. The sample's refractive index and Urbach energy range from 2.145 to 2.203 and 0.682 eV to 0.713 eV, respectively. From the photoluminescence studies, 3 wt% Sm3+-doped samples indicate the most intense emission in the orange-reddish region among the other samples. The calculated CIE coordinates for Sm3+ doped ZnO–B 2 O 3 –SLS glasses are approximate (0.57, 0.43), near the Amber LED NSPAR 70BS produced by Nichia Corporation. In addition, the CCT of the Sm3+-doped samples at about ∼ 1750 K reveals prepared glass samples have bright orange-reddish emission. These findings indicate that Sm3+-doped in ZnO-B 2 O 3 -SLS has enhanced its orange-reddish emission and potential as an orange-reddish glass phosphor material in optoelectronic devices such as glass phosphor for LEDs. [ABSTRACT FROM AUTHOR]