ZnO Nanorod Arrays Research Articles

High-Performance Inverted Structure Broadband Photodetector Based on ZnO Nanorods/PCDTBT:PCBM:PbS QDs

This article reports the performance improvement of a broadband photodetector using penetrating ZnO nanorods arrays (NRAs)-based electron transport layer (ETL) into a nanocomposite active layer of poly-[N-9''-heptadecanyl-2.7-carbazole-alt-5.5(4',7'-di-2-thienyl-2',1',3 -benzothiadiazole)] (PCDTBT), [6,6]-phenyl C61 butyric acid methyl ester (PCBM), and PbS quantum dots (QDs) grown on an fluorine-doped tin oxide (FTO)-coated glass substrate. A thin layer of MoOx on the active layer was used as the hole transport layer (HTL) of the proposed photodetector. The device showed a high responsivity of ~213.77, ~28.57, and ~7.22 A/W at three selected wavelengths in ultraviolet (380 nm), visible (550 nm), and near-infrared (860 nm) regions, respectively. High external quantum efficiency (EQE) of more than 1000% was measured for each selected wavelength at low -1.5 V external bias. The superior EQE in the proposed device was attributed to both the surface trap-induced carrier injection into the ZnO NRA and ultrafast exciton dissociation existing in the PCDTBT:PCBM system.

Catalytic Activation of Cobalt Doping Sites in ZIF-71-Coated ZnO Nanorod Arrays for Enhancing Gas-Sensing Performance to Acetone.

Developing acetone gas sensors with high sensitivity is crucially important for many applications including nonevasive diagnosis of diabetes. In the present work, cobalt doping is used to catalyze acetone gas-sensing reactions and hence to promote the sensitivity of acetone gas sensors. In order to achieve this, ZIF-71 metal-organic framework (MOF) is synthesized onto ZnO nanorod arrays with various concentrations of Co doping to form composite ZnO@ZIF-71(Co) sensors, which are then evaluated as sensing materials for acetone detection. Such sensors are shown to be sensitive to a trace amount of acetone (50 ppb) and have a massively enhanced response of about 100 times that for the undoped sensor at an optimal Co/Zn ratio and operating temperature. Fourier-transform infrared spectroscopy and temperature-programmed desorption with density functional theory calculations are also made to assist in elucidating the catalytic gas-sensing mechanism for the Co-doped composite sensors ZnO@ZIF-71(Co). It demonstrated that the introduced Co site in ZIF-71(Co) can activate oxygen catalytically and increase active oxygen released to the ZnO surface. Meanwhile, the Co sites also promote the decomposition of acetone. These two steps together affect the catalytic oxidation of gases and finally enhance the sensitivity. This work introduces the catalytic effect of the MOF into the gas-sensing mechanism and provides an idea for broadening the application of MOF catalysis.

Flexible, polymer-supported, ZnO nanorod array photoelectrodes for PEC water splitting applications

An innovative ZnO based flexible photoelectrode was prepared on the micropatterned poly (urethane acrylate) (PUA) for efficient photoelectrochemical water splitting application. The micropatterned PUA was fabricated by the mold transfer process. A thin layer of Indium Tin Oxide was deposited on the PUA surface to give it surface conductivity and subsequently, one dimensional ZnO nanorods (NRs) arrays were prepared by a facile seed layer and hydrothermal method. The photocurrent density of the photoanode of ZnO NRs arrays deposited on the micropatterned PUA (ZPM) was ~0.52 mA cm−2 at 1.23 V vs. RHE, which was ~3 times higher compared to that of ZnO NRs arrays deposited on the flat PUA (ZPF). The improved performance of the ZPM photoanode was attributed to the enhanced light capture capacity, excellent carrier collection ability, lower charge transfer resistance, and higher electrochemically active surface area.

Charge transfer plasmon coupled surface photosensing in ZnO nanorods–Au array hetero-nanostructures

Well-aligned zinc oxide nanorods (ZnO NRs) array have been grown by wet chemical method on seeded substrates at low temperature. Gold nanosheet has been deposited by DC magnetron sputtering on the surrounding of the ZnO NRs array at glancing angle, thus creating a three-dimensionally (3D) plasmonic hetero-nanostructure (HNS). The localized surface plasmon resonance (LSPR) is tuned and blue-shifted as the thickness of the gold nanosheet increased. The efficient surface plasmon (SP) excitation, and charge transfer plasmon through tunneling transport and junction conductance elevates the locally electromagnetic field and subsequently enhances surface Raman scattering in ZnO NRs-Au array HNS. An enhanced factor (EF) of 500 can be obtained for the surface enhancement Raman scattering (SERS) response for ZnO NRs-Au array HNS. Photoluminescence spectrum shows Au- mediated blue emission enhancement. The ZnO NRs–Au HNSs show high nonlinear refractive index and nonlinear optical absorption coefficient around 10−5 cm2/W and 1 cm/W, respectively. The ZnO NRs-Au array HNS can provide the figures of merit w = 209.83 and t = 0.59 for the optical switching devices. Photosensitivity and photocatalytic activity are elevated in ZnO NRs-Au array HNS. The ZnO NRs-Au array HNS shows maximal photocurrent enhancement of 69.38% in comparison to the bare ZnO NRs array.

Graphene quantum dots-wrapped vertically aligned zinc oxide nanorods arrays for photosensing application

Herein, we report an innovative and facile approach to prepare graphene quantum dot (GQD)-wrapped vertically aligned zinc oxide (ZnO) nanorod (NR) arrays. The ZnO NR/GQD heterostructure was prepared as a core/shell structure on an indium tin oxide (ITO) substrate using spin-coating, electron-beam evaporation, and a rapid thermal process combined in a novel way. Spin-coated poly(methyl methacrylate) (PMMA) was converted to GQDs on ZnO NRs by high temperature thermal treatment. A metal-capping layer was used to convert PMMA into GOD by avoiding the thermal evaporation of PMMA. Two different metals Ni and In were used as capping layers and studied their effect in the thermal conversion of PMMA into GQDs and in the properties of the fabricated devices. Structural, morphological, compositional and optical properties of the as-prepared ZnO NR/GQD heterostructures were characterized. The devices consisting of 50–70 nm ZnO NRs covered with GQDs as a core-shell structure demonstrated efficient UV photosensing with excellent photoresponse due to the GQDs showing high carrier transport and photoabsorption. The fabricated ITO/ZnO NR/GQD/In device showed better photosensing responsivity than the ITO/ZnO NR/GQD/Ni one. This is an entirely new technique for growing GQDs directly on previously prepared ZnO NRs.

Earth abundant transition metal ferrite nanoparticles anchored ZnO nanorods as efficient and stable photoanodes for solar water splitting

Poor light absorption, severe surface charge recombination and fast degradation are the key challenges with ZnO nanostructures based electrodes for photoelectrochemical (PEC) water splitting. Here, this study attempts to design an efficient and durable nano-heterojunction photoelectrode by integrating earth abundant chemically stable transition metal spinel ferrites MFe2O4 (M = Co and Ni) nano-particles on ZnO Nanorod arrays. The low band gap magnetic ferrites improve the solar energy harvesting ability of the nano-heterojunction electrodes in ultraviolet–visible light region resulting in a maximum increase of 105% and 190% in photocurrent density and applied bias photon-to-current efficiency, respectively, compared to pristine ZnO nanorods. The favourable type-II band alignment at the ferrites/ZnO nano-heterojunction provides significantly enhanced photo-generated carrier separation and transfer, endowing the excellent solar H2 evolution ability (743 and 891 μmol cm−2 h−1for ZnO/CoFe2O4 and ZnO/NiFe2O4, respectively) of the photoanodes by using sacrificial agent. The hybrid nanostructures deliver long term stability of the electrode against photocorrosion. This work demonstrates an easy but effective strategy to develop low-cost earth abundant ferrites-based heterojunction electrodes, which offers excellent PEC activity and stability.

Bi2S3 anchored ZnS/ZnO nanorod arrays photoanode for enhanced visible light driven photo electrochemical properties

We report on the enhanced photoelectrochemical water splitting of hybrid ZnS/ZnO core-shell nanorod arrays functionalized with Bi2S3 nanosheets as photoanode. The ZnO nanorod arrays were prepared by a facile hydrothermal approach and sulphurized to form ZnS shell. Subsequently porous Bi2S3 nanosheets were arbitrarily decorated on the nanorod arrays by ionic adsorption and reaction method. Substantial enhancement in photocurrents with twofold increment is observed for hybrid photoanode compared to pristine counterparts. The structural and morphological properties of nano hybrid Bi2S3/ZnS/ZnO samples were analyzed by field emission scanning electron microscopy and X-ray diffraction. The higher wavelength shift in the absorption edge of Bi2S3/ZnS/ZnO photocatalyst was observed in diffuse reflectance UV–Visible spectra. The low temperature photoluminescence and impedance spectra of Bi2S3/ZnS/ZnO photoanode confirm that Bi2S3 functionalization reduces the recombination of electron–hole pair and facilitates barrier free charge transfer. The Bi2S3/ZnS/ZnO photoanode device exhibits photocurrent density of 220 μA/cm2 at 0.2 V vs. Ag/AgCl under the electrolyte solution at pH ~10.8. The resultant hybrid photoanode withhold good stability and maintain the facile charge carrier generation and separation. Bi2S3 topological nanosheets are responsible for the absorption of complete visible photons while ZnS/Bi2S3 inter-junction provides the robust electron-hole pair separation at their interface due to infiltration pathway. The photoactive hybridization of Bi2S3/ZnS/ZnO provokes the enhanced donor charge density for efficient hydrogen evolution reaction.

Competitive effect of dopant concentration and the size of the nanorods over the electron phonon coupling in Cd doped ZnO nanorod arrays

Earlier reports on resonance Raman scattering in ZnO suggests that the electron phonon coupling in ZnO usually increase with nanoparticle size or decline with the doping concentration. We investigated the effect of combination of the concentration of dopant and the variation of size of nanorods over the electron phonon interaction in Cd doped ZnO nanorod array fabricated by a simple, low temperature (90 °C) growth process. The resonant Raman measurement revealed minor decrease in the electron phonon coupling strength as defined by the intensity ratio (I2LO/I1LO) at low doping concentration (20 mol %) and increase at high Cd concentration (>20 mol %) confirming a strong dependence of electron phonon coupling strength on the concentration of dopant. The enhancement in the electron phonon coupling strength at high doping concentration was due to the increase in the diameter of the nanorod rather than the concentration of dopants explaining the competitive effect of dopant and size over the electron phonon interaction in a range of doping concentration. The Cd doping led to the decrease in the band gap and the increase (decrease) in the intensity of the excitonic emission (visible luminescence) as observed by the photoluminescence property. X-ray, Fourier transform infrared (FTIR) analysis confirmed low temperature doping of Cd at the tetrahedral coordination site of the ZnO lattice Although, the Cd concentration in the growth solution was systematically varied from 1 mol % to 80 mol %, the maximum Cd doping varied from 3 at. % (80 mol %) at the surface to 0.2 at % - 0.6 at. % in the bulk after surface cleaning by Ar ion etching.

Fabrication and characterization of Cu2S/ZnO nanorods photoelectrode for photoelectrochemical cell

In this study, Cu2S/ZnO nanorods arrays (NRAs) nanocomposite have been efficiently papered via dual methods: firstly, ZnO NRAs by a hydrothermal method, and secondly Cu2S nanoparticles via successive ionic layer adsorption (SILAR). Cu2S/ZnO photoelectrode is collected from ZnO which is presented as a fast electron transportation way because of its high mobility and Cu2S as good sensitized material due to its small energy gap. XRD analysis, FESEM images, EDX analysis, UV–Vis spectra and photoelectrochemical performance (PEC) of bra ZnO and Cu2S/ZnO were characterized. All characterizations have confirmed formed the Cu2S/ZnO NRAs nanocomposite. PEC measurement was strong evidence to synthesis of Cu2S/ZnO which exhibited the anodic photocurrent density of pure ZnO NRs (0.12 mA cm−2) that was lower than Cu2S/ZnO NRAs (0.93 mA cm−2) at 1.0 V vs. Ag/AgCl.

High-performance ordered porous Polypyrrole/ZnO films with improved specific capacitance for supercapacitors

Ordered porous polypyrrole/ZnO (PPy/ZnO) nanocomposites were synthesized on a fluorine tin oxide (FTO) substrate using an independent ZnO nanorod array template-assisted electrodeposition and template removal process with a pore size between 100 nm and 200 nm. The ordered porous structure of PPy/ZnO was verified by scanning electronmicroscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FTIR). The specific capacitance of porous PPy/ZnO nanocomposites can be as high as 161.02 F g−1, which is far higher than pure PPy (100.17 F g−1) at 1 M KCl aqueous solution with a current density of 0.5 A g−1. The improvement of specific capacitance performance is not only ascribe to the exposure of more active sites to obtain larger specific surface area, but also because of the synergistic effect between conductive PPy and ZnO, which shorten the electron transport channel, enhance the transmission efficiency of electrons in the entire electrode, and consequently result in a faster electron transfer. The specific capacitance of the porous PPy/ZnO nanocomposites retains 70.71% after 5000 cycles of charge/discharge, exhibiting good electrochemical cycle stability, which provides a potential as high-performing electrode material in supercapacitors.

High efficient Al: ZnO based bifocus metalens in visible spectrum**Project supported by the National Key Research and Development Program of China (Grant No. 2017YFB0403101).

The optical components of the visible light band are widely used in daily life and industrial development. However due to the serious loss of light and the high cost, the application is limited. The broadband gap metasurface will change this situation due to its low absorption and high efficiency. Herein, we simulate a size-adjustable metasurface of the Al doped ZnO (AZO) nanorod arrays based on finite difference time domain method (FDTD) which can realize the conversion of amplitude polarization and phase in the full visible band. The corresponding theoretical polarization conversion efficiency can reach as high as 91.48% (450 nm), 95.27% (530 nm), and 91.01% (65 nm). The modulation of focusing wavelength can be realized by directly adjusting the height of the AZO nanorod. The designed half-wave plate and metalens can be applied in the imaging power modulation halfwave conversion and enriching the spectroscopy.

Visible light driven photosplitting of water using one dimensional Mg doped ZnO nanorod arrays

In the present work, we have introduced Mg doped ZnO nanorods based photoanodes for photoelectrochemical water splitting applications. Vertically aligned Mg doped ZnO nanorods were fabricated by sol-gel and hydrothermal technique. The as-prepared nanorod samples exhibited hexagonal wurtzite structure as confirmed from XRD measurements. We achieved a photocurrent density of 0.35 mA/cm2 at 1.5 V vs. Ag/AgCl for 10% Mg doped ZnO photoanode which is 9 times higher than that of undoped ZnO nanorods (0.03 mA/cm2). Incorporation of Mg resulted in faster charge transport and longer life time of electrons with reduced recombination rate. Mg dopant tuned the optical band gap of ZnO and increased the carrier concentration boosting the PEC performance of the photoanodes. Since seawater is one of the most abundant natural resource on earth, we further carried out seawater splitting of 10MgZ under visible light illumination which indicated its high photostability in natural seawater for 5 h of continuous illumination.

ZnO nanorod arrays assembled on activated carbon fibers for photocatalytic degradation: Characteristics and synergistic effects

Well-aligned ZnO nanorod arrays were assembled on activated carbon fibers by a stepwise sequence of sol-gel and hydrothermal synthesis methods. These ZnO nanorod arrays on activated carbon fibers having different characteristics such as surface area, rod concentration, aspect ratio and defect level, were applied as catalysts for the photodegradation of an aqueous methylene blue solution. They showed very promising methylene blue adsorbility in the dark (ca. 0.025–0.031 mg methylene blue m−2 catalyst, vs. 0.072 mg methylene blue m−2 activated carbon fibers). Significantly, the defect level of ZnO nanorod arrays has a major effect on the turnover frequency compared to other characteristics. A synergistic effect between activated carbon fibers and ZnO nanocrystals on enhancing turnover frequency was more significant for the well-assembled ZnO nanorod arrays on activated carbon fibers catalysts compared to the mechanically mixed ZnO powder with activated carbon fibers catalyst. Further, turnover frequency for the ZnO nanorod arrays on activated carbon fibers (0.00312 molmethylene blue molZnO−1 h−1) was twice higher than that for the corresponding bare ZnO nanorod arrays, and 3 times higher than that for a commercial ZnO powder. In addition, ZnO nanorod arrays on activated carbon fibers show high degradation (77.5%) and mineralization (55.0%) levels for methylene blue, and also good reusability (or stability) as demonstrated by a sequential 5-time recycle routine. These outstanding features indicate that activated carbon fibers supported ZnO nanorod arrays have significant potential to be used as catalysts for photodegradation.

Enhanced optoelectronic performance of 3C–SiC/ZnO heterostructure photodetector based on Piezo-phototronic effect

Abstract Piezo-phototronic effect is widely utilized to improve the performance of optoelectronic devices through the coupling of semiconducting, optical, and piezoelectric properties in the ability to adjust charge carrier transport, separation and recombination process in piezoelectric semiconductors. In this paper, we demonstrate the photoresponse enhancement of a 3C–SiC/ZnO heterostructure photodetector based on piezo-phototronic effect. By introducing the strain-induced piezo-potential in ZnO nanorods array radially grown on an individual 3C–SiC nanowire core, photodetector performance is significantly enhanced due to the carrier-dynamics modulation at the local interface. The high photoresponsivity of 1.01 × 106 A/W and fast photoresponse time of 24.1 ms are obtained by applying an external compressive strain of −0.381%, corresponding to the enhancement of 117% in responsivity and shortening to 75.9% in photoresponse time, respectively, showing its outstanding ultraviolet (UV) light detection ability. The possible mechanism of strain-induced piezo-phototronic effect involved in 3C–SiC/ZnO heterostructure photodetector is proposed and discussed. These results present a new avenue for better utilizing piezo-potential in coupling with light, and are valuable for designing and fabricating strain modulated heterostructure optoelectronic devices.

Modeling and Piezoelectric Analysis of Nano Energy Harvesters.

The expedient way for the development of microelectromechanical systems (MEMS) based devices are based on two key steps. First, perform the simulation for the optimization of various parameters by using different simulation tools that lead to cost reduction. Second, develop the devices with accurate fabrication steps using optimized parameters. Here, authors have performed a piezoelectric analysis of an array of zinc oxide (ZnO) nanostructures that have been created on both sides of aluminum sheets. Various quantities like swerve, stress, strain, electric flux, energy distribution, and electric potential have been studied during the piezo analysis. Then actual controlled growth of ZnO nanorods (NRs) arrays was done on both sides of the etched aluminum rod at low-temperature using the chemical bath deposition (CBD) method for the development of a MEMS energy harvester. Micro creaks on the substrate acted as an alternative to the seed layer. The testing was performed by applying ambient range force on the nanostructure. It was found that the voltage range on topside was 0.59 to 0.62 mV, and the bottom side was 0.52 to 0.55 mV. These kinds of devices are useful in low power micro-devices, nanoelectromechanical systems, and smart wearable systems.

Improved photoelectrocatalytic properties of ZnO/CuWO4 heterojunction film for RhB degradation

In this work, we report on the photoelectrocatalytic properties of nanostructured ZnO/CuWO4 heterojunction film prepared by combining the hydrothermal and doctor-blade methods. For ZnO and CuWO4 heterojunction films, X-ray diffraction (XRD) spectra showed the wurtzite and triclinic structure phases, respectively, and no deleterious phases were observed. Scanning electron microscopy (SEM) images showed ZnO nanorods (NRs) grown perpendicular to the substrate and a CuWO4 nanoparticle surface coating on the ZnO/CuWO4 film. The formation of heterojunction film allowed a greater use of visible light and better photoelectrochemical behavior for the ZnO/CuWO4 film. The ZnO, CuWO4, and ZnO/CuWO4 films were used for electrochemically assisted (PEC) RhB photodegradation. The ZnO/CuWO4 film had a PEC photodegradation efficiency of 82 %, making it approximately twice as effective as ZnO film. The incorporation of CuWO4 into the ZnO NR array film with a bias potential remarkably promoted the photogenerated carrier separation and increased the use of photogenerated carriers in photocatalytic reactions, resulting in a higher photocatalytic activity under visible light.

Fabrication of Ultraviolet Photodetectors Based on Fe-Doped ZnO Nanorod Structures.

In this paper, 100 nm-thick zinc oxide (ZnO) films were deposited as a seed layer on Corning glass substrates via a radio frequency (RF) magnetron sputtering technique, and vertical well-aligned Fe-doped ZnO (FZO) nanorod (NR) arrays were then grown on the seed layer-coated substrates via a low-temperature solution method. FZO NR arrays were annealed at 600 °C and characterized by using field emission scanning microscopy (FE-SEM) and X-ray diffraction spectrum (XRD) analysis. FZO NRs grew along the preferred (002) orientation with good crystal quality and hexagonal wurtzite structure. The main ultraviolet (UV) peak of 378 nm exhibited a red-shifted phenomenon with Fe-doping by photoluminescence (PL) emission. Furthermore, FZO photodetectors (PDs) based on metal–semiconductor–metal (MSM) structure were successfully manufactured through a photolithography procedure for UV detection. Results revealed that compared with pure ZnO NRs, FZO NRs exhibited a remarkable photosensitivity for UV PD applications and a fast rise/decay time. The sensitivities of prepared pure ZnO and FZO PDs were 43.1, and 471.1 for a 3 V applied bias and 380 nm UV illumination, respectively.

Structural, electrochemical and optical properties of Ni doped ZnO: Experimental and theoretical investigation

Pure and Ni-doped ZnO nanorod array films were prepared by the hydrothermal method. The effects of Ni doping on the phase composition, microstructure, and optical and electro-chemical properties of ZnO were investigated. The main crystalline phase of the powders before and after Ni doping is wurtzite ZnO. The luminescent peaks are significantly reduced after Ni doping. The light transmission and is the strongest when the doping concentration is 2 %. The light absorption spectrum confirms that the band gap decreased first and then decreased with the increase of Ni2+ doping concentration. According to the M–S (Mott - Schottky) plots, the Ni-doped ZnO is an n-type semiconductor. The current density initially increases with the increased Ni doping amount, and then decreases. First-principles calculation results of nickel-doped zinc oxide show that the energy level of impurities is formed after nickel ions replace zinc ions, which causes the conduction band is shifted down and the band gap is reduced. The impurity energy level causes a slight upward shift in the valence band, which increases the band gap. The calculated results are consistent with the experimental results.

Silver nanoparticles coupled ZnO nanorods array prepared using photo-reduction method for localized surface plasmonic effect study

Coupling of selected metal nanoparticles (NPs) on the surface of ZnO nanorods (NRs) array grown on conductive glass substrates is one of the approaches to tailor the optical properties of ZnO NRs. It is a metal oxide deposition process followed by an annealing treatment to convert the deposits to metal NPs. However, the conductive glass substrates could easily deform during this annealing process. This issue limits the application of ZnO NRs array that grown on glass substrates for the fabrication of ZnO based devices. Thus, the development of metal NPs deposition technique without the need of post-deposition annealing is highly desired. This work demonstrated a successful and controlled deposition of silver (Ag) NPs on ZnO NRs array grown on fluorine doped tin oxide (FTO) glass substrates without any post-deposition annealing and, the product has exhibited localized surface plasmonic resonance (LSPR) phenomenon. The ZnO NRs arrays were grown on FTO glass substrates that pre-seeded with ZnO layer using hydrothermal method. The controlled coupling of Ag NPs particles on ZnO NRs was performed by adjusting the duration of photo-reduction process. The optical bandgap ZnO NRs was widened because of Ag NPs coupling, i.e. from 3.16 to 3.22 eV; as estimated from the result of UV–Vis measurement. The shift of near band-edge emission (NBE) in room temperature photoluminescence (RTPL) suggests that the presence of Ag NPs on the surface of ZnO NRs could block the transitions of electrons in ZnO whereas the shift in defect-related emission indicates the generation of defects at the interfaces between Ag NPs and ZnO NRs. The 5-folds increment of IUV/Vis ratio of Ag NPs/ZnO NRs in RTPL, indicating the specimens experienced LSPR effect. The LSPR effect of Ag NPs/ZnO NRs could be used to improve the performance of ZnO-based devices such as solar cells, light-emitting diodes and photocatalysts applications.

Vertically aligned ZnO nanorods for photoelectrochemical water splitting application

In this present study, nucleation controlled vertically oriented Zinc Oxide nanorod (ZNR) array based Photoanodes was successfully synthesized on conductive substrate by hydrothermal method for Photoelectrochemical (PEC) cell. We have investigated the effect of ammonia during the synthesis on morphology of ZNR and its effect on current–voltage characteristics of PEC cell. Synthesized ZNR were subjected to X-ray diffraction (XRD), UV–Visible spectroscopy, Field emission scanning electron microscopy (FE-SEM), Energy dispersion spectroscopy (EDX) for microstructural characterization. Presence of single (002) peak in XRD pattern confirms vertical c-axis oriented growth of ZnO rods. FE-SEM images revealed that concentration of ammonia had marked effect on crystallization, morphology and density of ZnO rods. PEC properties were investigated by using ZnO rods as photoanode in three electrode cells under AM 1.5G illumination. Morphology and crystallization of ZnO rods had marked effect on current–voltage characteristics.