Niyom Hongsith - Academia.edu (original) (raw)

Papers by Niyom Hongsith

In this work, the effects of solution on the growth of zinc oxide tetrapod (T-ZnO) were investiga... more In this work, the effects of solution on the growth of zinc oxide tetrapod (T-ZnO) were investigated. T-ZnO nanostructures were prepared by the thermal oxidation technique of metal zinc powder mixed with different solutions such as methanol (CH 3 OH), ethanol (C 2 H 5 OH) and hydrogen per oxide (H 2 O 2 ). The mixtures were heated at the temperature of 1,000 o C in normal atmosphere. A detailed field emission scanning electron microscopy (FE-SEM) showed that T-ZnO prepared by heating zinc and H 2 O 2 gave the best tetrapodlike nanostructures. The length and diameter at the leg tip of T-ZnO is about 8.17 1.17 μm and 47.8 nm, respectively. With this condition the highest percent yield of T-ZnO was about 4.82% by weight. Moreover, as determined by the energy dispersive spectroscopy (EDS), the atomic ratio of Zn and O was about 1:1. In addition, this study reveal that H 2 O 2 acts as a strong oxidizing properties and has a role as a strong oxidizer to supply more reactive oxygen species...

ZnO nanobelts layer of the dye-sensitized solar cell were prepared by RF sputtered ZnO target ont... more ZnO nanobelts layer of the dye-sensitized solar cell were prepared by RF sputtered ZnO target onto a copper substrate and characterized by FE-SEM. The structures of solar cells based on ZnO as a photoelectrode, Eosin-Y as a dye sensitizer, iodine/iodide solution as an electrolyte and Pt/TCO as a counterelectrode. The photoelectrochemical characteristics of ZnO DSSCs were tested under simulated sunlight AM 1.5 came from a solar simulator with the radiant power of 100 mW/cm 2 . It was found that DSSCs based on ZnO nanobelts can generate photocurrent with photoconversion efficiency of 0.6% (J SC = 2.11 mA cm -2 , V OC = 0.52, FF = 0.61).The higher J SC in ZnO nanobelt DSSC sample indicates that larger amount of dye adsorbed on surface of ZnO nanobelts than that of ZnO powder. The J SC increases with increasing a thickness of the ZnO photoelectrode for both powder and nanobelt. Moreover, the V OC of ZnO DSSCs is independent on morphology and dye adsorption surface area of ZnO. The obtai...

In past decades, gas sensors based on the metal oxide semiconductors (MOSs) have been studied in ... more In past decades, gas sensors based on the metal oxide semiconductors (MOSs) have been studied in diverse field for wide applications. A gas sensor is a device that can be used to detect various gas such as ethanol, LPG, CO2 and CO gases etc. The gas sensors based on MOSs such as SnO2, TiO2, WO3, ZnO, Fe2O3, and In2O3 have an important role in environmental monitor‐ ing, chemical process controlling, personal safety (Q. Wan et al., 2004), industrial process controls, for the detection of toxic environmental pollutants in human health, and for the prevention of hazardous gas leaks, which comes from the manufacturing processes (K. Arshak&I. Gaidan, 2005), wine quality monitoring, and traffic safety (X.F. Song et al., 2009).

ZnO whiskers were grown in quartz tube by thermal oxidation method. Zinc powder was heated in a h... more ZnO whiskers were grown in quartz tube by thermal oxidation method. Zinc powder was heated in a horizontal quartz tube with a furnace at a temperature of 700C for 2 hr, under normal atmosphere. Three different kinds of the products can be obtained after the oxidation process. One is transparent whiskers located at the bottom of the quartz tube. Next is cotton-like bulk and the other is white, fluffy product. The products were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). It was found that the products composed of whiskers and tetrapod whiskers. The lengths and the diameter of whiskers were in the range of 10-240 mm and 0.20 4.60 mm, respectively while the percent of yield was up to 20% by weight. The lengths and the diameter of tetrapod whiskers were in the range of 3.15-10.63 mm and 0.132.64 mm while the percent of yield was up to 68% by weight.

Ceramics International, 2008

ABSTRACT

Sensors and Actuators B: Chemical

1-Dimensional Metal Oxide Nanostructures

Sensors and Actuators A: Physical, 2016

Advanced Materials Research, 2008

Platinum impregnated ZnO tetrapods were prepared and studied for the detection of ethanol vapor. ... more Platinum impregnated ZnO tetrapods were prepared and studied for the detection of ethanol vapor. ZnO tetrapods were synthesized by oxidation reaction technique by heating a mixer of zinc powder (99.99%) and hydrogen peroxide solution (30 wt.%) at 1,000oC in air. Platinum was impregnated by dropping hydrogen hexachloroplatinate (IV) hydrate, H2Cl6Pt.aq, solution with different concentration on ZnO tetrapods and then, heated at 350oC for 1 hr. The platinum impregnated ZnO tetrapods were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) for morphology and chemical composition, respectively. The particles were observed on the surface of ZnO tetrapods. The EDS spectrum suggested that the particles were platinum. Platinum impregnated ZnO tetrapods were tested ethanol sensing properties under ethanol concentration of 50-1,000 ppm. The ethanol sensing results indicated that the sensitivity of the sensors depended on the platinum i...

Key Engineering Materials, 2016

Magnesium oxide (MgO) nanostructures were synthesized by microwave-assisted thermal oxidation at ... more Magnesium oxide (MgO) nanostructures were synthesized by microwave-assisted thermal oxidation at various amount of activated carbon additive. The MgO nanostructures were characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffractrometry (XRD) and UV-Visible spectroscopy, respectivly. It was observed that, the obtained MgO have nanocube shape. The MgO nanostructures were applied as a blocking layer in ZnO dye-sensitized solar cells (DSSC). The photovoltage, photocurrent, and power conversion efficiency characteristics of DSSCs were measured under illumination of simulated sunlight obtained from a solar simulator with the radiant power of 100 mW/cm2. The DSSCs with MgO layer exhibited higher current density, open circuit voltage and photoconversion efficiency than those without MgO layer The optimum power conversion efficiency (PCE) was 2.49 % with short circuit current (Jsc) of 6.61 mA/cm2, the open circuit voltage (Voc) of 0.66 V and t...

ACS Applied Materials & Interfaces, 2015

Here, interlinked ZnO tetrapod networks (ITN-ZnO) have been realized by using microwave-assisted ... more Here, interlinked ZnO tetrapod networks (ITN-ZnO) have been realized by using microwave-assisted thermal oxidation. With this simple and fast process, a nanostructured ZnO morphology having tetrapodlike features with leg-to-leg linking is obtained. The electrical and ethanol-sensing properties related to the morphology of ITN-ZnO compared with those of other ZnO morphologies have also been investigated. It has been found that ITN-ZnO unexpectedly exhibits superior electrical and gas-sensing properties in terms of providing pathways for electron transport to the electrode. A UV sensor and a room-temperature gas sensor with improved performance are achieved. Therefore, ITN-ZnO is an attractive morphology of ZnO that is applicable for many new applications because of its novel properties. The novel properties of ITN-ZnO are beneficial for electronic, photonic, optoelectronic, and sensing applications. ITN-ZnO may provide a means to improve the devices based on ITN-ZnO.

Sensors and Actuators B: Chemical, 2012

Materials Science Forum, 2011

Zinc oxide tetrapods (T-ZnO) were synthesized using thermal oxidation technique from Zn powders m... more Zinc oxide tetrapods (T-ZnO) were synthesized using thermal oxidation technique from Zn powders mixed with hydrogen per oxide (H2O2). Through a detailed field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD) showed that the T-ZnO exhibited single crystalline hexagonal wurtzite structure. The leg tip of the T-ZnO was about 8.17±1.17 µm in length and 47.80 nm in diameter. The ethanol sensors, based on the T-ZnO and the T-ZnO doped with Au nanoparticles (Au/T-ZnO), were fabricated and investigated for the ethanol sensing properties. The ethanol sensor response of the T-ZnO and the Au/T-ZnO sensors was tested at the operating temperature of 260-360°C with the ethanol concentration of 50, 100, 500, and 1000 ppm. The results showed that the Au/T-ZnO sensors exhibited exceptionally higher sensitivity than the pure T-ZnO sensors for entire ethanol concentration with optimum temperature of 340°C and 320°C, respectively. This en...

Sensors and Actuators B: Chemical, 2010

In this paper, we propose a new and general formula to describe ethanol adsorption mechanism unde... more In this paper, we propose a new and general formula to describe ethanol adsorption mechanism underlying the response enhancement of ZnO nanostructure sensors. The derivation of sensor response formula based on basic chemical reaction at the sensor surface is presented. The formula can be used to explain response enhancement due to effect of metal doping, surface-to-volume ratio, and surface depletion layer. Thus, it can be regarded as a general formula to describe the sensor response characteristics of ZnO sensors. This general formula is a powerful tool for designing ZnO sensor at any desired sensor response. Furthermore, it is reasonable to expand this formula to explain other sensing materials and also to explain for different active gases.

Thin Solid Films, 2013

ABSTRACT The semiconducting layers of ZnO nanoparticles (ZN), ZnO powder (ZP) and ZnO nanopowder ... more ABSTRACT The semiconducting layers of ZnO nanoparticles (ZN), ZnO powder (ZP) and ZnO nanopowder (ZNP) were designed and fabricated for double-layered semiconducting photoelectrode in dye-sensitized solar cells (DSSCs). The under-layer was ZN, which was prepared by simple and cost-effective sparking technique onto F-doped tin oxide (FTO) glass substrate and its thickness was controlled by number of sparking cycles for 0, 10, 25, 50 and 100 rounds under atmospheric pressure. Then, ZP or ZNP was screened on to ZN to form double-layered photoelectrode. Here, the DSSC structures were FTO/double-layered ZnO/Eosin Y/electrolyte/Pt counterelectrode. The best results of DSSCs were observed with J(sc) of 4.71 mA/cm(2) and 5.56 mA/cm(2) and photoconversion efficiency of 1.11% and 1.14% at 50 sparking cycles for ZP and ZNP over-layers, respectively. The efficiency enhancement can be explained by combination effects of electron and light scattering. Moreover, the modified equation of short circuit current density was developed and effectively used to explain the efficiency enhancement.

Nanowires - Recent Advances, 2012

Nanowires, 2010

The metal-oxides are very interesting materials because they possess wide and universal propertie... more The metal-oxides are very interesting materials because they possess wide and universal properties including physical and chemical properties. For example, metal-oxides exhibit wide range of electrical property from superconducting, metallic, semiconducting, to insulating properties (Henrich & Cox, 1994). The wide ranges of properties makes metaloxide suitable for many applications including corrosion protection, catalysis, fuel cells, gas sensor, solar cells, field effect transistor, magnetic storage (Henrich, 2001), UV light emitters, detectors, piezoelectric transducers, and transparent electronics (Hsueh & Hsu, 2008) etc. Recently, nanostructures of metal-oxide such as nanowire, nanorod, nanobelt, nanosheet, nanoribbon, and nanotube have gained a great attention due to their distinctive and novel properties from conventional bulk and thin film materials for new potential applications. These unique properties cause by quantum confinement effect (Manmeet et al., 2006), lower dimensionality (Wang et al., 2008), change of density of state (Lyu et al., 2002), and high surface-to-volume ratio (Wangrat et al., 2009). Nanowires can be regarded as one-dimensional (1D) nanostructures which have gained interest for nanodevice design and fabrication (Wang et al., 2008). As an example of metaloxide nanowires, the materials are focused on zinc oxide (ZnO) and copper oxide (CuO). ZnO which is n-type semiconductor has been widely studied since 1935 with a direct band gap of 3.4 eV and large exciton binding energy of 60 meV at the room temperature (Coleman & Jagadish, 2006). ZnO has a wurtzite structure, while CuO, which is p-type semiconductor with narrow band gap of 1.2 eV , has a monoclinic crystal structure (Raksa et al., 2009). ZnO and CuO can be synthesized by various techniques such as pulse laser deposition (PLD)