Effect of Heat Treatment on Electrodeposited ZnSe on Vertically Aligned ZnO Nanorods for Photoelectrochemical Cell

2020 ◽  
Vol 307 ◽  
pp. 179-184
Author(s):  
Laimy Mohd Fudzi ◽  
Zulkarnain Zainal ◽  
Hong Ngee Lim ◽  
Sook Keng Chang ◽  
Asma Samsudin
Keyword(s):  
Thin Film ◽  
Heat Treatment ◽  
Band Gap ◽  
Zno Nanorods ◽  
Photocurrent Density ◽  
Band Gap Energy ◽  
Photoelectrochemical Cell ◽  
Halogen Lamp ◽  
Additional Layer ◽  
Znse Layer

Following successful growth of zinc oxide (ZnO) nanorods, a layer of zinc selenide (ZnSe) was electrodeposited onto the nanorods to further enhance its conversion efficiency in the photoelectrochemical (PEC) cell. The electrodeposited ZnSe layer onto the ZnO nanorods was subjected to heat treatment at 200, 250 and 300°C. The prepared films were characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis) to investigate the structural, morphological and compositional characteristics. Additionally, PEC conversion generated by the prepared thin films were tested with photocurrent measurements under calibrated visible illumination from a halogen lamp. Based on FESEM analysis, the thickness of ZnO thin film increased with temperature. However, the diameters of the ZnO nanorods were found to be in a decreasing trend upon heat treatment at higher temperature. The electrodeposited ZnSe layer at the potential of -0.7 V for 60 seconds (calcined at 200°C) possessed crystallite size of 20.1 nm. According to UV-Vis analysis, band gap energy measured was 2.8 eV, which is very close to standard ZnSe band gap value (2.7 eV). Additional layer of ZnSe electrodeposited enhanced thin film performance in terms of current density as much as 37.4% while having high photocurrent density of 0.2671 mAcm-2.

Influence of Applied Potential on Electrodeposited ZnSe/ZnO Nanostructured Films for Photoelectrochemical Cell

2021 ◽  
Vol 317 ◽  
pp. 463-470
Author(s):  
Laimy Mohd Fudzi ◽  
Zulkarnain Zainal ◽  
Hong Ngee Lim ◽  
Suhaidi B. Shafie ◽  
Sook Keng Chang
Keyword(s):  
Zno Nanorods ◽  
Reference Electrode ◽  
Average Diameter ◽  
Photocurrent Density ◽  
Band Gap Energy ◽  
Photoelectrochemical Cell ◽  
Potential Range ◽  
Halogen Lamp ◽  
Applied Potential ◽  
Conversion Performance

Zinc oxide (ZnO) nanorods is widely investigated due to its high photoelectrochemical conversion performance. Further enhancement may be afforded by introducing a metal chalcogenide sensitization layer such as zinc selenide (ZnSe). In this study, ZnO nanorods were electrodeposited with ZnSe at potential range from -0.5 V to -0.9 V vs Ag/AgCl reference electrode. Structural, morphological and optical properties of ZnSe electrodeposited were investigated as a function applied potential by using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). ZnSe electrodeposited for 15 minutes at -0.7 V showed crystallite size of 20.13 nm with the lowest band gap energy of 2.97 eV. The existence of ZnSe particles with the size of 41.8 nm were proven by FESEM images, after ZnSe particles were electrodeposited onto ZnO nanorods that have an average diameter of 62.6 nm and length of 1.6 µm. The photocurrent density generated by samples were measured in a three-electrodes cell incorporated with halogen lamp. The photocurrent generated increased between -0.5 V to -0.7 V before dropped at higher applied potential due to hydrogen evolution process which affected the thin film quality, ultimately affecting photoconversion performance. The highest photocurrent density of 0.2621 mAcm-2 was recorded for samples prepared at -0.7 V vs Ag/AgCl.

Effect of the ZnO Rods Growth Time to the Conductivity of ZnO Thin Film Combined with N3 Dye

2011 ◽  
Vol 383-390 ◽  
pp. 3286-3290
Author(s):  
Engku Abd Engku Ali Ghapur ◽  
W.A. Dhafina ◽  
S. Hasiah ◽  
N.A.N. Ali
Keyword(s):  
Thin Film ◽  
Aspect Ratio ◽  
Band Gap ◽  
Zno Nanorods ◽  
Hydrothermal Process ◽  
Hydrothermal Solution ◽  
Band Gap Energy ◽  
Growth Time ◽  
Gap Energy ◽  
Zno Rods

In this work, ZnO nanorod has been grown by hydrothermal solution method. The samples were prepared by two stages. The first stage was seeding process where the ZnO nanoparticles are spin-casted onto ITO coated glasses and the second stage was hydrothermal process. The morphology of nanorods were investigated by using scanning electron microscope (SEM) and different of length and diameter of nanorods with different growth durations have been observed. The differences of diameters and aspect ratio of nanorods have affected the optical and electrical properties of the ZnO-coated thin film with dye due to its surface area and morphologies of growth rod. Aspect ratio of ZnO nanorods increases by increasing the reaction time (growth time). From the band gap energy study, the thin film with the longest ZnO nanorods growth time has the lowest band gap energy (3.55 eV). The higher aspect ratio of the nanorod affected the conductivity, by increasing the conductivity when combined with N3 dye.

Band-Gap Energy Dependence of Emission Spectra in Rare Earth-Doped Zn(1-x)CdxS Thin Film Electroluminescent Devices

1992 ◽  
Vol 31 (Part 1, No. 2A) ◽  
pp. 295-300 ◽  
Author(s):  
Noboru Miura ◽  
Takashi Sasaki ◽  
Hironaga Matsumoto ◽  
Ryotaro Nakano
Keyword(s):  
Thin Film ◽  
Rare Earth ◽  
Band Gap ◽  
Energy Dependence ◽  
Emission Spectra ◽  
Band Gap Energy ◽  
Electroluminescent Devices ◽  
Gap Energy ◽  
Rare Earth Doped

Fabrication and Photoelectrochemical Characterization of Fe, Co, Ni and Cu-Doped TiO2 Thin Films

2013 ◽  
Vol 764 ◽  
pp. 266-283 ◽  
Author(s):  
Ibram Ganesh ◽  
Rekha Dom ◽  
P.H. Borse ◽  
Ibram Annapoorna ◽  
G. Padmanabham ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Metal Ions ◽  
Band Gap ◽  
Metal Ion ◽  
Band Gap Energy ◽  
Chemical Compositions ◽  
Gap Energy ◽  
Glass Substrates ◽  
Photoelectrochemical Characterization

Different amounts of Fe, Co, Ni and Cu-doped TiO2 thin films were prepared on fluorine doped tin oxide (FTO) coated soda-lime glass substrates by following a conventional sol-gel dip-coating technique followed by heat treatment at 550 and 600°C for 30 min. These thin films were characterized for photo-current, chronoamperometry and band-gap energy values. The chemical compositions of metals-doped TiO2 thin films on FTO glass substrates were confirmed by XPS spectroscopic study. The metal-ions doped TiO2 thin films had a thickness of <200 nm="" optical="" transparency="" of="">80%, band-gap energy of >3.6 eV, and a direct band-to-band energy transition. The photoelectrochemical (PEC) studies revealed that all the metal-ions doped TiO2 thin films exhibit n-type semi-conducting behavior with a quite stable chronoamperometry and photo-currents that increase with the increase of applied voltage but decrease with the dopant metal-ion concentration in the thin film. Furthermore, these thin films exhibited flat-band potentials amenable to water oxidation reaction in a PEC cell. The 0.5 wt.% Cu-doped TiO2 thin film electrode exhibited an highest incident photon-to-current conversion efficiency (IPCE) of about 21%.

Photoelectrochemical Properties of Alkali-treated Sodium Titanate Nanorods

2015 ◽  
Vol 1784 ◽  
Author(s):  
Mingu Kim ◽  
Gwanghyo Choi ◽  
Daeheung Yoo ◽  
Kwangmin Lee
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Band Gap ◽  
Heat Treatment Temperature ◽  
Alkali Treatment ◽  
Sodium Titanate ◽  
Band Gap Energy ◽  
Treatment Temperature ◽  
Photoelectrochemical Properties ◽  
Gap Energy

ABSTRACTThe band gap energy of the TiO2 photocatalytic is high at 3.2 eV. Ultraviolet (UV) light irradiation (<388nm) is required for the photocatalytic application. The lowering the band gap energy of TiO2 and enlarging light absorbing area are effective ways to enhance the efficiency of photocatalytic activity. Furthermore, the morphology and crystal structure of nanosized TiO2 considerably influences its photocatalytic behavior.In this study, sodium titanate nanorods were formed using an alkali-treatment and were heat treated at different temperatures. The photoelectrochemical properties of sodium titanate nanorods was measured as a function of heat treatment temperature. The nanorods were prepared on the surface of Ti disk with a diameter of 15mm and a thickness of 3mm. Ti disk was immersed in 5 M NaOH aqueous solution at a temperature of 60 °C for 24 h. Morphology of sodium titanate nanorods was observed using FE-SEM. Crystal structure of sodium titanate nanorods was analyzed using X-ray diffractometer. Photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) was used to evaluate photoelectrochemical properties of sodium titanate nanorods. The thin amorphous sodium titanate layer was formed during alkali-treatment. The sodium titanate layer was changed to nanorods after heat treatment at a temperature of 700 °C. The thickness and length of sodium titanate nanorods obtained at 700 °C were around 100 nm and 1μm, respectively. The crystal structure of sodium titanate was identified with Na2Ti6O13. Above 900 °C, the morphology of nanorods changed to agglomerated shape and the thickness of nanorods increased to 1 μm. The lowest value of PL was obtained at a temperature of 700 °C, while nonalkali treated specimen showed the highest value of PL. EIS revealed that polarization resistance at interface between sodium titanate nanorods and electrolyte was increased with increasing heat treatment temperature.

Effect of ZnO on a Superhydrophilic Self-Cleaning Properties of TiO2/SiO2 Thin Film on Glass Slide Substrate

2015 ◽  
Vol 1131 ◽  
pp. 237-241 ◽  
Author(s):  
Akkarat Wongkaew ◽  
Chanida Soontornkallapaki ◽  
Naritsara Amhae ◽  
Wichet Lamai
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Visible Light ◽  
Band Gap ◽  
Sol Gel ◽  
Dip Coating ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Coating Method ◽  
Dip Coating Method

This work aims to study the effect of ZnO containing in TiO2/SiO2 film on the superhydrophilic property after exposed to different types of light. The metal solutions were prepared by sol-gel technique and the film was deposited on glass slides by dip coating method. The parameter studied was the amount of ZnO in the TiO2/SiO2 film. The contents of ZnO were 5-20% weight (increased by 5%). The amount of TiO2 was constant at 30% weight. The obtained films were analyzed for their roughness. The results indicated that film roughness changed according to the ZnO contents. With 5%ZnO in the thin film, the roughness was 0.726 nm while 20%ZnO obtained the roughness of 2.128 nm. UV-Vis spectrophotometer was used for measuring of transmittance of films. At wavelength of 550 nm, the transmittances of each film were greater than 90%. Band gap energy of each film was calculated from the transmittance data. It was found that the average band gap energy of the films was 2.47 eV. Then, the films contained various amount of ZnO were grouped into 2 sets. The first set was exposed to visible light while the other set was exposed to UV. The duration of exposure was 5 hr. Both sets of films after exposed to any light were kept in a black box controlled relative humidity of 85%. Each film was measured contact angle every day. It was found that the 30%TiO2/5%Zn/SiO2 film exposed to visible light showed the best superhydrophilic property. The contact angle was about 0-5° within 3 days. This may due to the reduction of band gap energy in the presence of ZnO in TiO2/SiO2 films to 2.41 eV and the roughness of the film.

A correlation for crystallite size of undoped ZnO thin film with the band gap energy – precursor molarity – substrate temperature

Optik ◽  
2014 ◽  
Vol 125 (3) ◽  
pp. 1303-1306 ◽  
Author(s):  
Said Benramache ◽  
Okba Belahssen ◽  
Ali Arif ◽  
Abderrazak Guettaf
Keyword(s):  
Thin Film ◽  
Substrate Temperature ◽  
Band Gap ◽  
Crystallite Size ◽  
Band Gap Energy ◽  
Zno Thin Film ◽  
Gap Energy

scholarly journals Development of Thin Film Amorphous Silicon Tandem Junction Based Photocathodes Providing High Open-Circuit Voltages for Hydrogen Production

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
F. Urbain ◽  
K. Wilken ◽  
V. Smirnov ◽  
O. Astakhov ◽  
A. Lambertz ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Hydrogen Production ◽  
Amorphous Silicon ◽  
Open Circuit ◽  
Direct Application ◽  
Photoelectrochemical Cell ◽  
Halogen Lamp ◽  
Tandem Solar Cells ◽  
Open Circuit Voltages

Hydrogenated amorphous silicon thin film tandem solar cells (a-Si:H/a-Si:H) have been developed with focus on high open-circuit voltages for the direct application as photocathodes in photoelectrochemical water splitting devices. By temperature variation during deposition of the intrinsic a-Si:H absorber layers the band gap energy of a-Si:H absorber layers, correlating with the hydrogen content of the material, can be adjusted and combined in a way that a-Si:H/a-Si:H tandem solar cells provide open-circuit voltages up to 1.87 V. The applicability of the tandem solar cells as photocathodes was investigated in a photoelectrochemical cell (PEC) measurement set-up. With platinum as a catalyst, the a-Si:H/a-Si:H based photocathodes exhibit a high photocurrent onset potential of 1.76 V versus the reversible hydrogen electrode (RHE) and a photocurrent of 5.3 mA/cm2at 0 V versus RHE (under halogen lamp illumination). Our results provide evidence that a direct application of thin film silicon based photocathodes fulfills the main thermodynamic requirements to generate hydrogen. Furthermore, the presented approach may provide an efficient and low-cost route to solar hydrogen production.

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