Photoelectrochemical Performance of Smooth TiO 2

The formation of self-organized titanium dioxide (TiO2) nanotube arrays without bundling or clustering is essential for their high efficiency in photoelectrochemical (PEC) application. The present paper reports on the use of different temperatures to control the specific architecture of nanotube arrays and effective cleaning techniques to ensure the formation of clean TiO2 nanotube surface. The wall thickness of nanotube arrays could be controlled from 12.5 nm to 37.5 nm through different anodization temperature ranging from 10°C to 80°C. Furthermore, ultrasonic cleaning combined with acetone showed the high-ordered TiO2 nanotube arrays without morphological disorder, bundling, and microcrack problems. Based on the results obtained, a higher PEC response of 1 mA/cm2 and a photoconversion efficiency of 1.3% could be achieved using a wall thickness of 12.5 nm and defect-free TiO2 nanotube arrays for low charge transfer resistance

Modification of One-Dimensional TiO 2

One-dimensional calcium oxide (CaO-) based titanium dioxide (TiO2) nanotubes were successfully synthesized through a rapid electrochemical anodization and chemical wet impregnation techniques. In this study, calcium nitrate solution was used as a calcium source precursor. The reaction time and concentration of calcium source on the formation of CaO-TiO2 nanotubes were investigated using field emission microscopy, energy dispersion X-ray spectroscopy, and X-ray diffraction. The adsorption capacity of CO2 was determined by thermal gravimetric analyzer. A maximum of 4.45 mmol/g was achieved from the CaO-TiO2 nanotubes (6.64 at% of Ca). The finding was attributed to the higher active surface area for CaO to adsorb more CO2 gas and then formed CaCO3 compound during cyclic carbonation-calcination reaction

Development Of Wo3-Tio2 Nanotube Arrays For Water Electrolysis

Penjanaan hidrogen solar melalui elektrolisis air adalah sasaran utama untuk pembangunan ekonomi hidrogen secara lestari bagi sistem tenaga masa depan. Pembentukan TiO2 tiubnano yang bebas daripada kelompok adalah penting dalam aplikasi elektrolisis air supaya mencapai kecekapan yang tinggi. Kajian terperinci terhadap kesan komposisi elektrolit, masa penganodan, keupayaan elektrik, suhu penganodan dan suhu penyepuhlindapan telah dilaksanakan bagi mengawal susunan dan geometri tiubnano. Susunan tiubnano TiO2 yang mempunyai permukaan dinding licin dan nisbah aspek yang tinggi telah berjaya disintesis dalam glikol etilena yang mengandungi 5 wt% NH4F dan 5 wt% H2O2 melalui kaedah penganodan pada 60 V selama 1 jam. H2O2 digunakan sebagai pembekal oksigen untuk meningkatkan kadar pengoksidaan dan seterusnya meningkatkan kadar pembentukan tiubnano dalam kajian ini. Sehubungan dengan itu, didapati bahawa penambahan hidrogen peroksida ke dalam elektrolit dalam selang masa 10 min menghasilkan tiubnano yang lebih panjang (~ 13 μm) dengan diameter ~ 140 nm. Usaha berterusan telah dilaksanakan bagi meningkatkan lagi prestasi elektrolisis air dengan mendeposisi WO3 pada TiO2 tiubnano melalui teknik pemercikan RF dan pengisitepuan basah. WO3-TiO2 tiubnano yang dipercik dengan daya pemercikan 50 W selama 0.5 min serta disepuhlindap pada 400 °C telah menunjukkan foto-arus sebanyak 2.4 mA/cm2 yang tinggi dengan kecekapan penukaran foto sebanyak 6.2 %. Peningkatan prestasi sebanyak dua kali ganda telah dicatatkan berbanding dengan TiO2 tiubnano yang asal. Sebaliknya, TiO2 tiubnano yang dicelupkan dalam 0.3 mM larutan APT selama 1 jam menunjukkan foto-arus sebanyak 2.1 mA/cm2 dengan kecekapan penukaran foto sebanyak 5.1 %. WO3-TiO2 tiubnano yang dihasilkan melalui teknik pemercikan RF mencatatkan prestasi elektrolisis air yang lebih tinggi berbanding dengan teknik pengisitepuan basah. Penemuan ini menunjukkan bahawa pengenapan W6+ spesies dalam kekisi TiO2 dengan tenaga kinetik yang tinggi (pemercikan RF) mencapai prestasi elektrolisis air yang lebih baik berbanding dengan proses resapan daripada W6+ spesies ke dalam kekisi TiO2 (pengisitepuan basah). Kehadiran unsur W di bawah 1 at% dalam TiO2 menunjukkan peningkatan foto-arus dan kecekapan penukaran foto kerana ia akan bertindak sebagai pengantara yang berkesan untuk memerangkap elektron dan mengurangkan rekombinasi elektron-lohong. Sebaliknya, kandungan WO3 yang berlebihan akan membentuk akumulasi pada permukaan tiubnano dan mengakibatkan prestasi elektrolisis air menjadi rendah kerana lapisan asing ini akan bertindak sebagai pusat rekombinasi elektron-lohong. Solar hydrogen generation from water electrolysis is a key target for the development of sustainable hydrogen economy for future energy system. The formation of self-organized TiO2 nanotubes without bundling is essential for high efficiency in photoelectrochemical (PEC) water electrolysis application. Comprehensive investigations on different parameters, such as composition of electrolyte, anodization time, anodization voltage, anodization temperature and heat treatment temperature were conducted in order to control the specific architecture of nanotubes. Highly ordered and smooth TiO2 nanotubes were successfully synthesized through anodization of Ti foil in ethylene glycol containing 5 wt% of NH4F and 5 wt% of H2O2 at 60 V for 1 h. In this study, H2O2 was used as oxygen provider to increase the oxidation rate for synthesizing nanotubes at a rapid rate. It was found that addition of H2O2 at 10 min intervals formed longer nanotubes (~ 13 μm) with larger pore diameter (~ 140 nm). Continuous efforts have been exerted to further improve the PEC water splitting performance by incorporating an optimum content of WO3 into TiO2 nanotubes using RF sputtering and wet impregnation techniques. It was found that TiO2 nanotubes sputtered at 50 W for 0.5 min and subsequently heat treated at 400 °C demonstrated a maximum photocurrent density of ~ 2.4 mA/cm2 with photoconversion efficiency ~ 6.2 %. This performance was approximately two times higher than the pure TiO2 nanotubes. On the other hand, TiO2 nanotubes that dipped into the 0.3 mM ammonium paratungstate (APT) solution for 1 h showed photocurrent density of ~ 2.1 mA/cm2 with photoconversion efficiency of ~ 5.1 %. The WO3-TiO2 nanotubes prepared by RF sputtering exhibited higher PEC water splitting performance than that of wet impregnation. These findings deduced that W6+ species incorporated within TiO2 lattice by high kinetic energy process (RF sputtering) exhibited better PEC performance than the diffusion of W6+ species into TiO2 lattice (wet impregnation). The presence of W element below 1 at% in TiO2 showed an improvement of photocurrent density and photoconversion efficiency because it acted as an effective mediator to trap the photo-induced electrons and minimize the recombination of charge carriers. By contrast, excessive content of WO3 loading on the wall surface of TiO2 nanotubes resulted in poor PEC water splitting performance because it formed independent layers that acted as recombination centers for the charge carriers

A Novel Solar Driven Photocatalyst: Well-Aligned Anodic WO3 Nanotubes

Well-aligned anodic tungsten trioxide (WO3) nanotubes were successfully synthesized by anodization of W foil at 40V in a bath with electrolyte composed of 1M of sodium sulphate (Na2SO4) and 0.5 wt% ammonium fluoride (NH4F). The effect of electrochemical anodization times on the formation mechanism of anodic WO3 nanotubular structure was investigated. It was found that minimumof 15 min is required for completing transformation fromWfoil toWO3 nanotubular structurewith an average diameter of 50nmand length of 500 nm.Thephotocatalytic ability of the sampleswas evaluated by degradation of methyl blue (MB) dye.Theresults indicate that the surface morphology of anodicWO3 affected the photocatalyticMBdegradation significantly under solar illumination

Pembangunan e-modul pembelajaran enjin diesel untuk kursus teknologi automotif

"Penyelidikan ini adalah untuk membangunkan satu reka bentuk e-modul pembelajaran pelajar kursus Teknologi Automotif di kolej vokasional. Tujuan penyelidikan ini adalah bagi mengenalpasti kesesuaian elemen yang digunakan dalam modul dan reka letak papan cerita yang dibangunkan. Penggunaan e-modul dalam modul vokasional ini dapat memudahkan pemahaman pelajar dan cemerlang di dalam pentaksiran kompetensi. Modul menggunakan Model ADDIE sebagai model dan prinsip pembangunan bahan multimedia serta prinsip hueristik kebolehgunaan bagi pembangunan modul interaktif ini. Proses pembangunan modul menggunakan perisian CourseLab, Audacity, Freemake Video Converter, GIMP yang merupakan antara perisian percuma dan perisian sumber terbuka. Hasil pembangunan modul diuji sebanyak dua kali ke atas seramai 30 orang pelajar Kursus Teknologi Automotif yang terlibat di dalam penyelidikan ini dan 7 orang pensyarah dari kolej vokasional dipilih sebagai responden kajian. Soal selidik digunakan sebagai instrumen oleh pengkaji dalam kajian ini. Set soal selidik ini terdiri dari tiga set iaitu untuk kesesuaian elemen modul, kesesuaian papan cerita dan pembangunan e-modul pembelajaran. Soalan-soalan yang dikemukakan pada ketiga-tiga set akan dijawab berdasarkan skala likert. Maklumat dan data yang diperoleh akan dianalisis dengan menggunakan Statistical Packages for Social Sciences (SPSS). Kesimpulan daripada data dan maklumat yang diperolehi menunjukkan satu e-modul pembelajaran dapat dibangunkan dengan mempunyai aspek rekabentuk (skor min = 4.74), aspek persembahan (skor min = 4.67) dan aspek mesra pengguna (skor min = 4.69) yang dapat menarik minat belajar berdasarkan pada purata keseluruhan skor min.

On character table of Clifford groups

Based on a presentation of $\mathcal{C}_n$ and the help of [GAP], we construct the character table of the Clifford group $\mathcal{C}_n$ for $n=1,2,3$. As an application, we can efficiently decompose the (higher power of) tensor product of the matrix representation in those cases. Our results recover some known results in [HWW, WF] and reveal some new phenomena. We prove that the trivial character is the only linear character for $\mathcal{C}_n$ and hence $\mathcal{C}_n$ equals to its commutator subgroup when $n\geq 3$. A few conjectures about $\mathcal{C}_n$ for general $n$ are proposed.Comment: 13 pages; comments and suggestions are welcom

Fabrication of multianalyte CeO2 nanograin electrolyte–insulator–semiconductor biosensors by using CF4 plasma treatment

Multianalyte CeO2 biosensors have been demonstrated to detect pH, glucose, and urine concentrations. To enhance the multianalyte sensing capability of these biosensors, CF4 plasma treatment was applied to create nanograin structures on the CeO2 membrane surface and thereby increase the contact surface area. Multiple material analyses indicated that crystallization or grainization caused by the incorporation of flourine atoms during plasma treatment might be related to the formation of the nanograins. Because of the changes in surface morphology and crystalline structures, the multianalyte sensing performance was considerably enhanced. Multianalyte CeO2 nanograin electrolyte–insulator–semiconductor biosensors exhibit potential for use in future biomedical sensing device applications

An Empirical Investigation on Credit Card Repayment Pattern of Academicians in Malaysia

The credit card market has witnessed tremendous growth resulting from a paradigm shift in technology. The genuine usage of credit cards as a form of convenience has diverged to overspending, irresponsibility, revolving liability and bankruptcy. This implies that possession of credit cards has brought about a change in users repayment behavior. Thus, this study aims to determine academicians credit card repayment pattern in a private tertiary institution in Malaysia. The dependent variable is the repayment pattern and the independent variables that serve as the attributes include personal attitude and spending pattern, while gender and parenthood serve as the moderating variables. Findings revealed that personal attitude and spending pattern were important attributes in determining the repayment pattern among the academicians. Gender and parenthood were found to play a moderating role in the repayment pattern. Findings from this study is expected to facilitate the government and credit card companies to work towards nurturing a financially healthier and informed society, and also to each out positively to the younger generations through the influence of the academicians

New insights into the photocatalytic endocrine disruptors dimethyl phathalate esters degradation by UV/MWCNTs-TiO2 nanocomposites

Dimethyl phthalate esters (DMPEs) are considered to be endocrine disruptors and environmentally hazardous materials in plastic industries wastewater because of its low solubility and accumulated persistent toxicity. In the present study, MWCNTs/TiO2 nanocomposites were fabricated by modified sol-gel technique using titanium isopropoxide as titanium oxide sources and purified MWCNTs, to degrade DMPEs through photocatalysis using UV irradiation. The effect of MWCNTs loading (3–15 wt %) on TiO2 and the photocatalytic performance of DMPEs in aqueous solution by UV/MWCNTs/TiO2 nanocomposites were investigated. For experiments conducted with the same illumination time, the photodegradration of DMPEs was enhanced with increasing the MWCNTs contents from 3 to 10 wt % and then decreased with a further enhancement to 15 wt %. Basically, the presence of MWCNTs in the nanocomposites can lead to the decrease in the relative amount of TiO2 in the photocatalyst and then to the decrease of the photogenerated carriers. This is because the same amount of photocatalyst was added for the photoreaction, and hence, the photodegradation of DMPEs decreases especially for the nanocomposites containing MWCNTs exceed than 10 wt %. The presence of functional group (COOH) on the MWCNTs surface would help the achievement of direct chemical bonding between MWCNTs and the TiO2 nanoparticles, resulting in the synergistic effect of MWCNTs and TiO2 where the flow of photogenerated electrons in the space charge region to the MWCNTs surface. A method based on high-performance liquid chromatography (HPLC) was developed to study the degraded DMPEs samples produced after exposure to UV light