Radiation and Temperature Effects on Conductivity and Dielectric Properties of Poly (Vinyl Alcohol)-Potassium Hydroxide-Propylene Carbonate

The physical and chemical properties of polymeric materials can be modified by treatment with ionizing radiation. This radiation processing technique has been used to modify the structural and electrical properties of polymer composites for use as electrical devices. Alkaline composite polyrner electrolytes (ACPEs) are materials that have attracted great attention for their vast application in the development of solid-state ionic devices. The materials have their chemical and electrical properties change with radiation dose allowing modification of the electrolytes in the solid state form. One serious problem of the ACPEs is low ionic conductivity at room temperature because they have a tendency to crystallize. In this study radiation-processing technique was chosen to increase the ionic conductivity at room temperature. The ACPE consists of poly(viny1 alcohol) (PVA) as the host polymer, potassium hydroxide (KOH) as an ionic blend and propylene carbonate (PC) as a plastisizer. The compositions of KOH and PC were varied from 40 to 70%. The electrolytes were prepared by chemical method and the finished films were obtained by solvent-casting technique. The films were irradiated with 1.25 MeV gamma rays with dose from 0 to 200 kGy at room temperature. The sample of irradiated and unirradiated films of different compositions was placed between two parallel-plate metal electrodes and the conductivity and dielectric properties were measured using an impedance analyzer at different frequencies ranging from 20 Hz to 1 MHz. For the unirradiated samples, the conductivity and dielectric properties were also measured at different temperatures of narrow range from room temperature to 343 K. The X-ray diffraction (XRD) measurements were performed to characterize the change of molecular structure of the electrolytes with radiation dose and compositions of the blend and plastisizer. The results show that the ACPE sample of PVA-KOH (40 wt.%)- PC (60 wt.%) irradiated with dose 200 kGy exhibits the highest ionic conductivity of 2.7 x 10'~s cm-' at room temperature. For ACPE sample with PVA-KOH (40 wt.%)-PC (60 wt.%) the highest ionic conductivity value is 7.8 x scm-' at 343 K. The results show that the frequency dependent conductivity and dielectric constant of the ACPEs depend on radiation dose, temperature and composition of the blends and plastisizer. From the XRD analysis, the molecular structure of the electrolytes change from semi-crystalline to amorphous when the composition of PC increased to 60% and the radiation dose increased to 200 kGy. Finally, we have demonstrated that radiation processing can be used to modify ACPEs to increase their ionic conductivity for the development of solidstate ionic devices

Effects of gamma radiation treatment and plasticizer on alkaline solid polymer electrolytes

Alkaline solid polymer electrolyte films have been prepared by the solvent-casting method. Gamma radiation treatment and propylene carbonate plastisizer were used to improve the ionic conductivity of .the electrolytes at ambient temperature. The structure of the irradiated electrolytes changes from semi-crystalline to amorphous, indicating that the crosslinking of the polymer has been achieved at a dose of 200 kGy. The ionic conductivity at room temperature of PVA/KOH blend increases from 10-7 to 10-3 Scm-1 after the PVA crosslinking and when the plasticizer concentration was increased from 20 to 30%

Recent Characterisation of Sol-Gel Synthesised TiO2 Nanoparticles

High demand and current applications have led to continuous study and subsequent improvement of TiO2 nanoparticles. The versatility of the sol-gel method allows employing different process parameters to influence the resultant properties of TiO2 nanoparticles. The evaluation and characterisation process of the synthesised TiO2 nanoparticles commonly involves a series of methods and techniques. Such characterisation methods include phase, structural, morphology and size analysis. A combination of data from these evaluations provides the relationship between the synthesis parameters and the end properties of TiO2 nanoparticles. Apart from the research findings on TiO2 nanoparticles, the characterisation used to obtain these findings is equally important. Thus, this chapter highlights the recent characterisation techniques and practices employed for TiO2 nanoparticles synthesised by the sol-gel method

Prestasi pemangkin Pt/rGO menggunakan teknik susunan berlapis untuk elektrod lawan bagi sel suria terpeka pewarna

Filem nipis elektrod lawan platinum (Pt) dan grafin oksida terturun (rGO) dengan teknik susunan berlapis dihasilkan dengan menggunakan kaedah “doctor blade”. Lapisan pertama dengan perlekatan secara langsung pada substrat kaca yang bersalut timah oksida terdop fluorin (FTO) adalah filem nipis grafin dan lapisan kedua di atas lapisan grafin adalah filem nipis Pt. Ujikaji dengan menggunakan pembelauan sinar-X (XRD) dan spektroskopi daya atom (AFM) masing-masing telah dijalankan ke atas filem-filem nipis untuk menentukan pembentukan struktur hablur dan kekasaran permukaan filem nipis. Saiz hablur ditentukan dari data XRD dan menunjukkan bahawa filem nipis Pt/rGO-10 mempunyai saiz hablur yang bersesuaian untuk aktiviti pemangkin yang lebih baik. Bagi analisis kekasaran permukaan dari imej AFM, filem-filem nipis Pt dan Pt/rGO mempamerkan permukaan yang lebih kasar berbanding filem nipis rGO. Filem-filem nipis tersebut kemudiannya dianalisis menggunakan mikroskop elektron imbasan pancaran medan (FESEM) untuk memerhatikan perlekatan filem nipis Pt dan rGO ke atas substrat kaca FTO dalam imej berskala nano. Aktiviti pemangkin setiap filem nipis diukur menggunakan kitaran voltammetri (CV). Elektrod lawan Pt/rGO yang mengandungi 10μl cecair grafin oksida disimbolkan sebagai Pt/rGO-10 mempunyai aktiviti pemangkin yang lebih tinggi berbanding Pt. Filem nipis Pt/rGO-10 mencatatkan ketumpatan arus tertinggi pada -3.075 mA/cm-2 yang menunjukkan aktiviti pemangkin yang tertinggi pada elektrod lawan. Maka, filem nipis elektrod lawan Pt/rGO dianggap setanding dengan bahan konvensional elektrod lawan iaitu Pt. Oleh itu, elektrod lawan Pt/rGO-10 dijangka dapat meningkatkan prestasi sel suria terpeka pewarna

Kesan ketebalan filem terhadap fotoelektrokimia titania dioksida (TiO2) yang disediakan melalui kaedah pemendapan bantuan aerosol wap kimia (AACVD)

Titanium oksida (TiO2) merupakan semikonduktor yang mempunyai jurang jalur yang besar dengan ciri-ciri foto penukaran dalam spektra UV sesuai digunakan dalam pelbagai aplikasi. Dalam penyelidikan ini, kaedah pemendapan bantuan aerosol wap kimia (AACVD) digunakan bagi menghasilkan lapisan filem TiO2 dengan ketebalan yang berbeza berdasarkan tempoh pemendapan yang dikenakan (3, 5 dan 7 min). Lapisan filem dimendapkan pada suhu 450oC. Melalui kedah AACVD, lapisan TiO2 yang dimendapkan di atas kaca FTO (florin dop tin oksida) akan menjadi lebih nipis dan struktur lapisan menjadi lebih padat.Titanium diisopropoxide bis(acetylacetonate) dan etanol digunakan untuk menghasilkan pelopor AACVD. Ciri morfologi dan ketebalan filem nipis TiO2 diuji menggunakan mikroskopi daya atom (AFM) yang menunjukkan permukaan berliang pada filem nipis tersebut. Ciri optik filem nipis TiO2 diuji menggunakan spektra pancaran ultra-lembayung cahaya nampak (UV-Vis) dan keputusan menunjukkan filem nipis memberikan ketelusan yang tinggi pada kawasan kelihatan berdasarkan jurang jalur yang diperolehi. Prestasi filem nipis dicirikan menggunakan voltammetri sapuan linear (LSV) dan spektroskopi impedans elektrokimia (EIS). TiO2-5 min memperoleh purata ketebalan 61 nm melihatkan prestasi J-V terbaik iaitu 6.30 x 10-4 A/cm-2 dan memberikan rintangan cas yang terendah. Tambahan, pemendapan filem menunjukkan kelekatan yang baik pada substrat, kebolehkeluaran semula dan permukaan filem nipis yang sekata. Berdasarkan keputusan yang diperolehi, TiO2 yang disediakan menggunakan kaedah AACVD sangat sesuai digunakan dalam pelbagai aplikasi seperti sel suria generasi ketiga yang memerlukan filem nipis dengan ketebalan yang rendah, berliang, ketelusan yang tinggi, fotoaktif, dan stabil

Co-sensitization of natural sensitizers extracted from rengas (Gluta spp.) and mengkulang (Heritiera elata) wood with ruthenium dye (N719) to enhance the performance of dye-sensitized solar cells

In this study, photovoltaic performance was improved when two natural sensitizers, namely, rengas (Gluta spp.) and mengkulang (Heritiera elata), were mixed with ruthenium (N719) sensitizer. Five different ratios were prepared and their performances were compared with individual sensitizers. The components of the sensitizers were analyzed via ultraviolet–visible spectrophotometry and Fourier transform infrared spectroscopy. The band gap values and the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO-LUMO) levels were calculated using data obtained from photoluminescence analysis and cyclic voltammetry. The mengkulang: N719 (80%:20%) sensitizer exhibits the highest conversion efficiency (ŋ), which is 0.58% with an open circuit voltage (Voc) of 0.63 V, a short circuit photocurrent density (Jsc) of 2.1 mA/cm2, and a fill factor (ff) of 0.44. By contrast, the individual mengkulang sensitizer presents a poor conversion efficiency (ŋ) of 0.16%

New insights into Se/BiVO4 heterostructure for photoelectrochemical water splitting: a combined experimental and DFT study

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Monoclinic clinobisvanite BiVO4 is one of the most promising materials in the field of solar water splitting due to its band gap and suitable VBM position. We have carried out a comprehensive experimental and periodic density functional theory (DFT) simulations of BiVO4 heterojunction with Selenium (Se/BiVO4), to understand the nature of heterojunction. We have also investigated contribution of Se to higher performance by effecting morphology, light absorption and charge transfer properties in heterojunction. Electronic properties simulations of BiVO4 shows that its VBM and CBM are comprised of O 2p and V 3d orbitals, respectively. The Se/BiVO4 heterojunction has boosted the photocurrent density by three fold from 0.7 to 2.2 mAcm-2 at 1.3 V vs. SCE. The electrochemical impedance and Mott-Schottky analysis consequence favorable charge transfer characteristics which account for the higher performance in Se/BiVO4 compared to the BiVO4 and Se. Finally, spectroscopic, photoelectrochemical and DFT evident that Se makes a direct Z-scheme (band alignments) with BiVO4 where the photoexcited electron of BiVO4 recombine with the VB of Se, consequences electron-hole separation at Se and BiVO4, respectively as a result enhanced photocurrent is obtained.The authors would like to thank the National University of Malaysia for the financial support from grants GUP-2016-089. One of us (H.U) acknowledges the NOTUR supercomputing facilities within the project nn4608

Properties of zinc tin oxide thin film by aerosol assisted chemical vapor deposition (AACVD)

This study focuses on the properties of ZTO which have been deposited by a low-cost method namely aerosol assisted chemical vapor deposition (AACVD). The precursors used in this method were zinc acetate dihidrate and tin chloride dihydrate for ZTO thin film deposition. Both precursors were mixed and stirred until fully dissolved before deposition. The ZTO was deposited on borosilicate glass substrate for the investigation of optical properties. The films deposited have passed the scotch tape adherence test. XRD revealed that the crystal ZTO is slightly in the form of perovskite structure but several deteriorations were also seen in the spectrum. The UV-Vis analysis showed high transmittance of ∼85% and the band gap was calculated to be 3.85 eV. The average thickness of the film is around 284 nm. The results showed that the ZTO thin films have been successfully deposited by the utilization of AACVD method

Kebergantungan suhu dengan penggunaan tiub kuarza relau ke atas sel suria dwi-muka

Sel suria digunakan untuk menawan foton untuk menjana tenaga. Walau bagaimanapun, penambahbaikan sel diperlukan untuk meningkatkan jumlah penangkapan foton dan juga untuk meningkatkan kecekapan sel. Ini melibatkan keseluruhan proses pembuatan sel, dengan proses penyepuhlindapan adalah salah satu daripada langkah penting yang perlu dioptimumkan. Percetakan perlogaman menggunakan dwi pembakaran merupakan kaedah yang paling biasa digunakan dalam penghasilan sel suria kristal secara komersial. Aluminium (Al) digunakan pada bahagian belakang sel sebagai medan permukaan belakang dan penyambung belakang manakala perak (Ag) dicetak pada bahagian hadapan sebagai grid pemungut. Proses dwi pembakaran bagi komponen ini adalah penting dalam menentukan kecekapan sel. Oleh itu, dalam kajian ini, rawatan pembakaran telah dikaji dengan menggunakan relau tiub kuarza (QTF) dengan perubahan suhu pembakaran (700, 750, 800 and 850°C) sebagai satu percubaan untuk mendapatkan kecekapan yang tinggi serta meningkatkan kesan pemirauan persimpangan Ag. Apabila suhu meningkat, sifat elektrik sel suria dwi-muka juga turut meningkat. Kebergantungan suhu menunjukkan rintangan pirau yang tinggi disebabkan oleh proses penyejukan yang pantas selepas proses pembakaran dan seterusnya membawa kepada faktor isi dan kecekapan sel yang tinggi

Peningkatan kecekapan pemisahan air menggunakan g-C3N4 yang disinar gama

Dalam kajian ini, kesan sinar gama ke atas bahan semikonduktor g-C3N4 kGy (0.1 kGy dan 0.5) dibincangkan dan dibandingkan dengan sampel yang tidak disinar untuk melihat perbezaanya. Bahan g-C3N4 disintesis dari urea melalui proses pempolimeran haba pada suhu 520°C. Struktur dan morfologi g-C3N4 dianalisis dengan menggunakan pembelauan Sinar- X (XRD), spektroskopi transformasi Fourier inframerah (FT-IR), mikroskop pengimbas elektron pancaran medan dengan spektroskopi tenaga sinar-X (FESEM-EDX), spektroskopi cahaya nampak - ultraungu (UV-Vis) dan ketumpatan arus (LSV). Sinar gama telah mengubah struktur ikatan g-C3N4 dan mengurangkan sela jalur iaitu daripada 2.80 eV kepada 2.72 eV. Di samping itu, sampel g-C3N4 yang disinar pada 0.1 kGy menghasilkan prestasi lima kali ganda lebih tinggi iaitu daripada 3.59 μAcm-2 kepada 14.2 μAcm-2 pada 1.23 V lawan Ag/AgCl dalam larutan elektrolit 0.5 M Na2SO4 (pH7). Kesimpulannya, keputusan kajian menunjukkan bahan semikonduktor yang dirawat dengan sinar gama berpotensi untuk meningkatkan fotoelektrokimia (PEC) pemisahan air