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Enhancement of Power Conversion Efficiency with Zinc Oxide as Photoanode and Cyanococcus, Punica granatum L., and Vitis vinifera as Natural Fruit Dyes for Dye-Sensitized Solar Cells

2022-11-01 , Ili Salwani Mohamad , Mohd Natashah Norizan , Norsuria Mahmed , Jamalullail N. , Dewi Suriyani Che Halin , Mohd Arif Anuar Mohd Salleh , Sandu A.V. , Baltatu M.S. , Vizureanu P.

Ruthenium N719 is a well-known material used as the dye in commercial dye-sensitized solar cell (DSSC) devices. However, it poses risks to human health and the environment over time. On the other hand, titanium dioxide (TiO2) has low electron mobility and high recombination losses when used as a photoanode in this photovoltaic technology device. In addition, using Ruthenium as the dye material harms the environment and human health. As an alternative sensitizer to compensate Ruthenium on two different photoanodes (TiO2 and ZnO), we constructed DSSC devices in this study using three different natural dyes (blueberry, pomegranate, and black grape). In good agreement with the anthocyanin content in the fruits, black grape, with the highest anthocyanin content (450.3 mg/L) compared to other fruit dyes (blueberry—386.6 mg/L and pomegranate—450.3 mg/L), resulted in the highest energy conversion efficiency (3.63%) for the natural dye-based DSSC. Furthermore, this research proved that the electrical performance of natural dye sensitizer in DSSC applications with a ZnO photoanode is better than using hazardous Ru N719 dye with a TiO2 photoanode owing to the advantage of high electron mobility in ZnO.

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Alkaline-Activation Technique to Produce Low-Temperature Sintering Activated-HAp Ceramic

2023-02-01 , Wan Mohd Arif W Ibrahim , Mohd. Mustafa Al Bakri Abdullah , Jamil N.H. , Mohamad H. , Mohd Arif Anuar Mohd Salleh , Sandu A.V. , Vizureanu P. , Baltatu M.S. , Sukmak P.

The fabrication of hydroxyapatite (HAp) ceramics prepared by existing conventional sintering requires high-temperature sintering of 1250 °C to 1300 °C. In this paper, the activated metakaolin (MK)/HAp specimens were prepared from varied mix design inputs, which were varied solid mixtures (different amounts of MK loading in HAp) and liquid-to-solid (L/S) ratios, before being pressed and sintered at 900 °C. Phase analysis, thermal analysis, surface morphology, and tensile strength of the specimens were investigated to study the influences of the Al, Si, Fe, Na, and K composition on the formation of the hydroxyapatite phase and its tensile strength. XRD analysis results show the formation of different phases was obtained from the different mix design inputs HAp (hexagonal and monoclinic), calcium phosphate, sodium calcium phosphate silicate and calcium hydrogen phosphate hydrate. Interestingly, the specimen with the addition of 30 g MK prepared at a 1.25 L/S ratio showed the formation of a monoclinic hydroxyapatite phase, resulting in the highest diametrical tensile strength of 12.52 MPa. Moreover, the increment in the MK amount in the specimens promotes better densification when sintered at 900 °C, which was highlighted in the microstructure study. This may be attributed to the Fe2O3, Na2O, and K2O contents in the MK and alkaline activator, which acted as a self-fluxing agent and contributed to the lower sintering temperature. Therefore, the research revealed that the addition of MK in the activated-HAp system could achieve a stable hydroxyapatite phase and better tensile strength at a low sintering temperature.

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Microstructural Study on Ag/TiO2 Thin Film

2022-07-01 , Kamrosni Abdul Razak , Dewi Suriyani Che Halin , Azliza Azani , Mohd. Mustafa Al Bakri Abdullah , Mohd Arif Anuar Mohd Salleh , Norsuria Mahmed , Chobpattana V. , Kaczmarek L. , Sandu A.V. , Garus S.

The synthesis of Ag/TiO2 thin film was carried out by the sol–gel spin coating method using ITO glass as a substrate in a short period of stirring time, which is less than 25 min. The produced films were annealed in a furnace at 500◦C for 1 h. Various concentrations of AgNO3, from 0.1 to 0.9 M, were added. The as-prepared films were characterized using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results indicate that all films showed a single phase of anatase, TiO2. Ag/TiO2 thin films with 0.1 M of AgNO3 solution show that the elements form networks connecting Ag/TiO2 microstructures forming a porous, consistent, and continuous layer on the substrate surface.

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Mechanical Performance, Microstructure, and Porosity Evolution of Fly Ash Geopolymer after Ten Years of Curing Age

2023-02-01 , Aziz I.H.A. , Mohd. Mustafa Al Bakri Abdullah , Rafiza Abd Razak , Zarina Yahya , Mohd Arif Anuar Mohd Salleh , Chaiprapa J. , Rojviriya C. , Vizureanu P. , Sandu A.V. , Muhammad Faheem Mohd. Tahir , Alida Abdullah , Liyana Jamaludin

This paper elucidates the mechanical performance, microstructure, and porosity evolution of fly ash geopolymer after 10 years of curing age. Given their wide range of applications, understanding the microstructure of geopolymers is critical for their long-term use. The outcome of fly ash geopolymer on mechanical performance and microstructural characteristics was compared between 28 days of curing (FA28D) and after 10 years of curing age (FA10Y) at similar mixing designs. The results of this work reveal that the FA10Y has a beneficial effect on strength development and denser microstructure compared to FA28D. The total porosity of FA10Y was also lower than FA28D due to the anorthite formation resulting in the compacted matrix. After 10 years of curing age, the 3D pore distribution showed a considerable decrease in the range of 5–30 µm with the formation of isolated and intergranular holes.

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Strength development and elemental distribution of dolomite/fly ash geopolymer composite under elevated temperature

2020-02-01 , Azimi E.A. , Mohd. Mustafa Al Bakri Abdullah , Vizureanu P. , Mohd Arif Anuar Mohd Salleh , Sandu A.V. , Chaiprapa J. , Yoriya S. , Kamarudin Hussin , Aziz I.H.

A geopolymer has been reckoned as a rising technology with huge potential for application across the globe. Dolomite refers to a material that can be used raw in producing geopolymers. Nevertheless, dolomite has slow strength development due to its low reactivity as a geopolymer. In this study, dolomite/fly ash (DFA) geopolymer composites were produced with dolomite, fly ash, sodium hydroxide, and liquid sodium silicate. A compression test was carried out on DFA geopolymers to determine the strength of the composite, while a synchrotron Micro-Xray Fluorescence (Micro-XRF) test was performed to assess the elemental distribution in the geopolymer composite. The temperature applied in this study generated promising properties of DFA geopolymers, especially in strength, which displayed increments up to 74.48 MPa as the optimum value. Heat seemed to enhance the strength development of DFA geopolymer composites. The elemental distribution analysis revealed exceptional outcomes for the composites, particularly exposure up to 400°C, which signified the homogeneity of the DFA composites. Temperatures exceeding 400°C accelerated the strength development, thus increasing the strength of the DFA composites. This appears to be unique because the strength of ordinary Portland Cement (OPC) and other geopolymers composed of other raw materials is typically either maintained or decreases due to increased heat.

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Microstructural Study on Ag/TiO2 Thin Film

2022-07-01 , Razak K.A. , Dewi Suriyani Che Halin , Azani A. , Mohd. Mustafa Al Bakri Abdullah , Mohd Arif Anuar Mohd Salleh , Mahmed N. , Chobpattana V. , Kaczmarek L. , Sandu A.V. , Garus S.

The synthesis of Ag/TiO2 thin film was carried out by the sol–gel spin coating method using ITO glass as a substrate in a short period of stirring time, which is less than 25 min. The produced films were annealed in a furnace at 500◦C for 1 h. Various concentrations of AgNO3, from 0.1 to 0.9 M, were added. The as-prepared films were characterized using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results indicate that all films showed a single phase of anatase, TiO2. Ag/TiO2 thin films with 0.1 M of AgNO3 solution show that the elements form networks connecting Ag/TiO2 microstructures forming a porous, consistent, and continuous layer on the substrate surface.

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Enhancement of Power Conversion Efficiency with Zinc Oxide as Photoanode and Cyanococcus, Punica granatum L., and Vitis vinifera as Natural Fruit Dyes for Dye-Sensitized Solar Cells

2022-11-01 , Ili Salwani Mohamad , Mohd Natashah Norizan , Norsuria Mahmed , Nurnaeimah Jamalullail , Dewi Suriyani Che Halin , Mohd Arif Anuar Mohd Salleh , Sandu A.V. , Baltatu M.S. , Vizureanu P.

Ruthenium N719 is a well-known material used as the dye in commercial dye-sensitized solar cell (DSSC) devices. However, it poses risks to human health and the environment over time. On the other hand, titanium dioxide (TiO2) has low electron mobility and high recombination losses when used as a photoanode in this photovoltaic technology device. In addition, using Ruthenium as the dye material harms the environment and human health. As an alternative sensitizer to compensate Ruthenium on two different photoanodes (TiO2 and ZnO), we constructed DSSC devices in this study using three different natural dyes (blueberry, pomegranate, and black grape). In good agreement with the anthocyanin content in the fruits, black grape, with the highest anthocyanin content (450.3 mg/L) compared to other fruit dyes (blueberry—386.6 mg/L and pomegranate—450.3 mg/L), resulted in the highest energy conversion efficiency (3.63%) for the natural dye-based DSSC. Furthermore, this research proved that the electrical performance of natural dye sensitizer in DSSC applications with a ZnO photoanode is better than using hazardous Ru N719 dye with a TiO2 photoanode owing to the advantage of high electron mobility in ZnO.

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Recent Developments in Steelmaking Industry and Potential Alkali Activated Based Steel Waste: A Comprehensive Review

2022-03-01 , Ikmal Hakem Aziz , Mohd. Mustafa Al Bakri Abdullah , Mohd Arif Anuar Mohd Salleh , Liew Yun Ming , Li L.Y. , Sandu A.V. , Vizureanu P. , Nemes O. , Mahdi S.N.

The steel industry is responsible for one-third of all global industrial CO2 emissions, putting pressure on the industry to shift forward towards more environmentally friendly production methods. The metallurgical industry is under enormous pressure to reduce CO2 emissions as a result of growing environmental concerns about global warming. The reduction in CO2 emissions is normally fulfilled by recycling steel waste into alkali-activated cement. Numerous types of steel waste have been produced via three main production routes, including blast furnace, electric arc furnace, and basic oxygen furnace. To date, all of the steel waste has been incorporated into alkali activation system to enhance the properties. This review focuses on the current developments over the last ten years in the steelmaking industry. This work also summarizes the utilization of steel waste for improving cement properties through an alkali activation system. Finally, this work presents some future research opportunities with regard to the potential of steel waste to be utilized as an alkali-activated material.

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Controlling the Layer Thickness of Zinc Oxide Photoanode and the Dye-Soaking Time for an Optimal-Efficiency Dye-Sensitized Solar Cell

2023-01-01 , Magiswaran K. , Mohd Natashah Norizan , Norsuria Mahmed , Ili Salwani Mohamad , Idris S.N. , Sabri M.F.M. , Amin N. , Sandu A.V. , Vizureanu P. , Nabiałek M. , Mohd Arif Anuar Mohd Salleh

Dye-sensitized solar cells (DSSCs) were developed by exploiting the photovoltaic effect to convert solar energy into electrical energy. The photoanode layer thickness significantly affects the semiconductor film’s ability to carry electronic charges, adsorb sensitizing dye molecules, and lower the recombination of photo-excited electrons injected into the semiconductor. This study investigated the dependence of the zinc oxide (ZnO) photoanode thin-film thickness and the film soaking time in N719 dye on the photocurrent–voltage characteristics. The ZnO photoanode was applied to glass using the doctor blade method. The thickness was varied by changing the scotch tape layers. The ZnO-based DSSC attained an efficiency of 2.77% with three-layered photoanodes soaked in the dye for three hours, compared to a maximum efficiency of 0.68% that was achieved with three cycles using the dip-coating method in other research. The layer thickness of the ZnO photoanode and its optimal adsorption time for the dye are important parameters that determine the efficiency of the DSSC. Therefore, this work provides important insights to further improve the performance of DSSCs.

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Synthesis of Zn/TiO2 Thin Films for Self-Cleaning Applications

2022-07-01 , Dewi Suriyani Che Halin , Abidin A.S.Z. , Azani A. , Mohd Arif Anuar Mohd Salleh , Kamrosni Abdul Razak , Mohd. Mustafa Al Bakri Abdullah , Muhammad Mahyiddin Ramli , Sandu A.V. , Vizureanu P. , Kaczmarek L. , Garus S. , Garus J.

Titanium dioxide (TiO2) thin film has been widely used in semiconductor applications. The surface modification on TiO2 has been done by adding zinc (Zn) in order to improve surface wettability and enhance the photocatalysis efficiency for solar cell applications. Self-cleaning technology is very important to sustain the efficiency of the solar cell and reduce the cost of the maintenance of the solar cell. In this work, the sol–gel method was used due to the economic factor and its best efficiency. The sol–gel method is a wet chemical technique involving several steps, such as hydrolysis and polycondensation, gelation, aging, drying, densification, and crystallization. The X-Ray diffraction pattern shows that anatase and rutile phases were detected at 2θ = 36.3864◦. It was clearly seen at 4% Zn-doped TiO2 annealed at 400◦C that due to the increment of Zn concentration, the phase transformed from the anatase phase to the rutile phase at high temperature. The scanning electron microscope micrograph shows that Zn concentration affects grain size. The water contact angle produced when 4% Zn-doped TiO2 was annealed at 300◦C, was 18◦ — higher than in the sample of 4% Zn-doped TiO2 annealed at 400◦C. These results clearly showed that the dopant concentration and the annealing temperature influence the properties of TiO2 for a self-cleaning application.