School of Pure, Applied and Sciences (JA)

Study about TiO2/Nb2O5 Composite Electrode Thin Films for Photovoltaic Applications

2025-01-01T00:00:00Z

Study about TiO2/Nb2O5 Composite Electrode Thin Films for Photovoltaic Applications Nguu, John Njagi; Aduda, Bernard Odhiambo; Nyongesa, Francis Wanjala; Musembi, Robinson Juma Nanopowders can be defined as powdered materials with individual particles in nanometer scale or materials with crystalline in nanometer scale. Nanoparticles (NPs) are made up of a large amount of atoms or molecules bonded with each other with a total size varying from 1 nm to around 100 nm. Due to their very small sizes, NPs possess an extraordinarily high surface area-to-volume ratio, which changes their physical-chemical properties compared to their macroscale counterparts. Nano sized powders of TiO2 (titanium dioxide) and Nb2O5 (Niobium (V) oxide) were used to fabricate TiO2/Nb2O5 composites thin films by EPD (electrophoretic deposition) technique. In an EPD cell, pellets of magnesium nitrate hexahydrate and metal oxide powders were suspended in propan-2-ol. 1.2 cm apart, the electrodes were submerged in the suspension with a DC potential supplied across them. Through visual examination and analysis of UV-Vis-NIR spectrophotometer spectra, key EPD process parameters, including as the applied DC electric field, deposition duration, and solid concentration in suspension, were improved. The films with deposition times of 90 s, powder concentrations of 0.01 g/40 mL, and direct current (DC) voltage of 35 V had the maximum transmittance (55%) of all the samples. XRD micrographs confirmed that TiO2 and Nb2O5 particles were presented in the composite film. SEM (scanning electron microscope) micrographs of the composite electrode thin films showed that porous films of high quality with well controlled morphology were deposited by using the EPD technique

Livestock Farmers’ Perception on Generation of Cattle Wastebased Biogas Methane: the Case of Embu West District, Kenya

2014-01-01T00:00:00Z

Livestock Farmers’ Perception on Generation of Cattle Wastebased Biogas Methane: the Case of Embu West District, Kenya Nguu, John; Ndivo, Susan; Aduda, Bernard; Nyongesa, Francis; Musembi, Robinson Perception of livestock farmers on the generation of cattle waste-based biogas methane was evaluated in this study. The study was carried out in Embu West district in Kenya. A random sampling technique was used to gather information related to farmers’ perception and the data collected with the help of self designed questionnaires and face to face interviews. In the study, 92.9% of the one hundred and fifty six (156) livestock farmers practiced zero-grazing and only fourteen (9%) of them had installed biogas digesters in their farms. Chi square tests yielded a value of χ = 0.591, p >0.05 which indicated that there was no significant relationship between uptake of cattle waste-based biogas and farmer’s perception. The hypothesis that low uptake of cattle waste-based biogas technology was due to negative perception of the farmers was found not to hold. Further Chi square tests indicated significant relationship (χ=23.56, p< 0.05) between farmers’ perception and knowledge of cattle waste-based biogas methane. Thus livestock farmers in Embu district had a very positive perception and were quite knowledgeable about biogas technology despite the minimal installation of the cattle waste-based biogas digesters. The research findings indicated that other factors like installation cost contribute to the low uptake of biogas technology. These research findings should assist government and industry understand the reason behind public ‘reservations’ in the adoption of biogas technology as well as develop strategies for enhanced promotion of renewable energy technologies

Electrophoretic Deposition of TiO2/Nb2O5 Composite Electrode Thin Films for Photovoltaic Application

2014-01-01T00:00:00Z

Electrophoretic Deposition of TiO2/Nb2O5 Composite Electrode Thin Films for Photovoltaic Application Nguu, John Njagi; Aduda, Bernard Odhiambo; Nyongesa, Francis Wanjala; Musembi, Robinson Juma Nano sized powders of TiO2 (titanium dioxide) and Nb2O5 (Niobium (V) oxide) were used to fabricate TiO2/Nb2O5 composites thin films by EPD (electrophoretic deposition) technique. The metal oxide powders, together with magnesium nitrate hexahydrate pellets, were suspended in propan-2-ol inside an EPD cell. The electrodes, placed 1.2 cm apart, were partially immersed in the suspension and a DC potential applied across them. Key EPD process parameters, which include applied DC electric field, deposition time and solid concentration in suspension, were optimized through visual inspection and from UV-Vis-NIR spectrophotometer spectra. The highest (55%) transmittance was obtained for films with deposition time of 90 s, powder concentration of 0.01 g/40 mL, and 35 V DC (direct current) voltage. XRD micrographs confirmed that TiO2 and Nb2O5 particles were presented in the composite film. SEM (scanning electron microscope) micrographs of the composite electrode thin films showed that porous films of high quality with well controlled morphology were deposited by using the EPD technique

Electrophoretic Deposition and Characterization of TiO2/Nb2O5 Composite Thin Films for Dye Sensitized Solar Cells

2018-01-01T00:00:00Z

Electrophoretic Deposition and Characterization of TiO2/Nb2O5 Composite Thin Films for Dye Sensitized Solar Cells Nguu, John; Nyongesa, Francis; Musembi, Robinson; Aduda, Bernard In this study, Electrophoretic Deposition (EPD) technique was used to fabricate TiO2/Nb2O5 composite thin films on FTO coated glass for application as photoelectrodes in Dye Sensitized Solar Cells (DSSC). A TiO2/Nb2O5 ratio of 1:1 was used in a 2-propanol suspension solution with a solid loading of 0.25g/L. Optical investigations showed that the film with thickness of 5.5 µm deposited at 35.0 V for 90.0 s had the highest transmittance of 55.0 % at a wavelength (λ) of 1,300 nm. The optical band gap energy (Eg) was 3.884 eV and was found to be dependent on the annealing time. The solar cell fabricated from this film had an open circuit voltage (VOC) of 0.66 V, fill factor (FF) of 57.0%, short current density (JSC) of 5.25 mA/cm2 and photo conversion efficiency (PCE) of 2.0%. Electrochemical Impedance Spectroscopy (EIS) analysis indicate that the DSSC device with thinner photoelectrodes have more efficient electron transport in the photoanode compared to thicker photoelectrodes to achieve higher conversion efficiencies