Time optimized cobalt-doped zinc selenide thin films have been successfully electrodeposited on fluorine-doped tin oxide substrates. The films were deposited at the varying time of 1 min, 3 mins, and 5 mins respectively. Film thickness, optical, structural, electrical, and morphological properties of the deposited thin films were evaluated. Film thickness estimated using the gravimetric method increased from 294.35 nm to 399.62 nm as deposition time increased. Optical properties showed that the absorbance of the films ranged from 13.58% to 83.15% and was found to increase as deposition time increased. Transmittance ranged from 24.40% to 73.15% and was found to decrease as deposition time increased. The reflectance of the films was found to be low while the energy band gap ranged between 2.10 eV and 2.85 eV. Structural properties confirmed the deposition of ZnSe thin film with crystallite size values that fall between 14.68 nm and 18.60 nm. Dislocation density is ranged from 4.66 × 1015 lines/m2 to 2.97 × 1015 lines/m2 while microstrain ranged between 8.53 × 10-3 and 5.83 × 10-3. Crystallite sizes of the films were found to increase as deposition time increased while dislocation density and microstrain were found to decrease as deposition time increased. Electrical properties showed that the deposited films are semiconducting films with electrical resistivity values of 1.54 × 105 Ω cm-1.83 × 104 Ω cm and electrical conductivity values of 6.30 × 10-6 S/cm-5.47 × 10-5 S/cm. The micrograph of the films showed that the films were made up of nanoparticles and nanofibres of different dimensions. Energy-Dispersive X-Ray Spectroscopy (EDS) spectra of the films confirmed the presence of cobalt, zinc, and selenium.

Semiconductor thin films of CuMnS have been deposited onto conductive fluorine-doped tin oxide (FTO) glass substrate using an electrodeposition method to investigate their properties for possible applications. Copper sulfate, manganese sulfate and Thiourea were precursors used for sources of copper, manganese and sulphur ions respectively. The concentration of manganese ions was varied while keeping deposition voltage and time constant at 0.6 and 100 s, respectively. The films were characterized for optical, structural and morphological properties. The results obtained showed that the absorbance of the films is high in the visible (VIS) and near-infrared (NIR) regions but decreases towards NIR. The films transmittance is low in the VIS but increased in the NIR regions. The extinction coefficient is low in the VIS and NIR regions and decreases as concentration of manganese ion increased. The refractive index is high and initially increased slightly from 4.49 to 4.68 in the mid-VIS region while manganese concentration increased from 0.05 to 0.15 M and then decreased to the value of 2.73 as concentration of manganese ion increased further. The optical conductivity is high throughout the VIS and NIR regions while the optical bandgap energy is in the range of 1.5 to 2.05 eV and increases as manganese ion concentration increased. The XRD analysis showed that the deposited thin films of CuMnS are crystalline with average crystallite size and micro-strain in the range of 15.86 - 24. 45 nm and 3.97×10–3 - 6.13×10–3, respectively. The SEM results showed that the films are composed of particle sizes that are spherical in shape, uniform in sizes and densely packed together and consequently make the film surface rough. These properties exhibited by the films make them good materials for applications in photovoltaic calls, solar control coatings, photothermal applications and many other electronic devices that require high temperatures. HIGHLIGHTS This paper focused on the study of the effect of manganese ion concentration on the chalcogenide semiconductor thin films of CuMnS for possible device applications Electrodeposition method was used to fabricate the semiconductor thin films of CuMnS Optical, Structural and morphological properties of the thin films were characterized The deposited thin films of CuMnS were found to have good applications for photovoltaic cells and other optoelectronic device fabrications GRAPHICAL ABSTRACT

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The properties of PbMnS semiconductor thin films deposited on fluorine-doped tin oxide (FTO) substrate using an electrodeposition method are investigated to determine their possible device applications. Lead acetate, manganese sulfate, and thiourea were used as precursors for sources of lead, manganese, and sulfur ions respectively. The concentration of lead, manganese, and sulfur ions sources with deposition voltage of 1.8 V was kept constant. The films were deposited using three electrodes system of electrodeposition method by varying deposition time. The films were characterized for optical, structural, morphological, and compositional properties and results showed that the absorbance, refractive index, and optical conductivity of the films are high in the visible (VIS) and near-infrared (NIR) regions but decreases in the NIR. These three properties initially increased with an increase in deposition time up to a time of 70 s which has the highest values of these properties before decreasing to lower values. The transmittance and extinction coefficient of the films are low in both VIS and NIR regions. The bandgap energy of PbS was found to be blue shifted with values of 1.51 eV, 1.54 eV, 1.60 eV, 1.45 eV, and 1.35 eV for the films deposited at 30 s, 50 s, 70 s, 90 s, and 110 s respectively. XRD analysis showed that the films are crystalline with sharp peaks positions indexable to crystalline planes of (111), (200), (211), (220), (311) and (400) with average crystallite size in the range of 16.110 nm to 17.218 nm. Energy-dispersive X-ray spectroscopy (EDX) results showed that the films are composed of lead, manganese, and sulfur but there are some impurity elements present mostly as a result of the substrate used. These properties exhibited by the deposited thin films of PbMnS showed that they can be used for many optoelectronic applications such as photovoltaic cells, sensors, photoconductors, etc.

Undoped and cobalt doped copper selenide thin films have been successfully prepared unto fluorine tin oxide (FTO) substrates by electrodeposition method using copper acetate, cobalt nitrate and selenium (IV) oxide as precursors for copper, cobalt and selenium ions respectively. Deposited thin films were subjected to optical, structural, morphological, compositional and electrical analysis using spectrophotometer, x-ray diffractometer, scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS) and 4-point probe. Optical results observed between the wavelength range of 300 nm and 1,000 nm showed that the films have good optical responses. Absorbance values ranged between 0.1 and 0.81 while transmittance lies between 15.59 and 78.68 %. Energy band gap of the films was found to vary from 2.10 to 2.28 eV. These results showed that cobalt as a dopant could be used to modify properties of copper selenide thin films. Structural analysis showed that the deposited films are polycrystalline in nature with hexagonal structural phase. Crystallite sizes of range 27.56 to 34.27 nm were obtained while dislocation density lied between  and . Microstrain ranged between and . Micrograph images showed flake-like particles that increased in size as percentage of cobalt increased. Energy dispersive spectroscope (EDS) results confirmed the incorporation of cobalt on the deposited copper selenide films. Electrical resistivity of the films increased from  to  while conductivity decreased from  to  as a result of variation in cobalt ion concentration. These properties of the deposited thin films positioned them for solar cell and optoelectronics device applications. HIGHLIGHTS Energy band gap of electrosynthesized cobalt doped copper selenide ranged from 2.10 to 2.28 eV Film thickness values ranged from 48.41 and 176.79 nm. Thickness values of the films were found to increase as concentration of cobalt increase Increase in dopant concentration resulted to shift in diffraction peaks towards larger angles Increase in crystallite size from 27.56 - 34.27 nm was observed as dopant concentration increases SEM images of the films revealed flake - like particles of different sizes GRAPHICAL ABSTRACT

This research presents the estimation of the hydropower potential of River Otamiri through the hydrological analysis of the elements of climate as it affects its catchment area (section passing through the Federal University of Technology Owerri). The study involves the estimation of maximum design floods for the watershed using the Gumbels Probability Distribution Method for various return periods (T r ) with the development of unit hydrograph, storm hydrograph, runoff hydrograph and flood duration curve for the catchment area of the river. In addition watershed parameters like peak flow (Q p ), lag time (T l ), time of concentration (T c ) and rainfall intensity (I c ) were determined using the soil conservation service method and other empirical formulas. In order to determine the available flow for power generation, the stage/head of the river was estimated from records provided by the River Basin Development Authority (R.B.D.A) and flow duration analyses were carried out. The analysis revealed that for time flows of 50, 75 and 100% the following energy values were obtained 34.5 MW, 11.3 MW and 1.5 MW, respectively.

Aim: The study examined the effect of time on amount of voltage generated in a foot beat electricity generating system stored in a battery. Study Design: A system made of piezoelectric materials was designed such that the foot beats of dancers on a platform would cause a mechanical deformation that would lead to conversion of mechanical energy due to pressure from the foot beats to electrical energy; and can be stored in a rechargeable lead acid battery for future use. Place and Duration of Study: Awka Anambra State, Nigeria, between November 2018 and April 2020. Methodology: A sheet of plywood measuring 300 mm x 300 mm x 3 mm thick was placed on a hard wooden board of 300 mm x 300 mm x 25 mm thick where twelve piezoelectric sensors were connected in series with foam spring inserted as separators and to aid in returning after deformation. As the dancers step on the platform, multimeter was used to take the voltage and current readings, while Lead acid rechargeable battery could be connected at the output point to store energy generated in the system and or Light Emitting Diodes (LED) and Universal Serial Bus (USB) outputs. A stop clock was also used to take the time. Results: The study revealed that it would require 901 seconds for a 50kg dancer to increase a unit voltage state of charge in a battery. It also found that it would require 749 seconds for a 60 kg dancer; and 595 seconds for an 80kg dancer respectively to increase the same 1-unit voltage state of charge in a battery. The study showed that the voltage in the battery would continue to increase until the battery is fully charged at which point it is expected that there would no longer be any increase in charge in the battery irrespective of increase in the number of foot beats or time. Conclusion: The result implies that the charge in battery caused by pressure from the foot beats is subject to the maximum voltage capacity of the battery in the system. Likewise, the amount of time and number of foot beats required to add a unit voltage state of charge in a battery in the system is subject to the applied pressure from the foot beats. In view of this, the study craves for popularisation of this technology through large scale research supported by government, corporate organisations or international organisations and institutions that will support new products development in the building and construction industry as it is the case in India and other developed countries.

Aims: This study analysed and compared the amount of voltage, current and power generated in a piezoelectric system from human foot beats. Study Design: The study was an experimental study which made use of piezoelectric materials together with human loads (weights) from the foot beats of dancers in a dance club, and connected to a rechargeable battery and multimeter. In this system, mechanical deformation was expected to cause conversion of mechanical energy to electrical energy which can be stored in a rechargeable lead acid battery for future use. Place and Duration of Study: Awka Anambra State, Nigeria, between November 2018 and February 2020. Methodology: A sheet of plywood measuring 300 mm x 300 mm x 3 mm thick was placed on a hard wooden board of 300 mm x 300 mm x 25 mm thickwhere twelve piezoelectric sensors were connected in series with foam spring inserted as separators and to aid in returning after deformation. As the dancers step on the platform, multimetr was used to take the voltage and current readings while at the output point Lead acid rechargeable battery could be connected at the output point to store energy generated in the system and orLight Emitting Diodes (LED) and Universal Serial Bus (USB) outputs. Results: The result revealed that the amount of voltage, current and power generated in the system were principally dependent on the load (weight of dancers in kg). In this case, 1 foot beat of an average 50 kg dancer generated an average of 0.555 mV and 0.063 mA respectively. Whereas, 60 kg and 80 kg dancers generated 0.668 mV and 0.838 mV respectively, and 0.081 mA and 0.087 mA respectively. It further showed that at constant number of foot beats, the amount of voltage, current and power increases as the weight of dancer increases and the lesser the weight the more number of foot beats required to generate the same quantity of electricity. In this case, 100 foot beats of a 50 kg, 60 kg and 80 kg dancer generated 55.5 mV, 66.8 mV, and 84,1 mV of voltage; 6.3 mA, 8.2 mA, and 8.8 mA of current and 349.65 mW, 544.42 mW and 740.08 mW of power respectively. Conclusion: Implicitly, this system has the potential of alleviating the problem of electricity supply and meeting of vision 2030 Sustainable Development Goals for electricity mix in Nigeria. However, it is mostly required where there are high volumes of human traffic and places that consume minimal amount of electricity, since it usually generates very small amount of energy. In view of this, there is need for a more robust research in this area and increase genuine interest in alternative and sustainable energy research by the Nigerian government.