Electrodeposition an advanced thin film deposition method originally used for decorative purposes and now widely used in industrial applications such as electronics, phonics, magnetic recording and protective coatings, has also been used for the production of size and structure-controlled nanoparticles. In this research, the electrodeposition of silver (Ag) films on gold (Au) substrates with two plant (Ocimum gratissimum (Og) and Vernonia amygdalina (Va) leaf extracts as additives was explored . The effect of these leaf extracts immediately after addition and after a prolonged exposure in the electrolyte on the silver deposits was studied using cyclic voltammetry (CV), chronoamperometry (CA) and linear sweep voltammetry (LSV).  Silver thin films were electrodeposited on gold film from an electrolyte of 5 mM AgNO3  and later 5 mM AgNO3 +0.1 M KNO3 for 10 minutes, using a double potential step protocol and potentials -0.15 V and -0.3 V with and without the  plant leaf extracts. As silver was grown on the gold substrate, silver nanoparticles were also discovered to have been formed in the electrolyte. Though the deposition potential in the presence of the plant leaf extracts affected the kinetics of the silver deposition on the gold substrate, it only slightly affected the silver film thickness on the gold.   CV graphs with the plant leaf extracts show lower current densities indicating a slowing down of the deposition/dissolution rates of silver probably due to the adsorption of the leaf extracts on the surface of the growing silver films which may have affected the transport of silver ions (Ag+) towards the electrode and impacted on the silver deposition/dissolution kinetics. The deposited silver film thickness was 7 nm to 8 nm with the Og leaf extract and 1.5 nm to 2 nm with the Va leaf extract. Atomic Force microscope (AFM) was used for viewing the silver films and the mean grain sizes of the Og silver films was calculated to be . This was larger than those of the Va silver films calculated to be While the Va silver films surface roughness was higher at 10.6 , that of the Og silver film was 9.3.

Zinc oxide nanoparticles biosynthesized using two concentrations of Ocimum gratissimum (Og) plant leaf extracts were annealed at two different temperatures. Their UV-Vis absorbance peaks at 372 nm - 375 nm indicate a blue shift in excitonic absorption and their optical energy band gap values were in the range 3.22 eV – 3.31 eV. SEM images show the nanoparticles to be polydispersed and of a wide range of sizes with smaller nanoparticles clustering around bigger micrometer- sized ones with sharp edges. An annealing temperature of 400 resulted in the sintering of the nanoparticles but nanoparticles annealed at 250 had porous surfaces suggesting a possible use in gas sensor applications. XRD patterns show that the ZnO nanoparticles have the hexagonal wurtzite structure and are of good crystalline structure. Obtained crystallite sizes increased with annealing temperature and were in the range 14 nm to 29 nm. FTIR spectra show phenols, amines and aldehydes as the available reducing agents involved in the nanoparticle synthesis. The photoluminescence (PL) spectra show two emission peaks: a UV emission peak at 369 -381 nm indicating that the zinc oxide nanoparticles exhibited band-edge photoluminescence and a green emission peak at 523 nm – 538 nm suggesting the presence of defects from singly ionized oxygen vacancies. The PL peak intensities were dependent on the annealing temperatures with the UV- emission peaks for higher annealing temperatures exhibiting a spectral shift towards lower wavelengths. Plant leaf extracts concentration and the annealing temperatures used affect the structure and optical properties of the synthesized ZnO nanoparticles.

Perovskite solar cells (PSCs) made with metal halide are affordable and can give better efficiency values than older versions but their low efficiency values is still a concern.  Two Perovskite solar cells were fabricated and one had Multi wall Carbon nanotube (MWCNT) in its design. The effect of the Multi-wall Carbon nanotube (MWCNT) on their performance and power conversion were studied. MWCNT and m-TiO2 materials were characterised using UV-vis spectroscopy and their optical energy band gap  values were obtained. The TiO2 showed a prominent peak at 319 nm with absorbance 0.5 and its optical energy bandgap  of 2.59 eV falls in the visible region showing it is a clean energy source with implications for solar energy conversion. The MWCNT has  2.19 eV and showed multiple peaks. A prominent peak at 329 nm with absorbance 0.6 which was blue shifted and a peak at 517 nm with absorbance 0.3 was red-shifted. The PSC with the MWCNT in the light had a fill factor of 0.53 but 0.47 was obtained for the PSC without the MWCNT.  The PSC with MWCNT had power conversion efficiency (PCE) of 40.1 % in the dark, a value which was 2.7 % higher than the PCE of 37.4 % obtained for the same cell in light. Furthermore, the PSC without the MWCNT in the dark had a fill factor of 0.87 while the PSC with MWCNT in the dark had a fill factor was 0.51. The PSC with MWCNT had better power conversion efficiency when in the dark than in light.

X-ray fluorescence provides a powerful means of non-destructively determining the elemental composition of a sample. X-rays from a Molybdenum (Mo) source was fired on copper, molybdenum, lead, steel and brass samples to determine their composition and relative abundance of their constituent elements. Two different detectors:  the Cadmium Telluride (CdTe) and Silicon(Si) detectors were used to pick up the signals from the scattering of the X-rays at the sample surfaces and their energy resolutions as well as efficiencies were compared. With a non-noisy amplifier, the Si detector had a higher resolution (0.27 % ) when compared to the 0.38 % for the CdTe detector but it had a lower efficiency when compared to that of the CdTe detector. It was also discovered that higher energies produced lower detector efficiencies.