The interaction of CD-based chalcogenide quantum dots with raw photosynthetic pigments

Abstract

The detrimental effects of global warming caused by usage of fossil fuels and toxic gas emission to the atmosphere could be dramatically decreased by environmental sustainability and renewable energy resources. Moreover, coal, oil and gas classified as fossil fuels which almost the whole energy of the world derived from is going to respectively be over in 107, 35 and 37 years. That is why alternative renewable energy sources are quite important according to scientists. It is possible to utilise renewable energy resources in almost all areas where fossil fuels have a usage. Renewable energy is able to be used in the production of electricity, in transportation and logistics as a fuel, in buildings and industrial processes as a heat release after conversion. Wind, flowing water, sunlight, the internal heat of the earth and biomass are natural resources of renewable energy. Biomass is a significant renewable energy source because of its economic potential, easiness in production and functional usage in many areas. Biomass is defined as organic materials in total produced by a living organism like plants and animals in a stated time and place in the world. Biomass could be manufactured by almost all organic materials we know such as seed waste, wood, wastewater, paper waste, straw and manure. These days, better half of biomass production is produced by products of agriculture which are known as energy crops. That makes photosynthesis that underlies formation of food and fibre along with biomass-based biofuels quite an important process. Photosynthesis and the energy conversion required for the production of biomass are utterly related to each other. In this thesis, quantum dots having three various structures were interacted with photosynthetic pigments which are responsible for light harvesting to increase and simplify biomes production by enhancing the efficacy of photosynthesis. In addition, photosynthetic pigments were extracted by spinach leaves that are easily provided and they are kept intact during the interactions. The compositions of quantum dots' structures were designated in accordance with the absorption wavelengths of photosynthetic pigments. The quantum dots interacted were oleic acid-capped CdSSe QDs, CdSTe QDs with the Te-riched core and CdSTe QDs with the outer S-enriched region. Also, all quantum dots were synthesis two-phase synthesis method which is one of the bottom-up approaches. The CdSSe QDs were synthesised as they have an emission in the same UV range in electromagnetic spectrum that photosynthetic pigments absorb light. The CdSTe QDs with the Te-riched core have a stated composition owing to the same reason and emission spectrum in the near IR region that pigments have also absorption. The CdSTe QDs with the outer S-enriched region have no emission of light in any common region with photosynthetic pigments that absorb radiation. Those quantum dots are synthesised to examine the quantum dot-photosynthetic pigment interaction when there is no possibility of energy transfer. The results of the interactions were analysed by UV-Visible Spectrophotometer and Fluorescence Spectroscopy and experimental data was exhibited in the section of Results & Discussion in detail. As a result of all experiments, the absorption intensity of the photosynthetic pigments interacted with the Te-enriched CdSTe QDs was increased by 50% at the excitation wavelength of 410 nm. Additionally, the light harvesting capacity of photosynthetic pigments was enhanced at 500-575 nm in the green-light range of spectrum in the presence of the CdSTe QDs with the Te-riched core.