Synthesis Of Sn And V Based Nanostructures: Potential Materials For Optoelectronics And Energy Storage

Tin and Vanadium based nanostructured materials have engrossed an immenseconsideration owing to their distinctive physical and chemical properties. Both tin andvanadium have transition valance states which render multidimensional/multifunctionaloptoelectronic and energy storage properties thus making them distinct from other elements.The properties of nanomaterials are highly dependent on the nanostructure morphology andsurface states. In this research we have developed innovative, economical and green routesfor the synthesis of novel nanostructures by replacing tedious and toxic preparativemethods/routes. The novel nanostructures synthesized by new routes also inheritadditional/new surface states and morphologies leading to intriguing properties. This thesispresents the research work on tin and vanadium based novel nanostructured materials. Thestudy covers preparation, characterization, growth mechanism and their intriguingoptoelectronic and energy storage properties. In order to investigate the potentialapplications their optical transmission/absorption, micro Raman spectroscopy,photoluminescence, electrical properties (I-V), hydrogen absorption/desorption properties,electrochemical supercapacitor and field emission have been studied.At first, novel SnO2nanofibers bundle (NFB) have been synthesized via chemicalvapor deposition (CVD) by using ball milled Fe powders as catalyst. The microscopyanalysis reveals the existence of tubular structure that might be formed by the accumulationof nanofibers. The Raman spectrum reveals that the product is rutile SnO2with additionalpeaks ascribed to defects or oxygen vacancies. Room temperature Photoluminescence (PL)spectrum exhibits three emission bands at369,450and466.6nm. Using optical absorbancedata, a direct optical bandgap of3.68eV was calculated. The nanostructure formed by our method can be good candidate for the study of electrical devices such as UV and gassensors.Later on, large scale zigzag nanobelts were obtained on a silicon substrate by aChemical Vapor Deposition (CVD) approach. The average value of carrier concentrations(Nd) and Electron mobility () were calculated to be1.39×1018cm3and70.76cm2V-1s-1,respectively. The room temperature cathodoluminescence (CL) spectrum of single zigzagnanobelts was studied using a Renishaw Raman spectroscopy system. Room temperature PLexhibits a broad emission peak centered at600nm. Three Raman active modes at474.8,633.8,775.8cm-1were observed. Electron paramagnetic resonance measurements suggest thepresence of many singly ionized states. The electrical characteristics reveal that zigzagnanobelts could be good candidates for nanocircuits, nano-optoelectronics and sensingdevices.Afterwards, SnSe nanospheres were synthesized using a green novel route bypretreatment of precursors with aqueous ammonia. Chemical vapor deposition techniquewas used for the growth of SnSe nanostructures. To account for the potential applications ofnanosized chalcogenides for solar cells and photovoltaic devices it is important to study andinvestigate their optical properties. The optical properties were studied using UV-vis-NIRspectroscopy. UV emission shows that SnSe nanospheres could be used in practicalapplications such visible light emission devices.Next, high quality SnSe nanowires were synthesized via chemical vapour deposition(CVD) for the first time. The route is highly economical and green alternative as comparedto previous methods in literature. Only powders tin and selenium were used as precursorsunder controlled hydrogen plus argon environment. The synthesis is facile, economical andenvironmental friendly which will pave the way for future optoelectronic devices for energy harvesting and photovoltaic applications. The synthesized SnSe nanowires weresingle crystalline. The length of nanowires was in tens of microns with an average diameterof about30-40nm. Further, the optical and electrical properties reveal the potential of SnSenanowires for photovoltaic and optical devices. These studies will enable significantadvancements of the next generation photodetection and solar cell applications.Subsequently, ZnV2O4glomerulus nanospheres were synthesized via template freeroute by utilizing common laboratory reagents to expose its hydrogen storage potential.The maximum values attained for hydrogen absorption in ZnV2O4nanospheres are1.688wt.%at473K,1.887wt.%at573K and2.165wt.%at623K respectively. In order to see theinfluence of hydrogen storage on defects/vacancies, PL studies were performed for the firsttime. One weak peak appears in the UV region at373nm whereas a broad and intense peakwas observed in the visible region at429nm. Hydrogen storage measurement revealspotential of ZnV2O4nanospheres as a prospective material for energy storage applications.Next, ZnV2O4spinel oxide novel nanosheets were synthesized via a template freeroute to explore its potential hydrogen storage properties. The maximum value forhydrogen absorption in ZnV2O4nanosheets at473K is1.36wt.%and1.74wt.%at573K,respectively. Our hydrogen storage measurements along ZnV2O4reveal its superiority overprevious reports on hydrogen absorption values concerning oxides, nitrides andchalcogenides. PL measurements demonstrate the potential for violet/blue optoelectronicdevices.Later on, facile templates free method was devised to synthesize novel hierarchicalnanospheres (NHNs) of ZnV2O4. The measured specific capacitance of ZnV2O4electrode is360F/g at1A/g with good stability and retention capacity of89%after1000cycles. Moreover, the hydrogen storage properties of NHNs were measured at473K,573K and623K with an absorption of1.76wt.%,2.03wt.%and2.49wt.%, respectively. Thesestudies pave the way to consider ZnV2O4as prospective material for energy storageapplications.At the end, a facile, economical and scalable synthesis technique for fabrication ofsuper long V2O5nanobelts was presented. The calculated aspect ratio of V2O5nanobeltswas4500-4700~103. The nanobelts have an optical bandgap is2.3eV. The Ramanspectrum confirms the pure state of V2O5nanobelts. A low turn-on field of1.4Vμm1and athreshold field of2.13Vμm1are obtained for V2O5super long nanobelts. The Carrierconcentrations Nd=1.48×1018cm-3and Electron mobility=1.26cm2/Vs and conductivity=36.1S/m was calculated using MSM model.