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The safe and sound disposal of vegetable market waste (VMW) is a major concern of India today. VMW is being produced in millions of tonnes in urban areas, which are often deposited in dumpsites, left untreated, or burned in open fires. A potential remedy for these waste disposal and high fuel dependence on wood as fuel is the conversion of this biomass into high-density briquettes. This paper presents an experimental exploration of fuel properties of bio-briquettes made from a combination of VMW and sawdust (SD). In the present work, binary briquettes have been made from VMW in combination with SD in a ratio of 25, 50, 75, and 100% by weight using bentonite clay as a binder. Furthermore, a comparative study between the VMW based biomass briquettes with firewood, coal, and conventional sawdust briquettes are also included in this study. Raw green vegetable wastes were collected from markets and were kept for open sun drying. The dried matter was then transformed into a pulverized form and eventually converted to briquettes. The percentage of moisture content, percentage volatile matter content, ash content percentage, fixed carbon content, and calorific values of the briquettes were investigated. The results showed that the composite briquettes had improved combustion characteristics like higher calorific value and more volatile matter content compared with pure VMW briquettes. The percentage volatile matter content of VMW briquette enhanced from 71.72% to 83.2% for the composite briquette of VMW and SD with the highest percentage at the proportion 25:75 (VMW: SD). The calorific value of bio-briquettes ranges from 14.002 to 15.721 MJ/kg and the highest heating value was obtained for the composite briquette of VMW and SD with proportion 25:75. Even though lignin contents of vegetable market waste were lesser (3.23–5.51%) compared to other ligno-cellulosic biomass, good quality biomass briquettes were produced.

Carbon nanotubes, the one-dimensional allotropes of carbon, have attracted significant research interest ever since their discovery due to their outstanding material properties. The exceptional physical, chemical, and electronic properties of carbon nanotubes (CNTs) and their composites offer exciting possibilities for nanometer-scale electronic applications. This chapter presents an overview of the structure, properties, and applications of CNTs. Depending on their structure, CNTs can either be metallic or semiconducting. Both physical and chemical methods are used for the synthesis of CNTs. Manipulated CNTs are produced by the modification of the surface of CNTs by foreign particle decorations as well as physical treatments. The manipulation process alters the properties of CNTs. An account of the potential practical use of CNTs and their composites in electrochemical energy storage, hydrogen storage, field emission, and electrochemical sensors is given toward the end of this chapter.

We report the high temperature thermoelectric properties of solution processed untreated and sulphuric acid treated poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (or PEDOT:PSS) films. The acid treatment is shown to simultaneously enhance the electrical conductivity and the Seebeck coefficient of the metal-like films, resulting in a five-fold increase in the thermoelectric power factor (from 0.01 to 0.052 W m−1 K−1) at 460 K, compared to the untreated film. By using atomic force micrographs, Raman and impedance spectra and using a series heterogeneous model for electrical conductivity, we demonstrate that acid treatment results in the removal of PSS from the films, leading to the quenching of accumulated charge-induced energy barriers, facilitating metal-like conduction. The continuous removal of PSS and changes in morphology of the PEDOT grains upon acid treatment may alter the local band structure of PEDOT:PSS, in such a way as to simultaneously enhance the Seebeck coefficient.

Transparent thin-film thermocouples have been fabricated with indium tin oxide (ITO) and manganese doped indium tin oxide (Mn:ITO) as the positive and negative legs, respectively. Optical transparency of the thermocouples was above 85% in the visible region of the spectrum. Presence of Mn has been found to enhance the thermoelectric response, without significantly increasing the resistivity. Seebeck voltages of ~ 20 mV and ~ 31 mV have been obtained at 625 K, respectively, for the thermocouples with Mn:ITO legs having 1.6 at.% and 4.3 at.% Mn. The response has been found to be reproducible with an error of plusmn2%.

Correlation of charge state of Mn with the increase in resistivity with Mn concentration is demonstrated in Mn-doped indium tin oxide films. Bonding analysis shows that Mn 2p3/2 core level can be deconvoluted into three components corresponding to Mn2+ and Mn4+ with binding energies 640.8 eV and 642.7 eV, respectively, and a Mn2+ satellite at ?5.4 eV away from the Mn2+ peak. The presence of the satellite peak unambiguously proves that Mn exists in the +2 charge state. The ratio of concentration of Mn2+ to Mn4+ of ?4:1 suggests that charge compensation occurs in the n-type films causing the resistivity increase. � 2010 American Institute of Physics.

Thermopower measurements in a range of 300-650 K along with room temperature optical absorption and electrical resistivity studies were performed on indium oxide (IO) and indium tin oxide (ITO) thin films grown by reactive dc sputtering. The thermopower of as-grown and oxygen-annealed IO and ITO films measured in Ar ambient displayed characteristics attributable to oxygen loss. The observations were substantiated with optical absorption and electrical resistivity results. � 2009 IOP Publishing Ltd.

An experimental setup is developed for the measurement of the Seebeck coefficient of thin wires and thin films in the temperature range of 300-650 K. The setup makes use of the integral method for measuring the Seebeck voltage across the sample. Two pointed copper rods with in-built thermocouples serve as hot and cold probes as well as leads for measuring the Seebeck voltage. The setup employs localized heating and enables easy sample loading using a spring loaded mounting system and is fully automated. Test measurements are made on a constantan wire and indium tin oxide (ITO) thin film for illustration. The Seebeck voltage obtained for constantan wire is in agreement with the NIST data for copper constantan couple with an error of 1%. The calculated carrier concentration of ITO film from the Seebeck coefficient measurement is comparable with that obtained by electrical transport measurements. The error in the Seebeck coefficient is estimated to be within 3%. � 2008 American Institute of Physics.

In this letter, the formation of nanostructured graphene by ultraviolet laser ablation of a highly ordered pyrolytic graphite target under optimized conditions is demonstrated, without a catalytic layer, and a model for the growth process is proposed. Previously, graphene film deposition by low-energy laser (2.3 eV) was explained by photo-thermal models, which implied that graphene films cannot be deposited by laser energies higher than the C-C bond energy in highly ordered pyrolytic graphite (3.7 eV). Here, we show that nanostructured graphene films can in fact be deposited using ultraviolet laser (5 eV) directly over different substrates, without a catalytic layer. The formation of graphene is explained by bond-breaking assisted by photoelectronic excitation leading to formation of carbon clusters at the target and annealing out of defects at the substrate.

A detailed study of the role of oxygen vacancies in determining the effective mass and high temperature (300–1000 K) thermoelectric properties of La-doped epitaxial SrTiO3 thin films is presented. It is observed that at intermediate temperatures, a transition from degenerate to non-degenerate behavior is observed in the Seebeck coefficient, but not electrical conductivity, which is attributed to heterogeneous oxygen non-stoichiometry. Heikes formula is found to be invalid for the films with oxygen vacancies. By fitting the spectroscopic ellipsometry (SE) data, obtained in the range 300–2100 nm, using a Drude-Lorentz dispersion relation with two Lorentz oscillators, the electrical and optical properties of the films are extracted. Using the excellent agreement between the transport properties extracted from SE modeling and direct electrical measurements, we demonstrate that an increase in concentration of oxygen vacancies results in a simultaneous increase of both carrier concentration and electron effecti...

The influence of oxygen vacancies on the transport properties of epitaxial thermoelectric (Sr,La)TiO3 thin films is determined using electrical and spectroscopic ellipsometry (SE) measurements. Oxygen vacancy concentration was varied by ex-situ annealing in Ar and Ar/H2. All films exhibited degenerate semiconducting behavior, and electrical conductivity decreased (258–133 S cm−1) with increasing oxygen content. Similar decrease in the Seebeck coefficient is observed and attributed to a decrease in effective mass (7.8–3.2 me), as determined by SE. Excellent agreement between transport properties deduced from SE and direct electrical measurements suggests that SE is an effective tool for studying oxide thin film thermoelectrics.