Madhivanan Muthuvel

Density Functional Theory Analysis of Raman Frequency Modes of Monoclinic Zirconium Oxide Using Gaussian Basis Sets and Isotopic Substitution

Geometry and vibration properties for monoclinic zirconium oxide were studied using Gaussian basis sets and LDA, GGA, and B3LYP functionals. Bond angles, bond lengths, lattice parameters, and Raman frequencies were calculated and compared to experimental values. Bond angles and lengths were found to agree within experimental standard deviations. The B3LYP gave the best performance of all three functionals with a percent error of 1.35% for the lattice parameters while the average difference between experimental and calculated Raman frequency values was -3 cm(-1). The B3LYP functional was then used to assign the atomic vibrations causing each frequency mode using isotopic substitution of (93.40)Zr for (91.22)Zr and (18.00)O for (16.00)O. This resulted in seven modes assigned to the Zr atom, ten modes to the O atom, and one mode being a mixture of both.

Electrochemical Energy Storage: Applications, Processes, and Trends

Energy consumption in the world has increased significantly over the past 20 years. In 2008, worldwide energy consumption was reported as 142,270 TWh [1], in contrast to 54,282 TWh in 1973; [2] this represents an increase of 262%. The surge in demand could be attributed to the growth of population and industrialization over the years. In 2009, energy consumption was reported as 140,700 TWh, a slight decrease (1.1%) when compared to 2008 due to the world financial crisis [1], while in 2010 there was a rise in the consumption to 149,469 TWh, due to the recovery of the economy at that time [3]. Conversely, the total supply of energy in the world had caught up with the consumption as shown in Table 38.1 [2, 4]. Approximately 10–14% of the total energy supply in the world is delivered as electric energy. In addition, the amount of power supplied by renewables had increased over the years, from 37 TWh in 1973 to 612 TWh in 2008 (as shown in Table 38.1), which represents a growth of 94%. However, the total amount of energy available from renewables based on current technology could reach up to 834,280 TWh (distributed as: 53.2% solar, 20.0% wind, 16.7% geothermal, 8.4% biomass, and 1.7% hydropower); [5] that is, 5.7 times the world energy supply in 2008. Nevertheless, renewable sources of energy such as solar and wind are intermittent and only abundant in certain regions, which causes a limitation on the use and distribution of such sources of energy. An undersized world energy surplus (based on a total energy balance including supply, consumption, and losses) is usually reported annually; a comprehensive analysis is presented in the literature [2].

9.14 Preparative Electrochemistry for Organic Synthesis

This chapter provides an overview of the advances in electrochemistry and electrochemical engineering that have taken place in the last few decades and discusses how these advances could be implemented in the synthesis of organic molecules from conception to the market.

Combined Theoretical and Experimental Investigation and Design of H2S Tolerant Anode for Solid Oxide Fuel Cells

A solid oxide fuel cell (SOFC) is a high temperature fuel cell and it normally operates in the range of 850 to 1000 C. Coal syngas has been considered for use in SOFC systems to produce electric power, due to its high temperature and high hydrogen and carbon monoxide content. However, coal syngas also has contaminants like carbon dioxide (CO{sub 2}) and hydrogen sulfide (H{sub 2}S). Among these contaminants, H{sub 2}S is detrimental to electrode material in SOFC. Commonly used anode material in SOFC system is nickel-yttria stabilized zirconia (Ni-YSZ). The presence of H{sub 2}S in the hydrogen stream will damage the Ni anode and hinder the performance of SOFC. In the present study, an attempt was made to understand the mechanism of anode (Ni-YSZ) deterioration by H{sub 2}S. The study used computation methods such as quantum chemistry calculations and molecular dynamics to predict the model for anode destruction by H{sub 2}S. This was done using binding energies to predict the thermodynamics and Raman spectroscopy to predict molecular vibrations and surface interactions. On the experimental side, a test stand has been built with the ability to analyze button cells at high temperature under syngas conditions.