Commercial and economic success of concentrated solar power (CSP) plants requires operating at maximum efficiency and capacity which necessitates the use of materials that are reliable at high temperatures. This study investigates the corrosion behavior of structural alloys in molten nitrate salts at three temperatures common to CSP plants. Corrosion behavior was evaluated using gravimetric and inductively-coupled plasma optical emission spectroscopy (ICP-OES) analysis. Surface oxide structure and chemistry was characterized using X-ray diffraction and Raman spectroscopy. Electrochemical behavior of candidate structural alloys Alloy 4130, austenitic stainless steel 316, and super-austenitic Incoloy 800H was evaluated using potentiodynamic polarization characteristics. Gravimetric and ICP-OES analysis indicated that Alloy 4130 exhibited the least corrosion resistance at 500 • C compared to SS316 and 800H. However, at 300 • C, the three alloys exhibited similar weight gain. Electrochemical evaluation of these candidate materials was observed to correlate well with the corrosion behavior observed from gravimetric and ICP-OES analysis. This study identifies that all three alloys exhibited acceptable corrosion rate in 300 • C molten salt, while elevated salt temperatures require the more corrosion resistant alloys, stainless steel 316 and 800H. Characterization of the sample surfaces revealed the presence of spinels at lower temperatures, while Fe 2 O 3 was the dominant iron oxide at higher temperatures for each alloy. Like all power plants, maximizing the conversion efficiency of solar energy in a concentrated solar power (CSP) plant is essential to minimizing cost and resources while maximizing energy output. The choice of heat transfer fluid is a fundamental parameter in maximizing efficiency of an energy source. A heat transfer fluid that can also function as an energy storage medium for solar energy while being chemically compatible with the structural components of the plant is an ideal candidate for implementation.Significant research had been performed from 1982 to 1985 on the use of molten salt as a heat transfer medium in solar power applications. Sandia National Laboratory in New Mexico conducted the Molten Salt Electric Experiment (MSEE) which was the first power tower system to use molten nitrate salt as the primary working fluid to produce electricity. This experiment proved the feasibility of using molten salt as a heat transfer medium in a central receiver design along with a two-tank storage system designed to address intermittency. 1The MSEE used a molten nitrate salt composition of 40% KNO 3 and 60% NaNO 3 by weight which is the composition used for the study presented herein.Corrosion of structural components is determined by the properties of the heat transfer fluid and corrosion resistance of the components in contact with that heat transfer fluid. Depending on the corrosion resistance of the alloy to a high-temperature, oxidizing environment, the alloy will either form an adherent, compact oxid...

This study reports the synthesis of Zn x Cd 1Àx Se quantum dot-sensitized titania nanotube array photoelectrodes using a successive ionic layer adsorption and reaction technique and evaluates the photoelectrochemical performance as anodes. The effect of altering the number of sensitization cycles and annealing temperature on optical and photoelectrochemical properties of prepared photoanodes was studied. Surface morphology of the sensitized tubes was analyzed by scanning electron microscopy, while the phase composition was determined using X-ray diffraction and X-ray photoelectron spectroscopy techniques. Spectral response measurements indicated that TiO 2 nanotube arrays coupled with Zn x Cd 1Àx Se quantum dots synthesized in 7 cycles of deposition and annealed at 300 C for 1 h under N 2 exhibited excellent photoelectrochemical properties. The notably high photovoltaic characteristics demonstrate the potential of the Zn x Cd 1Àx Se/TiO 2 heterostructure as an efficient photoanode.

This study demonstrates solar driven oxidation of hydrazine hydrate and the simultaneous production of hydrogen and electricity in photoelectrochemical cells and photofuel cells, respectively, using a visible light active molybdenum doped BiVO4 photoelectrode. The developed photoelectrodes exhibited tremendous efficiency towards anodic oxidation of hydrous hydrazine with continuous and stable hydrogen evolution at the Pt cathode under benign pH and zero bias conditions. Significantly, the photofuel cell containing hydrazine hydrate fuel has generated electricity with a high open circuit potential of 0.8 V. The presence of bicarbonate ions in the electrolyte has played a significant role in enhancing the kinetics of photoelectrochemical oxidation of hydrazine and improved the hydrogen and electricity generation efficiency thus avoiding the integration of an oxidation electrocatalyst. In addition, molybdenum doped BiVO4 as a possible photoelectrochemical hydrazine sensor has been investigated and the electrode photocurrent was found to be linearly dependent on the concentration of the hydrazine hydrate in the range of 20-90 mM with a correlation coefficient of 0.9936.

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