Catalyst-free synthesis of copper oxide composites as solar radiative filters.

Copper oxide composites were successfully synthesized by a catalyst-free method, plasma arc technology. The as-synthesized composites were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. The analysis revealed a mixture of crystalline copper oxide (CuO), cuprous oxide (Cu2O) and copper (Cu) phases of the copper oxide composites constitute of irregularly spheroidal particlesµ with nanoparticles aggregate on the surface. Gas pressure during plasma arc process noticeably influences the composition and solar radiative properties of the composite materials. Among the samples studied, the composites synthesized with an arc current of 80 A and a pressure of 300 Torr exhibited the highest near infrared diffuse reflectance, providing a total solar reflectance of 22.96%. The mixed phase composition together with the nanostructures among the composites are considered to contribute to the excellent near infrared reflectance of copper oxide composites. Low reflectance in the visible region combined with high reflectance in the near infrared region make this composite material a good candidate for solar reflective coating which will demonstrate black appearance but keep a cool surface under solar irradiation.

Solar driven water oxidation by a bioinspired manganese molecular catalyst.

A photoelectrochemical cell was designed that catalyzes the photooxidation of water using visible light as the sole energy source and a molecular catalyst, [Mn(4)O(4)L(6)](+) (1(+), L = bis(methoxyphenyl)phosphinate), synthesized from earth-abundant elements. The essential features include a photochemical charge separation system, [Ru(II)(bipy)(2)(bipy(COO)(2))], adhered to titania-coated FTO conductive glass, and 1(+) embedded within a proton-conducting membrane (Nafion). The complete photoanode represents a functional analogue of the water-oxidizing center of natural photosynthesis.

Fluorescence of ceramic color standards.

Fluorescence has been found in color standards available for use in calibration and verification of color measuring instruments. The fluorescence is excited at wavelengths below about 600?nm and emitted above 700?nm, within the response range of silicon photodiodes, but at the edge of the response of most photomultipliers and outside the range commonly scanned in commercial colorimeters. The degree of fluorescence on two of a set of 12 glossy ceramic tiles is enough to introduce significant error when those tiles have been calibrated in one mode of measurement and are used in another. We report the nature of the fluorescence and the implications for color measurement.