Characterization of molybdenum black coatings on zinc substrates

Molybdenum black solar selective coatings have been prepared by a simple chemical conversion method on chemically etched zinc substrates. These coatings have been characterized using X-ray diffraction, electron diffraction, XPS and VIS-IR reflectance spectroscopy. Maximum solar absorptance obtained from these coatings was about 0.87 with an emittance of 0.13-0.17. Selectivity of the coatings, mainly attributed to the coating surface morphology, was studied by SEM. Structural studies show that the coating consists of a non-stoichiometric oxide of Mo, namely Mo4O11. XPS depth profiling studies show that the oxidation state of Mo reduces from +5 to +4 after argon ion bombardment.