Preparation of TiOx-C Nano-Composite Films as Solar Selective Absorbers by Sol-Gel Method

TiOx-C nano-composite films were prepared by a sol-gel process, followed by carbonization in vacuum: A soluble organic compound, salicylic acid, coupled with a quasi-crystallized benzene ring structure was served as carbon sources; acetylacetone was used as complexing agent. Using scanning electron microscope, high-resolution transmission electron microscope, four-point probe, spectroscopic ellipsometer and spectrophotometer, the structure, composition and the performance of the films were investigated. The results reveal that the nano-composite film is made up by nano-graphites embedded in amorphous matrix, presenting outstanding optical selectivity (alpha=0.957 and epsilon=0.179). Owing to the excellent chemical and thermal stability of both carbon and TiOx, the composite film also presents prominent durability after subject to a 500 degrees C, 30 h aging test. In terms of these results, the composite film is found to be a potential candidate for selective solar absorbers.