Photodegradation on Carbon-Containing Surfaces

Ti02 with a rather low carbon content [154-158], This may be indicative of an increment of Ti02 snrface electric charge in the composites, related directly to the presence of the carbon phase. 

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to study the morphology and microstructure of carbon-Ti02 composites. In the case of CNT-Ti02 composites, observations on CNT embedded in Ti02 matrix [111,115] and fine coating of Ti02 on a CNT surface [107,112-114,116,117] are reported. 

X-ray photoelectron spectroscopy (XPS) is used to probe the chemical environment of the elements in the near-surface range of carbon-Ti02 composites. Titanium cations in the composites can be found in oxidation state IV, as in stoichiometric Ti02 [100,123,129,150,172,188,193]. The XPS data support the formation of surface oxygen groups, with different carbon valences, on the surface of the carbon phase [100,116-118,123,129,150,159,181,188,193]. 

In addition, there are some other characterization techniques that can be used to examine the carbon-Ti02 composites, including Raman spectroscopy [40,123], atomic force microscopy (AFM) [106,123], thermogravimetric and differential thermal analysis (TGA-DTA) [26,125], determination of pHpzc [19,29], and electron paramagnetic resonance (EPR) [126,127], 

In heterogeneous photocatalysis experiments, especially in reactions dealing with water detoxification and gaseous pollutant removal, the disappearance of target chemicals, the degree of mineralization of total organic carbon (TOC), and the reaction intermediates can be detected by spectroscopic optical methods (UV-vis and IR), TOC measurements, and chromatographic analysis. 

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