Application of EPR techniques in the study of photocatalytic systems

A brief introduction to the principles of EPR spectroscopy (resonance condition, g-factor, hyperfine interaction, line shape, and signal intensity) is followed by the illustration of its potential to monitor the paramagnetic centers and radicals generated upon the photoactivation of titania-based nanocrystalline photocatalysts and their dispersed systems, supported by a large number of EPR investigations of various pristine and doped/modified titania nanostructures accomplished during the past years. The power and limitations of the EPR spin trapping and spin scavenging techniques in the detection and identification of nonpersistent radical intermediates generated in the photocatalytic particulate systems in water or organic solvents are also discussed in detail.