However, a change in emission intensity peaks is observed: a decrease in the PL intensity for Ch/TiO2, Th/TiO2 and Tp/TiO2 samples (where manganese oxides are nanosized) and a little increase in the PL intensity for b-MnO2/TiO2 sample (where manganese oxide is microsized).Since the manganese oxides are deposited at the surface, their presence should not affect the band gap of TiO2 but can change the surface state (surface defect and hydroxyl group’s nature and density). The increase of the luminescent emission intensity when MnO2 was added is probably due to the presence of some different hydroxyl groups(Mn-OH).