ACTIVITY OF CHROMIUM-ION-DOPED TITANIA FOR THE DINITROGEN PHOTOREDUCTION TO AMMONIA AND FOR THE PHENOL PHOTODEGRADATION

The photoreduction of dinitrogen to ammonia in a gas-solid regime and the photodegradation of phenol in an aqueous liquid-solid regime were investigated by using a series of chromium-ion-containing titania specimens. For the same photoreactions, two iron-ions-containing titania specimens were also studied for comparison. For the photoreduction reaction it was found that the presence of the dopants is essential for the occurrence of the photoreactivity, the iron-ions-containing specimens being more effective than those containing chromium ions. For the photooxidation reaction the presence of the dopants instead is not essential; the photoreactivity of titania is not affected or, in some cases, detrimentally affected. The two contrasting behaviors are explained by taking into account the differences in the gas-solid and liquid-solid interfaces.