Synthesis of ammonium and sulfate ion-functionalized titanium dioxide for photocatalytic applications

Abstract

Due to high band gap energy the optimum photocatalytic activities can only be achieved under UV light, thus limiting the practical application of TiO2. In this study, a method combining NH4+/SO42−-functionalization technique and post-treatment was developed and successfully applied to synthesize photoactive TiO2 samples which showed higher photocatalytic activity than the commercial P25 TiO2 under visible light radiation. The results also showed that the addition of (NH4)2SO4 surface functionalization on TiO2 increased the photocatalytic activity, which could be due to the combined effect of crystallinity and band gap energies. Moreover, the results showed that calcination temperature was inversely proportional to photocatalytic activity. The degradation efficiency for methylene blue under visible light was improved by ~2 times from 10.7% for P25 nano Degussa TiO2 to 20.2% for the synthesized sample. The band gap energies were also reduced from 3.7 to 3.4 eV (under UV–Vis direct transition mode) indicating a red shift towards higher wavelength.