Designing Nanoparticles to Harness Solar Energy for Environmental Remediation
Energy, water and environment are the three biggest problems facing mankind in the coming 50 years. In particular, the demand for clean drinking water, an extremely sensitive commodity, becomes more challenging in view of the ever-growing population. The needs to develop ecologically clean solar-induced chemical processes, such as photocatalysis, are at presence limited by low quantum efficiencies. Hence the presentation illustrates the chronological development of highly efficient photocatalytic nanoparticles for water purification via an elegant one-step Flame Spray Pyrolysis (FSP).
The first part of the presentation entails the development of UV-activated TiO2 nanoparticles. Using the Degussa P25 TiO2 as a benchmark photocatalyst, the FSP TiO2 was shown to be more efficient for the mineralisation of pollutants requiring direct charge transfer such as the saccharides.
The second part illustrates the co-precipitation of highly dispersed noble metals (demonstrated here with Pt) on TiO2 in the flame. Deposition of Pt resulted in a large Schottky barrier at the Pt-TiO2 junction and hence allowing for efficient electrons trapping. In other words, the photocatalytic performance was enhanced compared to bare TiO2. Interestingly, simple pretreatment of the Pt/TiO2 with formic acid further improved the photocatalytic mineralisation of some model pollutants.
The last part of the presentation involves the development of visible-light-activated Fe-doped TiO2 nanoparticles. Substitutional doping of Fe in TiO2 induces sub-bandgap energy levels and hence allows for visible light absorption. Under visible light irradiation, FSP-made Fe-TiO2 improved the photocatalytic mineralisation of oxalic acid by more than 6 times, with respect to P25 and FSP TiO2.