Hydrogen generation from water/methanol under visible light using aerogel prepared strontium titanate(SrTiO3) nanomaterials doped with ruthenium and rhodium metals

Abstract

Nanostructured strontium titanate visible-light-driven photocatalysts containingrhodium and ruthenium were synthesized by a modified aerogel synthesis usingruthenium chloride and rhodium nitrate as dopant precursors, and titaniumisopropoxide and strontium metal as the metal sources. The well-defined crystallineSrTiO3 structure was confirmed by means of x-ray diffraction. After calcination at500 °C, diffuse reflectance spectroscopy shows an increase in light absorption at 370 nm due to the presenceof Rh3 + ; however an increase of the calcination temperature to600 °C led to a decrease in intensity, probably due to a loss of surface area. An increase in the rhodiumdoping level also led to an increase in absorption at 370 nm; however, the higher amounts of dopantlowered the photocatalytic activity. The modified aerogel synthesis allows greatly enhancedH2 production performance from an aqueous methanol solution under visible lightirradiation compared with lower surface area conventional materials. We believethat this enhanced activity is due to the higher surface areas while high qualitynanocrystalline materials are still obtained. Furthermore, the surface properties ofthese nanocrystalline aerogel materials are different, as exhibited by the higheractivities in alkaline solutions, while conventional materials (obtained via hightemperature solid-state synthesis methods) only exhibit reasonable hydrogenproduction in acidic solutions. Moreover, an aerogel synthesis approach gives thepossibility of thin-film formation and ease of incorporation into practical solar devices.