In situ tuning of band gap of Sn doped composite for sustained photocatalytic hydrogen generation under visible light irradiation

The significance of Sn dopant on the photocatalytic performance of Iron/Titanium nanocomposite towards photocatalytic hydrogen generation by water splitting reaction is investigated. Iron/Titanium nanocomposite modified by Sn4+ dopant acts as a suitable photocatalyst for induced visible light absorption facilitating pronounced charge separation efficiency. Various characterization techniques reveal the heterojunction formation of hematite Fe2O3 with anatase - rutile mixed phase of TiO2 employing Sn doping, where Sn4+ dopant accomplishes the phase transformation of anatase to rutile, entering into the TiO2 lattice. This extended the lifetime of photogenerated charge carriers and enhanced the quantum efficiency of the photocatalyst. The band gap of the nanocomposite is tuned to ~2.4 eV, favoring visible light absorption. A hydrogen generation activity of 1102.8 μmol, approximately five times higher than the lone system (216.5 μmol) is achieved for the 5% Sn doped system for an average of 5 h. Heterojunctions of hematite with anatase-rutile mixed phase, generated as a consequence of tin doping facilitated the enhanced hydrogen generation activity of photocatalyst.