Hydrogen production from water splitting under UV light irradiation over Ag-loaded mesoporous-assembled TiO2–ZrO2 mixed oxide nanocrystal photocatalysts

Hydrogen production from the photocatalytic water splitting reaction is very attractive because it is an environmentally friendly process, where hydrogen is produced from two abundantly renewable sources, i.e. water and solar energy, with the aid of photocatalysts. TiO2 is the most widely investigated photocatalyst; however, it alone still exhibits low performance to photocatalytically produce hydrogen. Hence, the aim of this work focused on the enhanced photocatalytic hydrogen production over Ag-loaded mesoporous-assembled TiO2–ZrO2 mixed oxide nanocrystal photocatalysts under UV light irradiation. The TiO2–ZrO2 mixed oxides with various TiO2-to-ZrO2 molar ratios were synthesized by a sol–gel process with the aid of a structure-directing surfactant, followed by Ag loading via a photochemical deposition method. The influences of photocatalyst preparation parameters, i.e. calcination temperature, phase composition, and Ag loading, were studied. The results revealed that the mesoporous-assembled TiO2–ZrO2 mixed oxide nanocrystal photocatalyst with a TiO2-to-ZrO2 molar ratio of 93:7 calcined at 500 °C exhibited the highest photocatalytic hydrogen production activity, and the Ag loading of 0.5 wt.% further greatly enhanced the photocatalytic activity of such TiO2–ZrO2 mixed oxide photocatalyst.

► The Ag-loaded mesoporous-assembled TiO2–ZrO2 mixed oxide nanocrystal photocatalysts were applied for photocatalytic hydrogen production from water splitting. ► The optimum TiO2-to-ZrO2 molar ratio of the synthesized TiO2–ZrO2 mixed oxide nanocrystal photocatalyst was found to be 93:7, exhibiting the highest photocatalytic hydrogen production activity. ► The higher thermal stability of the host mesoporous-assembled TiO2 nanocrystal photocatalyst was achieved by the ZrO2 incorporation. ► The optimum Ag loading of 0.5 wt.% by the photochemical deposition method on the 0.93TiO2–0.07ZrO2 mixed oxide nanocrystal photocatalyst considerably enhanced its photocatalytic hydrogen production activity.