Influence of Al-doped SrTiO3 cores on hydrogen evolution from SrTiO3/TiO2 core-shell catalysts

The hydrogen produced by Al-doped SrTiO3/TiO2 core-shell catalysts with a range of Al-doped SrTiO3 cores and the same TiO2 shell are compared. The study included SrTiO3 cores doped with different amounts of Al (0, 1, 2, or 3 mol%) added at different points in the synthesis (prior to or during the molten salt treatment) and at different temperatures (900 degrees C, 1000 degrees C, and 1100 degrees C). It was found that core-shell catalysts with different cores had hydrogen generation rates that varied by a factor of more than 40 and varied with the processing parameters in the same way as the hydrogen generation rates of the cores alone. The best catalysts had 2 or 3 mol% added Al, added during treatment in a SrCl2 molten salt at 1000 degrees C or 1100 degrees C. Because the core absorbs most of the light, its ability to separate and transport photogenerated charge carriers dominates the properties of the core-shell catalyst. This indicates that, to optimize the properties of core-shell catalysts, it is essential to optimize the properties of the core. While the shell can be important to protect the core from degradation, it is not as important to the overall reactivity as the core.