H-2 EVOLUTION FROM VARIOUS AQUEOUS-SOLUTIONS OVER THERMALLY REDUCED TIO2 AND PT-TIO2 POWDER

The reduction of H//2O (or H** plus ) to form H//2 by reduced TiO//2 and Pt-TiO//2 was studied in distilled water and aqueous solutions of HCl, H//2SO//4, HNO//3, and NaOH. Over the reduced TiO//2 powder, H//2 evolved moderately in distilled water and Ti**3** plus ions on the surface were presumed to be active sites for the reaction. The reaction in aqueous NaOH solution proceeded similarly to that in water while it was strongly suppressed in aqueous HCl and H//2SO//4 solutions. It was found that the suppression of H//2 evolution is due to protons in the solution. Over reduced Pt-TiO//2, H//2 evolved rapidly from all solutions, except HNO//3. In aqueous HNO//3 solution, NO//3** minus was reduced to NH//3 over reduced TiO//2 and Pt-TiO//2.