TiO2 promoted by two different non-noble metal cocatalysts for enhanced photocatalytic H2 evolution

TiO2 photocatalysts modified by cobalt and nickel cocatalysts were prepared via polymerized complex method (PCM) and evaluated by photocatalytic hydrogen evolution. Hydrogen generation in 6 h for the TiO2 promoted by cobalt and nickel (0.1%Co + 0.2%Ni/TiO2) is about two times (2456 μmol H2) compared to that of TiO2 promoted only by cobalt (1180 μmol H2 for 0.1%Co/TiO2) or nickel (1127 μmol H2 for 0.2%Ni/TiO2), and mechanically mixed TiO2 promoted by cobalt and TiO2 promoted by nickel (0.1%Co/TiO2:0.2%Ni/TiO2 = 1:1 (m/m), 1282 μmol H2). The high photocatalytic H2 evolution activity over TiO2 promoted by cobalt and nickel is ascribed to enhanced photo response due to the presence of cobalt and nickel impurity level, and effective separation of photogenerated electrons and holes due to the synergistic effect of cobalt and nickel, which serve as active sites for H2 evolution reaction (HER) and oxidation reaction (OR) respectively. This study demonstrates a viable strategy to design more active photocatalysts for photocatalytic H2 evolution by substituting noble metals with more abundant elements using as HER and OR cocatalysts, respectively.