(a) The figure shows the color change of the photocatalyst developed by the research team. It shows that the reduced titanium dioxide absorbs light more towards the right and the color gets darker.
(b) A graph comparing the methane production efficiencies of the photocatalysts developed by the research team and the existing photocatalysts. The methane production efficiency of the photocatalyst (0.35-BT-30) developed by the team is superior to other photocatalysts.
(c) The energy level diagram of the photocatalyst developed by the research team. It shows the characteristic that the oxygen atoms on the surface of titanium dioxide are defected and the band gap is controlled by changing oxidation number from 4 to 3.