The BET surface area of nitrogen-doped TiO2 samples (0.5 and 2.0M of guanidine carbonate source)
was investigated. When used 0.5M of guanidine carbonate as N source, it was found that surface area was
5.817m2/g. When the concentration of guanidine carbonate was increased to 2.0M, the surface area was
decreased to 2.937m2/g. On the other hand, the product from urea source of 0.5M was showed surface
area around 7.452m2/g. For HM-TiO2 and P25-Degussa, the surface area was 97.877 and 50m2/g,
respectively.