“…The last two crystal structures are thermodynamically more stable [ 9 ] with the band gap energy (Eg) of ±3.0–3.2 eV. When compared to the rutile structure, the anatase TiO 2 phase structure has more excellent photo-catalytic properties including electron transfer rate that is 89 times greater, chemically and biologically inert, mechanical toughness, low cost and non-toxic [ 10 , 11 , 12 , 13 , 14 ]. The photocatalytic process requires photon energy.…”