Enhanced visible light photocatalytic activity of P-block elements (C, N and F) doped porous TiO2 coatings on Cp-Ti by micro-arc oxidation

P-block elements (C, N and F) doped porous TiO2 coatings were developed on commercially pure titanium by micro-arc oxidation (MAO) for visible light photocatalytic activity. Porous structured photocatalytic system has been developed with the use of different electrolytes. The geometry of porous coatings was analyzed by optical profilometer and their results confirmed that the surface roughness, width and depth of pores vary with respect to the doped elements. The anatase and rutile phase percentage in the pure and doped TiO2 coatings was estimated by their XRD patterns. EDS analysis confirms the presence of C, N and F (2.2, 3.1 and 3.8 at.%) doped elements in the TiO2 coatings. The band gap energies of C, N and F doped TiO2 coatings were significantly reduced into 3.03, 3.04 and 3.02 eV, respectively than pure TiO2 (3.15 eV) coating. The photoluminescence study indicates the formation of additional electronic states by the influence of C, N and F doped elements in TiO2. This resulted in the reduced rate of recombination of photogenerated electron–hole pairs. The photocatalytic activity of MAO produced pure and doped TiO2 coatings have been investigated with methylene blue dye as a target pollutant. The results confirmed that the doped TiO2 showed higher rate of dye degradation than pure TiO2. In particular F doped TiO2 revealed higher photocatalytic activity among all other doped TiO2.