Influence of Cd, Mn, and Co addition on the structural and optical properties of TiO2 crystal

Abstract

Abstract Synthesis of TiO2-M (M = Cd, Mn, Co) has been done by the sol gel method. Solution of titanium (IV) isopropoxide was hydrolyzed using a solution of glacial acetic acid at a temperature range of 10-15 °C to obtain a sol, subsequently heated to form a white gel. Ion solution Cd (II), Mn (II) and Co (II) each added to the gel TiO2 with Ti:M mole ratio (M= Cd, Mn, Co) = 3:1 (mol/mol). After calcination process at a temperature of 400 °C, we have obtained TiO2 and TiO2-M (Cd, Mn, Co). Characterization of the samples with XRD showed TiO2-M (M = Cd, Mn, Co) produces crystalline of anatase TiO2 phase. SEM-EDX results showed differences in the amount of metal contained within TiO2-M (M= Cd, Mn, Co) that is equal to 8.62% (w/w) Cd; 3.26% (w/w) Mn; 0.721% (w/w) Co. The addition of transition metals ion as impurities as Cd (II), Mn (II), or Co (II) have inhibited the growth of TiO2 crystals. The insertion of metal ions in the TiO2 were also affected the optical properties shown by the energy band gap (Eg) shift in order of Eg TiO2 (3.35 eV)>TiO2-Cd (3.10 eV)>TiO2-Co (3.00 eV)>TiO2-Mn (2.5 eV). The eletronic structures of TiO2 doped 3d transition metals showed that an electron occupied level energy occurs. Electron from dopand are somewhat delocalized, thus significantly contributing to the formaton of the valece band with O p and Ti 3d electrons. Based on a comparation with the absorption data, we show that t2g state of the dopand plays a significant role in the photoresponse of TiO2 under visible irradiaton.