Efficient Solar Energy Conversion Using CaCu3Ti4O12 Photoanode for Photocatalysis and Photoelectrocatalysis

Abstract

A highly efficient third generation catalyst, CaCu3Ti4O12 (CCTO) shows excellent photoelectrochemical (PEC) and photocatalytic ability. As only 4% part of the solar spectrum covers UV light, thus it is highly desirable to develop visible light active photocatalyst materials like CCTO for effective solar energy conversion. A direct band transition with a narrow band gap (1.5 eV) was observed. Under light irradiation, high photocurrent density was found to be 0.96 mA/cm2, indicating the visible light induced photocatalytic ability of CCTO. Visible light mediated photocatalytic and photoelectrocatalytic degradation efficiency of CaCu3Ti4O12 pellets (CCTO) was investigated for three classes of pharmaceutical waste: erythrosin (dye), ciprofloxacin (antibiotic) and estriol (steroid). It is found that the degradation process follows first order kinetic reaction in electrocatalysis, photocatalysis and photoelectrocatalysis and high kinetic rate constant was observed in photoelectrocatalysis. This was quite high in comparison to previously reported methods.

From Synthesis to Applications: Copper Calcium Titanate (CCTO) and its Magnetic and Photocatalytic Properties

“…Accelerated industrial development and population growth forced science to find “green solutions” to solve problem of pollutions, by using a renewable energy such as visible light. The decomposition reaction of pollutants and pharmaceutical waste occurs only upon UV lights, in which UV light shared 4 % of wavelengths with visible light . TiO 2 is acclaimed as a UV‐light photocatalytic.…”

“…Perovskite structure ABO 3 has been investigated because A site is shared by two cations without causing a disordered lattice . CaCu 3 Ti 4 O 12 perovskite showed a good photo‐catalytic reaction against water pollutants and pharmaceutical waste . As mentioned above, the specific structure of CCTO is the key of this function.…”

“…As mentioned above, the specific structure of CCTO is the key of this function. It is related to photo‐induced charge transition from ground state Cu 2+ ,Ti 4+ to excited state Cu 3+ ,Ti 3+ that CCTO have a visible light activity and they observed a direct band transition with a small band gap (1.52 eV) . CCTO was prepared using oxalate route to decompose pharmaceutical waste (erythrosin (dye), ciprofloxacin (antibiotic) and estriol (steroid)), sol‐gel and solid route to break‐down water pollutants such as 4‐chlorophenol …”

“…Kushwaha et al . demonstrate that after 40 min of exposure a total decomposition of erythrosine dye (solution turned from pink to colorless).…”

“…The crystalline phases of barium titanate varied at different temperatures. It is paraelectric at high temperature with a cubic phase, tetragonal and polarized below its Curie temperature (T c =120 °C), orthorhombic and polarized below 5 °C, and rhombohedral and polarized below −90 °C.…”