High photoactivity of Zr_xO_y-Bi₂O₂(CO₃) composite materials prepared by one-step synthesis for efficient photodegradation of 4-chlorophenol in water

The ZrBi composite materials were prepared in a single step by the chemical co-precipitation method. Bi₂O₂(CO₃) joined Zr_xO_y modifying the mole percentage from 5 to 11 mol %. ZrBi composites dried at 80 °C were characterized by: XRD, FTIR, DRS, SEM, N₂ adsorption, HR-TEM, PL, XPS and EDS-SEM. Later they were evaluated in the photodegradation of 4-Chlorophenol under UV irradiation. The degradation and mineralization percentages were determined after 150 min of reaction by UV–vis spectroscopy and Total Organic Carbon (TOC), respectively. The composite containing 9 mol % of Bi₂O₂(CO₃) (ZrBi-9) with a specific volume of 0.03 m³/kg in solution with specific catalyst density of 1*10⁻³ kg/L, showed the highest photoactivity with 96 % photodegradation, a higher value compared to that obtained with the reference material TiO₂-P25 (72 %). Finally, a possible reaction mechanism was proposed based on recent studies, which allow to follow the formation of active species [rad]OH, [rad]O2⁻ and h⁺. The formation of [rad]OH radicals was measured by fluorescence spectroscopy while the inhibition of [rad]O₂⁻ radicals as well as the scavenge of h⁺ were determined by UV–vis spectroscopy. The results showed that ZrBi composite materials do not promote [rad]OH radical formation. The scavenge of h⁺ showed a total loss of photoactivity and the inhibition of [rad]O₂⁻ in the reaction medium results in a partial decrease of photoactivity. The formation of heterojunctions, the presence of localized states and oxygen vacancies in the synthesized materials promise an excellent alternative for the rapid photodegradation of 4-Chlorophenol under UV radiation.