Preparation of C/Ho co-doped TiO2 for enhancing the photocatalytic degradation efficiency of tetracycline hydrochloride.

A C/Ho co-doped TiO2 catalyst was prepared by the precipitation–calcination method using Ti3C2Tx as the precursor and carbon source. X-ray diffractometry, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption–desorption isotherms, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and photoelectrochemical measurements were used for characterization. The C doped anatase TiO2 prepared by calcining Ti3C2Tx maintained the two-dimensional lamellar structure of the Ti3C2Tx precursor, and the carbon dopant was present on the surface of TiO2 in the form of C–O and C＝O, whereas Ho3+ was mainly doped into the lattice of TiO2, forming Ho–O bonds with oxygen instead of Ti4+. The band gap of the C/Ho co-doped TiO2 photocatalyst was reduced as compared to that of pristine TiO2, which can improve the utilization efficiency of visible light. When the doping ratio of Ho was 5% (CHT-0.05), the photocatalyst had the highest photocurrent and degradation efficiency of tetracycline hydrochloride (86.4%). The reaction mechanism for the photocatalytic degradation of TCH by the C/Ho co-doped TiO2 photocatalyst was investigated and showed that superoxide radicals (˙O2−) and holes (h+) were the main species that influenced the results. The prepared photocatalyst had good catalytic performance over four cycles, and it was stable and suitable for wastewater treatment. [ABSTRACT FROM AUTHOR]