Investigation on the degradation mechanism of tetracycline hydrochloride by self-assembled Ni-doped MoS2 photocatalyst†

Constructing defects in semiconductors is one of the important strategies to enhance their catalytic performance. The results indicate that Ni doping introduces impurity energy level defects in MoS₂, which significantly improves the photocatalytic performance of the material. Specifically, the optimal Ni_0.08Mo_0.92S₂ sample achieved a decolorization rate of 81.42% for high-concentration TCH within 135 minutes, with a reaction rate 2.06 times that of pure MoS₂. After three cycles, Ni_0.08Mo_0.92S₂ still exhibited excellent stability. XPS confirmed the successful doping of Ni and revealed the chemical states of the elements. BET analysis demonstrated that Ni doping increased the specific surface area of the photocatalytic material, exposing more active sites. Electrochemical and PL spectroscopy analyses confirmed that Ni doping facilitated the separation of electron–hole pairs and retained electrons and holes with high redox capabilities. Trapping experiments identified h⁺ and O₂⁻˙ as the primary active species involved in the reaction, which was further supported by ESR results. This study provides a novel strategy for constructing impurity energy levels through elemental doping to enhance the removal of antibiotics.