Construction of MgIn2S4/ZnIn2S4 micro-flowers: Efficient degradation of tetracycline hydrochloride over a wide pH range

The high recombination rate of photogenerated carriers limited the wide application of ternary metal sulfides with appropriate energy band structure and excellent light absorption properties. In this article, the microflower-like MgIn2S4/ZnIn2S4 heterojunction was constructed to overcome the above faults. Various characterizations revealed that the loading of MgIn2S4 provided more reactive sites for the photocatalytic reaction, and induced the generation of more photogenerated charge. Meanwhile, the heterostructure forming between MgIn2S4 and ZnIn2S4 significantly reduced the recombination rate of photogenerated carriers. For the 30% MgIn2S4/ZnIn2S4 (MZ-30) composite, the removal efficiency of tetracycline hydrochloride (TCH) reached 96.21% under the optimal experimental conditions. Surprisingly, it still maintained high removal efficiencies both acidic and alkaline conditions. MgIn2S4/ZnIn2S4 composite had the advantages like short removal time, wide pH application range, and could efficiently degrade a variety of antibiotics at the same time. Mass spectrometry analysis suggested that TCH molecules eventually turned into carbon dioxide and water by the ring-opening and functional group cracking reactions. Finally, the possible mechanism of photocatalytic degradation of TCH was proposed by combining the band position analysis and active species trapping test.