One-step hydrothermal synthesis of visible-light-driven In2.77S4/SrCO3 heterojunction with efficient photocatalytic activity for degradation of methyl orange and tetracycline

The In2.77S4/SrCO3 heterojunction photocatalyst had been prepared by one-step hydrothermal method. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrometry, UV–Vis diffuse reflectance spectroscopy and electrochemical impedance spectroscopy were used to analyze the structure, morphology, chemical compositions, optical properties and charge carrier behaviors of the as-prepared In2.77S4/SrCO3 hybrids, respectively. Experimental results revealed the SrCO3 could obviously improve the recyclability and photocatalytic activities of In2.77S4 nanosheets for both methyl orange and tetracycline oxidation under visible light. The photocatalytic degradation efficiency of the as-obtained In2.77S4/SrCO3 hybrids was first increased and then decreased with increasing the molar ratio of Sr(NO3)2 to In(NO3)3·4.5H2O. When it was 0.4:1, that of the as-prepared hybrids with the band gap of 1.63 eV reached the maximum of 96.0% in 30 min for methyl orange and 82.7% in 20 min for tetracycline. These were higher than 88.0% and 40.0% of In2.77S4 nanosheets as well as 0.8 and 1.8% of SrCO3 particles, respectively. After three cycles, its photocatalytic efficiency still possessed 92.7% for methyl orange and 80.3% for tetracycline, which were much higher than 35.3% and 11.3% of In2.77S4 nanosheets. Moreover, the possible photocatalytic degradation mechanism of the In2.77S4/SrCO3 hybrids was also proposed.