In-situ generated SrWO4/g-C3N4 heterojunction photocatalyst for enhanced visible light degradation activity of tetracycline

Abstract

A novel SrWO4/g-C3N4 heterojunction was formed by simple one-pot calcination process and the wide-band gap semiconductor SrWO4 was in-situ formed on g-C3N4. The prepared photocatalysts were characterized by X-ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscope, Fourier transform infrared spectroscopy, UV–vis diffuse reflectance spectra and Photoluminescence Spectroscopy to investigate the structures, morphology and optical properties of the synthesized materials. The results revealed that SrWO4 nanoparticles were uniformly distributed on the surface or inside of g-C3N4 to form a compact heterostructure and improved the photocatalytic performance of the material. The binary heterojunction showed better photodegradation efficiency of tetracycline (TC) than pure g-C3N4 and SrWO4. 88.57% of TC could be degraded by 8% SrWO4/g-C3N4 in 2 h under the best experimental conditions. The pH value had little influence on the degradation effect, and the TC degradation rate under strong acid reached 93.94%. In addition, 77.42% TC was still degraded after the fourth cycle. It was concluded that the enhancement of photocatalytic activity due to the inhibition of electrical charge recombination and the improved light absorption capacity. Finally, free radicals capture experiment proved that·O2- was the most important active factor of TC degradation, and the possible photocatalytic mechanism was proposed.