Facile synthesis of a symmetrical squarylium dye sensitized SnIn4S8 composites with enhanced photocatalytic activity under visible-light irradiation

Abstract

A symmetrical squarylium dye, 1,3-bis[2,3,3-trimethylnaphto(1,2-d)pyrrole]squaraine (SQ) sensitized SnIn4S8 composites with different mass ratio of SQ were facilely prepared by the ultrasonic method. The resulting composites were characterized by the scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra, UV–Vis diffuse reflectance spectroscope, photoluminescence spectra, photoelectric current and thermogravimetric-differential thermogravimetric analysis. The highest occupied molecular orbital and lowest occupied molecular orbital states of SQ were calculated by Gaussian 98 at the B3YP/6-311+G(d,p) level. The visible light photocatalytic activities of SQ/SnIn4S8 composites were evaluated using the degradation of malachite green as a photodegradation target. The results showed that the SQ/SnIn4S8 composites exhibited significantly enhanced photocatalytic activities under visible-light irradiation. The maximum photocatalytic activity of the SQ sensitized SnIn4S8 was found at a 10%-SQ/SnIn4S8 composites (mass ratio of SQ to SnIn4S8 was 1:10), and its degradation efficiency of MB reached approximately 90.5% after 25 min visible-light irradiation. Furthermore, the kapp value of 10%-SQ/SnIn4S8 composites (0.0587 min−1) was 2.37 times larger than that of bare SnIn4S8 (0.0248 min−1).