Synthesis and Photocatalytic Degradation of Cu_1.94S-SnS Nano-heterojunction

In this study, Cu1.94S-SnS nano-heterostructures were synthesized using the methods of thermal injection-cation exchange to enhance the activity of photocatalytic degradation of hazardous dyes. First, we stirred and mixed octadecene, oleylamine and copper chloride under argon atmosphere and raised the temperature to 180 degrees C for 15 min. The precursor of Cu1.94S was cooled to 140 degrees C, and then tert-dodecanethiol (t-DDT) was added. This solution was rapidly raised to 180 degrees C for 30 min, and then cooled in ice water to obtain the product of Cu1.94S. Similarly, tin chloride and oleylamine were mixed under argon atmosphere and raised to 160. for 30 min, then cooled to 80, 120 and 160 degrees C, respectively. The Cu1.94S and tri-n-octylphosphine suspensions were injected into the precursor solution to react for 30 min. The samples were characterized using various analytical techniques, including high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, STEM energy-dispersive spectroscopy (STEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). At lower temperatures (80 and 120 degrees C), sheet-like Cu1.94S-SnS single-particle nano-heterojunctions were obtained with size of about 57 nm. In contrast, regular shaped heterojunctions could not be obtained at a high temperature (160 degrees C). The Uv-visible near infrared spectrophotometer (UV-Vis-NIR) absorption spectra revealed that the synthesized Cu1.94S-SnS nano-heterostructures exhibited higher light absorption in the visible range. Photocatalytic degradation of methylene blue and tetracycline was used to evaluate the photocatalytic performance of the products. The results showed that the heterostructure effectively improved the photocatalytic activity of the parent material. Specifically, the photodegradation rate of methylene blue (MB) increased from 56% (parent material Cu1.94S) to 98% (Cu1.94S-SnS nano-heterojunction), indicating a significant enhancement in photocatalytic activity. And the photodegradation rate of tetracycline (TC) was also increased by about 5 times. Overall, the synthesized Cu1.94S-SnS heterostructures possessed superior photocatalytic activity, which could be attributed to the effective charge sep-