Antimonene Quantum Dots: Large-scale Synthesis via Liquid-phase Exfoliation

Since the rediscovery of black phosphorus as a fascinating two-dimensional material,other two-dimensional materials comprising group V-A elements have attracted tremendous interest, such as antimonene. Since 2015, besides intensive research efforts on the atomic structures, electronic properties and synthesis methods of antimonene, scientists have conducted applied researches on semiconductor and nonlinear optical devices, molecular adsorption and thermoelectric applications based on antimonene. In addition, antimonene quantum dots (SbQDs) as derivatives of antimonene, have also been studied recently, and their potential applications in photothermal therapy have been reported. To further explore the unique properties and potential applicationsof SbQDs, it is important tosynthesize large amounts of high-quality SbQDs. In this work, antimonene samples were prepared by sonication-assisted liquid exfoliation method. Antimony powders (200 mg) were dispersed in 200 mL water, C2H5OH and 1-methyl-2-pyrrolidone (NMP) solvents separately and sonicated for 10 h at a power of 180 W. Thereafter, the suspensions were centrifuged at 6000 r.min(-1) for 20 min, and the supernatant containing antimonene samples were decanted and characterized. The dispersion concentration of antimonene samples in the three solvents (water, C2H5OH and NMP) were measured as 0.57, 1.04, and 4.27 ug.mL(-1), respectively. However, the antimonene concentrations in water, C2H5OH and NMP dropped by 73.7%, 30.8% and 10.5%, respectively, after standing for 96 h. Thus, antimonene dispersed in NMP demonstrated the highest concentration and best stability, which indicates that NMP is more suitable for antimonene exfoliation. Furthermore, transmission electron microscopy (TEM) studies revealed that only the samples prepared in NMP were morphologically quantum dots, while antimonene samples obtained in the other two solvents were mainly nanosheets. The obtained SbQDs in NMP had a lateral size of approximately 3.0 nm. High-resolution transmission electron microscope (HRTEM) also confirmed the good crystal quality of theobtained SbQDs. In addition, we measured the turbidities of antimonene dispersed in those three solvents at various concentrations. As theoretically predicted, the turbidity of antimonne dispersions linearly depends on the concentraion; thus, the antimonene concentrations can be calculated by measuring the turbidity through an optical method. Thus, this study provides a high-throughput, nondestructive method for determining antimonene dispersion concentration, which will faciliate further research in this area.