Fig. 6

Positive correlation between sulfur defects and photodynamic efficiency in QDs. a Absorption spectra of three kinds of MoS₂ QDs in the presence of ABDA under light irradiation (0.1 W cm-2, 8 min). b Typical decomposition rate of the photosensitizing process, where A₀ is the absorbance of initial absorbance of ABDA and A is the absorbance of ABDA under light irradiation at different time points (Full data plots can be found as Supplementary Figure 19). c Relative ¹O₂ quantum yield of two MoS₂ QDs groups relative to MoS₂-D_L QDs. Mean ± SD, n = 4, Student’s t-test, p* < 0.05. d Detection of ROS generation at cellular level in colon cancer cell line, SW480 by intracellular ROS indicator H₂DCFH-DA. Scale bar: 50 μm. e Structure illustration for the substitution of oxygen for sulfur within MoS₂ lattices. f Calculated density of states of MoS₂ QDs show the defects reduce the bandgap. g More sulfur defects induce stronger binding affinity of ³O₂ to MoS₂. h Proposed defect related ¹O₂ generation mechanism of MoS₂ QDs