Label-free tungsten disulfide quantum dots as a fluorescent sensing platform for highly efficient detection of copper (II) ions
Zhao Xuan, He Da-Wei †, Wang Yong-Sheng ‡, Hu Yin, Fu Chen, Li Xue
       

(color online) (a) Absorption and PL emission spectra of WS2 QDs (inset: calculated band gap energy of WS2 QDs). (b) PL emission spectra of the WS2 QDs obtained under excitations from 280 nm to 390 nm with 10-nm increase. The high resolution XPS survey spectra of the as-prepared WS2 QDs. (c) W 4f and (d) S 2p spectra.