In this paper, the adsorption characteristics of L-cysteine and L-cystine on CdTe was studied by using the density functional theory. Four stable adsorption configurations were optimized, and their adsorption energies, charge densities, frontier molecular orbits and UV-Vis spectra were calculated. It is found that, when the L-cysteine is adsorbed on CdTe, the adsorption energy is large and the absorption to UV-Vis light is strong, indicating that the adsorption of L-cysteine on CdTe is stable and easy to produce molecular fluorescence. After L-cysteine is converted into L-cystine, the adsorption stability is decreased and the absorption intensity to UV-Vis light is weakened. This study provides theoretical support for the application of L-cysteine mediated synthesis of CdTe QDs fluorescence material in the detection of H2O2 and glucose in biochemical analysis.
