This result indicates that the fluorescence quenching phenomenon is highly specific.
We attributed the quenching effect to the displacements of surface ligands by H2S.
Previous studies have shown that alkylthiols can rapidly displace weakly bound amines from the surfaces of CdSe/CdS QDs, leading to fluorescence quenching [4,17–19].
Although H2S is not an alkylthiol, it also has a sulfur atom and can act as a Lewis acid. Therefore, it is able to substitute the weakly bound ligands such as TOPO or ODA and quenches the fluorescence.