The obtained hexametaphosphate-capped CdS QDs solution was dialyzed inmembrane tubing with a molecular weight cut-off of 3 KDa againstultrapure water to remove small molecules and ions. The purifiedCdS QDs solution were freeze-dried into powder and measured, andthen the CdS QDs powder was dissolved in aqueous solution againwith 16.3 mg/mL mass concentration.