The reaction was carried out for 24 h under bubbled nitrogen, and then gradually a brown
colloidwasformed.
For CdS nanoparticles, 2L of 3-mercaptoacetic acid was added to 100mL of 1mMCdCl2 solution; pH was adjusted to 11 using 0.5M NaOH. The solution was bubbled with nitrogen for 30 min, then 50mL of 1.34mM Na2S was dropwise added.