Are you sure about the declaration that after rinsing the Ag nanoparticles charged positively?? I have detected Zeta Potential of Ag prepared in pure deionized water, the value is -20 ! Something wrong, the equipment? This is important to several of my papers. I hope you can give me some proofs about after rinsing, Ag nanoparticles charge positively.
I prepared Silver nanoparticles in pure deionized by laser ablation method, which is similar to a physical method. And when I detect the Zeto Potential, it is really -20. And when I apply an electric field, surprisingly, both on the anode and cathode have some Silver structures. It is strange! The parameters when detection the zeta potential is according to the equipment instrument.