We report a plasmonic platform based on Au nanospheres for the rapid detection and removal of trace Pd2+ and Pt2+ ions from aqueous systems. Upon exposure to Pd2+, Pt2+, or a mixture of them in the presence of a reductant, surface deposition occurs on the Au nanospheres, leading to pronounced damping of localized surface plasmon resonance that can be monitored by using ultraviolet–visible spectroscopy. By tuning the amount of Au nanospheres, the optical response can be optimized to achieve sensitive detection over a broad concentration range. Structural analyses reveal that the deposited Pd atoms are incorporated into the near-surface region of the nanospheres through interdiffusion, forming an alloyed layer rather than a sharp core–shell boundary. Because the plasmonic response is directly coupled to material uptake, this system enables simultaneous optical detection and removal of platinum-group metals (specifically, Pd2+ and Pt2+ in this work) from the solution.
Wang et al. (Thu,) studied this question.