The use of copper-doped Fe nanoaggregates silanized with organic sulfur as bis-(triethoxy silyl propyl)tetra sulfide has been investigated for the capture of elemental mercury (Hg-0) from the vapor phase for potential power plant applications. Silanization procedures resulted in 70% deposition of the targeted sulfur level, with particles containing approximately 4 wt % S. The addition of copper was found to increase the fixed-bed (total) capacity of this type of sorbent from 170 +/- 20 mu g Hg center dot g sorbent(-1) with no copper doping to 2730 +/- 80 mu g Hg center dot g sorbent(-1) at 1.2 wt % Cu. When no S is deposited, the capacity of Fe/Cu nanoaggregates was only 180 mu g Hg center dot g sorbent(-1). These findings suggest that a combined Cu-S mechanism is responsible for Hg capture. Moving-bed (injection) testing of the Fe-based sorbents in a simulated flue gas stream showed that the 1.2 wt % Cu sample was able to achieve significant removal of the Hg. At a modest sorbent injection rate of 3.6 x 10(-3) g center dot L-1 center dot h(-1), this material showed a steady-state removal capacity of 107.5 mu g Hg center dot g sorbent(-1) for an inlet concentration of 17.8 mu g center dot m(-3). On the basis of only 4% usage of the total capacity during single-pass injection, it might be beneficial to develop methods to separate and recycle these materials to reduce power plant operation costs for Hg emissions control.