Nitrate reduction catalyzed by nanocomposite layer of Ag and Pb on Au(1 1 1)

The underpotential deposition (UPD) of silver and lead on Au(1 1 1) was performed sequentially to produce a thin composite layer. Ag was deposited underpotentially in 1 mM Ag2SO4 and 0.1 M H2SO4 at 0.400 V and 0.010 V vs. Ag wire. The results of cyclic voltammetry carried out on this Ag/Au(1 1 1) electrode in a Pb2+ electrolyte with 0.1 M HClO4 indicated contributions from both Au and Ag substrates. In situ STM images showed that the UPD of Pb on Ag/Au(1 1 1) had an unusual multilayer morphology. Cyclic Voltammetry was also used to demonstrate the stability and presence of the Ag adlayer in the Pb2+ electrolyte. In the presence of sodium nitrate, this composite system exhibits a catalytic effect on nitrate reduction that is not observed for Au(1 1 1), Ag/Au(1 1 1), Pb/Au(1 1 1), Ag(1 1 1), or Pb/Ag(1 1 1). Our results demonstrate that the Ag–Pb/Au(1 1 1) composite system has an enhanced catalytic effect on nitrate reduction.