Enhanced electrochemistry of nanoparticle-embedded polyelectrolyte films: Interfacial electronic coupling and distance dependence

Factors affecting the electronic communication believed to be responsible for the enhanced solution electrochemistry observed at electrodes modified with hybrid polyelectrolyte-nanoparticle (PE-NP) film assemblies were systematically investigated. Specifically, the faradaic current and voltammetric peak splitting recorded for cyclic voltammetry of ferricyanide redox species (Fe(CN)63−/4−) at films constructed with various architectures of citrate-stabilized gold NPs embedded in polyelectrolyte films composed of poly-l-lysine and poly-S-styrene were used to establish the relative importance of both distance and electronic coupling. Layer-by-layer construction of PE-NP films allowed for the position and density of NPs to be varied within the film to assess electronic coupling between particles (interparticle coupling) as well as at the electrode-film interface. The cumulative results observed at these films suggest that, while distance dependence prevails in nearly every case and interparticle coupling can contribute to facilitating the Fe(CN)63−/4− electrochemistry, interfacial electronic coupling of the PE-NP films is of critical importance and decoupling is easily achieved by disengaging NP-electrode interactions.