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