Evaluation of electrochemical properties of nanostructured metal oxide electrodes immersed in redox-inactive organic media.

This paper describes analysis of dropcast nanocrystalline and electrochemically deposited films of NiO and α-FeO as model metal oxide semiconductors immersed in redox-inactive organic electrolyte solutions using electrochemical impedance spectroscopy (EIS). Although the data reported here fit a circuit commonly used to model EIS data of metal oxide electrodes, which comprises an RC circuit nested inside a second RC circuit that is in series with a resistor, our interpretation of the physical meaning of these circuit elements differs from that applied to EIS measurements of metal oxide electrodes immersed in redox-active media. The data presented here are most consistent with an interpretation in which the nested RC circuit represents charge transfer between the metal oxide film and the underlying metal electrode, and the non-nested RC circuit represents the resistance and capacitance associated with formation of a charge-compensating double-layer at the exposed interface between the metal electrode and electrolyte solution.

Physicochemical implications of surface alkylation of high-valent, Lindqvist-type polyoxovanadate-alkoxide clusters.

We report a rare example of the direct alkylation of the surface of a plenary polyoxometalate cluster by leveraging the increased nucleophilicity of vanadium oxide assemblies. Addition of methyl trifluoromethylsulfonate (MeOTf) to the parent polyoxovanadate cluster, [VO(TRIOL)] (TRIOL = tris(hydroxymethyl)methane; R = Me, NO) results in functionalisation of one or two bridging oxide ligands of the cluster core to generate [VO(OMe)(TRIOL)] and [VO(OMe)(TRIOL)], respectively. Comparison of the electronic absorption spectra of the functionalised and unfunctionalised derivatives indicates the decreased overall charge of the complex results in a decrease in the energy required for ligand to metal charge transfer events to occur, while simultaneously mitigating the inductive effects imposed by the capping TRIOL ligand.