Nanoelectronics and nanoscale electrochemistry: fundaments and applications

Abstract

Chemical covalent attachment of molecules over conductive electrodes and the control of the properties of the nanoscale junction is the state-of-art for molecular electronics and molecular electrochemistry. In the present proposal we suggest to measure the time-dependent electronic features as accessed by impedance methods for fundamental studies and applications of different types of nanoscale junctions in an electrochemical environment. Impedance methods shall be supported by other complementary techniques such as kelvin probe, scanning electrochemical microscopic, Fourier transform infrared spectroscopy and computational simulations. The essence of the problematic is that it has been recently demonstrated that both capacitive and resistive phenomenon involved with electron dynamics throughout molecular-scale junctions embedded in an electrolyte environment are governed by mesoscopic principles. Although this is demonstrated, the mesoscopic physics of nanoelectronics and electrochemistry are marginally exploited up to now. Particularly it has been demonstrated (by our research group) that the electrochemistry of a two-dimensional molecular ensemble made of individual molecular point contacts is a particular case of a quantum resistance-capacitance circuit. The intrinsic electrical current exchange (resonant) between electrochemical accessible sites and the electrode is enlightened by considering quantum resistive-capacitive ensembles (a collection of parallel individual quantum point contacts) in such a way that the electron transfer rate, which govern the rate of electrochemical reactions, is given by k=G/C¼, wherein C¼ is the electrochemical capacitance and G is the conductance accompanying the Landauer formula. Astonishingly this simple equation reconciles molecular electronics and electrochemistry and its usefulness is demonstrated in accessing the energy for charging molecular redox switches (in the Fermi energy of the interface) and thus use these switches as energy transducers in molecular diagnostics. Additionally the concepts were also applied in obtaining the conductance of DNA nanowires (in different chemically designed double strands) and finally in explaining the supercapacitance phenomenon of reduced graphene molecular layers. Even so, the use of specifically designed molecular switches and semiconductive (organic or inorganic) layers under different electric or optical estimulative conditions yet remains to be exploited in both fundamental and experimental features so this constitutes the main goal of the present proposal allied to continuing the investigation of designed switches for molecular diagnostics. For this we are gathering different expertises. (AU)