The remarkable electrocatalytic properties and small size of carbon nanotubes make them ideal for achieving direct electron transfer to proteins, important in understanding their redox properties and in the development of biosensors. Here, we report shortened SWNTs can be aligned normal to an electrode by self-assembly and act as molecular wires to allow electrical communication between the underlying electrode and redox proteins covalently attached to the ends of the SWNTs, in this case, microperoxidase MP-11. The efficiency of the electron transfer through the SWNTs is demonstrated by electrodes modified with tubes cut to different lengths having the same electron-transfer rate constant.

Direct electron transfer between an electrode and the redox active centre of glucose oxidase, flavin adenine dinucleotide (FAD), is probed using carbon nanotube modified gold electrodes. Gold electrodes are first modified with a self-assembled monolayer of cysteamine and then shortened single walled carbon nanotubes (SWNT) are aligned normal to the electrode surface by self-assembly. The electrochemistry of these aligned nanotube electrode arrays is initially investigated using potassium ferricyanide which showed SWNT act as nanoelectrodes with the ends of the tubes more electrochemically active than the walls. Subsequently the nanotubes are plugged into the enzymes in one of two ways. In the first method, native glucose oxidase is covalently attached to the ends of the aligned tubes which allowed close approach to FAD and direct electron transfer to be observed with a rate constant of 0.3 s À1. In the second strategy, FAD was attached to the ends of the tubes and the enzyme reconstituted around the surface immobilized FAD. This latter approach allowed more efficient electron transfer to the FAD with a rate constant of 9 s À1.

The Li/Li+ couple is investigated in the room temperature ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C4mpyrr][NTf2], at a range of temperatures varying from 298 to 318 K.Experiments are conducted using both nickel and platinum microelectrodes. On nickel, a single stripping peak is observed for the stripping of bulk lithium that allowed thermodynamic and kinetic parameters to be extracted via computational simulation. At 298 K, the electrochemical rate constant (k0) ) 1.2 X 10-5 cms-1, the diffusion coefficient (D) ) 4.5 X 10-8 cm2 s-1, the formal potential (E(f)0 ) -3.26 V versus the Fc/Fc+ reference couple, and the transfer coefficient (alpha) = 0.63. On platinum, multiple stripping peaks are observed due to the stripping of Li-Pt alloys in addition to the stripping of bulk lithium. The ratio of the different stripping peaks is found to change with temperature, indicating that Li-Pt alloys are more thermodynamically stable than pure bulk lithium and platinum.

Cyclic voltammetry experiments were conducted using solutions of Na + ions in 12 different ionic liquids (RTILs) on a nickel microelectrode in order to observe the deposition and stripping of metallic sodium. In most of the liquids the potential window was insufficient to observe the formation and removal of bulk sodium, despite the enlargement of some potential windows in the presence of sodium. However, in the ionic liquids) the deposition and stripping peaks for the bulk sodium were observed, allowing simulation of the current-voltage curves and extraction of kinetic and thermodynamic data, notably the electrochemical rate constant, k 0 , and the formal potential, E f 0 , for the Na/Na + couple. Variable temperature measurements also gave quantitative information on the temperature dependence of E f 0 , dE f 0 /dT. Diffusion coefficients for Na + ions in the three RTILs are also reported. All parameters are compared and contrasted with that of the Li/Li + couple, demonstrating that sodium possesses a more positive E f 0 than lithium in the investigated RTILs, although the difference is markedly less than that in solvents such as water or ammonia.

Cyclic voltammetry experiments are carried out using a 0.1 M Li + solution in 12 different room temperature ionic liquids (RTILs), [C 4 mpyrr][NTf 2 ], [C 4 dmim][NTf 2 ], [N 2,1,1,3 ][NTf 2 ], [N 6,2,2,2 ][NTf 2 ], [C 4 mim][OTf], [C 4 mpyrr][N(CN) 2 ], [C 2 mim][NTf 2 ], [P 14,6,6,6 ][FAP], [C 4 py][NTf 2 ], [C 4 mim][PF 6 ], [C 4 mim][NTf 2 ], and [N 1,8,8,8 ][OTf], on a Ni microelectrode to investigate the deposition and stripping of lithium from the electrode surface. [C 4 mpyrr][N(CN) 2 ], [C 2 mim][NTf 2 ], [P 14,6,6,6 ][FAP], [C 4 py][NTf 2 ], [C 4 mim][PF 6 ], [C 4 mim][NTf 2 ], and [N 1,8,8,8 ][OTf] did not have a wide enough potential window to observe the deposition and stripping of bulk lithium. In the experimental data recorded for [C 4 mpyrr][NTf 2 ], [C 4 dmim][NTf 2 ], [N 2,1,1,3 ][NTf 2 ], [N 6,2,2,2 ][NTf 2 ], and [C 4 mim][OTf], a single stripping peak for bulk lithium is seen, and kinetic data for the Li/Li + couple are extracted by comparison with computational simulations. The electrochemical rate constant, k 0 , is found to have values ranging from (1.3 • 10 -6 to 1.2 • 10 -5 ) cm • s -1 . Diffusion coefficients for the Li + ion in these five RTILs are also reported.

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