Suppose that a spherical electrode can be fabricated from a single nano

Chapter 25, Problem 25-15

(choose chapter or problem)

Suppose that a spherical electrode can be fabricated from a single nano onion,C60-C'4D-C'4D-C960-C'500-C,'60-C,940C3840-C4860,shown here. Nano onionscomprise concentric fullerenes of increasingly larger size as indicated in the formula.Assume that the' nano onion has been synthesized with a carbon nanotubetail of sufficient size and strength that it can be electrically connected to a 0.1 flmtungsten needle and that the needle and nanotube tail can be proper! y insulatedso that only the surface of the nano onion is exposed. Given that the radius of the nano onion is 3.17 nm, find the surface area incm', neglecting the area of the nanotube attachment.If the diffusion coefficient of analyte A is 8 X 10-'" m'ls, calculatc the concentrationgradient and the current for A at a concentration of 1.00 mM atthe following times after the application of a voltage at which A is reduced:I X 108s,] X 10"s, 1 X 1O.6s, 1 X 1O-5s,1 X 1O.4s,1 X 10-3s,] X lO"s,1 X 10" s, 1 s, and 10 s.(c) Find the steady-state current.(d) Find the time required for the electrode to achieve steady-state currentfollowing the application of the voltage step.(e) Repeat these calculations for a 3-flm spherical platinum electrode and for aspherical iridium electrode with a surface area of 0.785 mm '.(f) Compare the results for the three electrodes, and discuss any differencesthat you find.