Use of Bipolar Electrochemistry to Control Nanofluidics Applications Bradley Group: Sundar Babu (postdoc) Patrick Ndungu (graduate student) Guzeliya Korneva (graduate student) Jillian Tromp (undergraduate) Eric Moore (undergraduate) 1.Bipolar Electrochemistry Concepts 2.Bipolar Electrodeposition onto nanofibers, MWNT’s 3.Preparation and Bipolar Electrodeposition onto CVD Nanopipes 4.Contactless Nanosyringe

Polarization of A Metal Particle in an Electric Field  r x  x = E r cos(  )

Toposelective Electrochemistry  c = cos -1 (V c / 2E r) cc r

Toposelective Electrodeposition M1+M1+ M1M1 M2+M2+ M1M1 M2M2

Bradley, J.-C.; Ma, Z. Contactless Electrodeposition of Palladium Catalysts, Angew. Chem. Int. Eng. Ed. 1999, vol. 38, Toposome prepared by bipolar electrodeposition of Pd and Au on graphite powder

Spatially Coupled Bipolar Electrochemistry (SCBE) Bradley, J.-C.; Chen, H.-M.; Crawford, J.; Eckert, J; Ernazarova, K.; Kurzeja, T.; Lin, T.; McGee, M.; Nadler, W.; Stephens, S.G. Nature, 1997, vol. 389, 268.

Exploitation of particle aspect ratio to carry out bipolar electrochemistry at sub-micron scale 2r L sphere E min = VcVc 2r E min = VcVc L general

E = 3000 V/cm Size and Site Selective Bipolar Electrodeposition of Pd onto Carbon Nanofibers

E F H G D A B C 0 s 10 s 20 s 40 s 80 s 120 s 240 s 480 s E = 3000 V/cm Bipolar Electrodeposition of Pd onto Carbon Nanofibers

Bipolar Electrodeposition of Cobalt on Nanotubes Supported on Polyester Membranes 1, Jean-Claude Bradley, P Ndungu, S Babu. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Figure 11: SEM micrograph Cobalt deposited on one tip of MWNT (commercially obtained) by contact less method. Field properties: Intensity 10 kV/cm, t on = 1ms, t off = 24 ms, field time = 25 min Bipolar Electrodeposition of Co onto a MWNT

Bipolar electrodeposition of nickel on nanotubes supported on polyester membranes 1, Jean-Claude Bradley, P Ndungu, S Babu. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Figure 12: SEM micrograph of Nickel deposited on one tip of MWNT (commercially obtained) by contact less method. Field properties: Intensity 10 kV/cm, t on = 1ms, t off = 24 ms, field time = 25 min Bipolar Electrodeposition of Ni onto a MWNT

Figure 10: SEM micrograph Cadmium deposited on one tip of MWNT (commercially obtained) by contact less method. Field properties: Intensity 10 kV/cm, t on = 1ms, t off = 24 ms, field time = 60sec Bipolar Electrodeposition of Cadmium onto one tip of a Carbon Nanotube, Jean-Claude Bradley, P Ndungu, S Babu, J Tromp, N Hackett. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Bipolar Electrodeposition of Cd onto a MWNT

CVD Carbon Nanopipe Synthesis 670 o C Argon 30% C 2 H % He Effluent Programmable high temperature furnace Quartz tubes to hold the alumina membrane Alumina membranes stacked between two short quartz tubes

SEM micrographs of CVD nanopipe obtained by CVD of 30%C2H4 + 70% He at 670oC inside the pores of alumina membrane. The Alumina template was removed by sonicating the membrane in 1M NaOH for 90 min. Nanotube Synthesis Using Alumina Template (a4), Jean-Claude Bradley, S Babu, P Ndungu, A Nikitin, Y Gogotsi. ChemWeb Preprint Server, CPS:chemistry/ , 2003, CVD Carbon Nanopipes

Figure 8: SEM micrograph Tin deposited on one tip of nanopipe by contact less method. Field properties: Intensity 10 kV/cm, t on = 1ms, t off = 24 ms, field time = 10sec Bipolar Electrodeposition of Tin onto one tip of a Carbon Nanotube 1, Jean-Claude Bradley, P Ndungu, S Babu, J Tromp, N Hackett. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Bipolar Electrodeposition of Sn onto a CVD nanopipe

Figure 9: SEM micrograph of Zinc deposited on one tip of nanopipe by contact less method. Field properties: Intensity 6 kV/cm, t on = 1ms, t off = 24 ms, field time = 40sec Bipolar Electrodeposition of Zinc onto one tip of a Carbon Nanotube 1 Jean-Claude Bradley, P Ndungu, S Babu, G Korneva, J Tromp, E Moore. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Bipolar Electrodeposition of Zn onto a CVD nanopipe

Figure 13: SEM micrograph of Cadmium sulfide deposited on one tip of nanopipe. Field properties: Intensity 9 kV/cm, t on = 1ms, t off = 24 ms, field time = 20 sec Bipolar Electrodeposition of Cadmium Sulfide onto one tip of a Carbon Nanotube 1, Jean-Claude Bradley, P Ndungu, S Babu, J Tromp, N Hackett, E Moore. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Bipolar Electrodeposition of CdS onto CVD nanopipes

(c)(d) (b)(a) Bipolar electrodeposition of polypyrrole onto carbon nanotubes 1, Jean-Claude Bradley, P Ndungu, S Babu, J Tromp, N Hackett. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Bipolar Electrodeposition of Polypyrrole onto a CVD Nanopipe

(a)(b) (c) Bipolar Electrodeposition of Polypyrrole onto both ends of a Carbon Nanotube 1, Jean-Claude Bradley, P Ndungu, S Babu, J Tromp, N Hackett. ChemWeb Preprint Server, CPS:chemistry/ , 2003, Bipolar Electrodeposition of Polypyrrole onto a CVD Nanopipe

(b)(a) Nuclepore Membrane (pore size 200 nm) Platinum Electrodes (5mm inter-electrode gap) Carbon Nanopipes (c) Polypyrrole deposited after field application (d) Polypyrrole deposited after reversing the polarity Contactless Nanosyringe: Step 1 – Introduction of Polypyrrole

Contactless Nanosyringe: Step 2 – Condensation of Water

4.9 Torr5.2 Torr 5.3 Torr4.9 Torr Polypyrrole Mediated Injection of Water into a Nanopipe Condensation of Water into a Nanopipe without Polypyrrole

Conclusions Bipolar Electrochemistry can be exploited as a control element for nanofluidics applications: 1)Nanopipe blocking 2)Contactless Nanosyringe