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Use of Bipolar Electrochemistry to Control Nanofluidics Applications. Bipolar Electrochemistry Concepts Bipolar Electrodeposition onto nanofibers, MWNT’s Preparation and Bipolar Electrodeposition onto CVD Nanopipes Contactless Nanosyringe. Bradley Group: Sundar Babu (postdoc)
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Use of Bipolar Electrochemistry to Control Nanofluidics Applications • Bipolar Electrochemistry Concepts • Bipolar Electrodeposition onto nanofibers, MWNT’s • Preparation and Bipolar Electrodeposition onto CVD Nanopipes • Contactless Nanosyringe Bradley Group: Sundar Babu (postdoc) Patrick Ndungu (graduate student) Guzeliya Korneva (graduate student) Jillian Tromp (undergraduate) Eric Moore (undergraduate)
- + x - + r x = E r cos() Polarization of A Metal Particle in an Electric Field
- + c - + r c = cos-1(Vc / 2E r) Toposelective Electrochemistry
+ M2+ - + M1+ M1 M2 M1 Toposelective Electrodeposition -
Toposome prepared by bipolar electrodeposition of Pd and Au on graphite powder Bradley, J.-C.; Ma, Z. Contactless Electrodeposition of Palladium Catalysts, Angew. Chem. Int. Eng. Ed.1999, vol. 38, 1663.
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. Spatially Coupled Bipolar Electrochemistry (SCBE)
Vc Vc Emin = Emin = L 2r Exploitation of particle aspect ratio to carry out bipolar electrochemistry at sub-micron scale sphere 2r general L
Size and Site Selective Bipolar Electrodeposition of Pd onto Carbon Nanofibers E = 3000 V/cm
A E F B G C H D Bipolar Electrodeposition of Pd onto Carbon Nanofibers 0 s 80 s 10 s 120 s 20 s 240 s 40 s 480 s E = 3000 V/cm
Figure 11: SEM micrograph Cobalt deposited on one tip of MWNT (commercially obtained) by contact less method. Field properties: Intensity 10 kV/cm, ton = 1ms, toff = 24 ms, field time = 25 min Bipolar Electrodeposition of Cobalt on Nanotubes Supported on Polyester Membranes 1, Jean-Claude Bradley, P Ndungu, S Babu. ChemWeb Preprint Server, CPS:chemistry/0304002, 2003, http://preprint.chemweb.com/chemistry/0304002 Bipolar Electrodeposition of Co onto a MWNT
Figure 12: SEM micrograph of Nickel deposited on one tip of MWNT (commercially obtained) by contact less method. Field properties: Intensity 10 kV/cm, ton = 1ms, toff = 24 ms, field time = 25 min Bipolar electrodeposition of nickel on nanotubes supported on polyester membranes 1, Jean-Claude Bradley, P Ndungu, S Babu. ChemWeb Preprint Server, CPS:chemistry/0304001, 2003, http://preprint.chemweb.com/chemistry/0304001 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, ton = 1ms, toff = 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/0311001, 2003, http://preprint.chemweb.com/chemistry/0311001 Bipolar Electrodeposition of Cd onto a MWNT
Quartz tubes to hold the alumina membrane Programmable high temperature furnace Effluent 670oC Alumina membranes stacked between two short quartz tubes Argon 30% C2H4 + 70% He CVD Carbon Nanopipe Synthesis
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/0303002, 2003, http://preprint.chemweb.com/chemistry/0303002 CVD Carbon Nanopipes
Figure 8: SEM micrograph Tin deposited on one tip of nanopipe by contact less method. Field properties: Intensity 10 kV/cm, ton = 1ms, toff = 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/0309001, 2003, http://preprint.chemweb.com/chemistry/0309001 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, ton = 1ms, toff = 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/0312002, 2003, http://preprint.chemweb.com/chemistry/0312002 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, ton = 1ms, toff = 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/0312001, 2003, http://preprint.chemweb.com/chemistry/0312001 Bipolar Electrodeposition of CdS onto CVD nanopipes
(a) (b) (c) (d) Bipolar Electrodeposition of Polypyrrole onto a CVD Nanopipe Bipolar electrodeposition of polypyrrole onto carbon nanotubes 1, Jean-Claude Bradley, P Ndungu, S Babu, J Tromp, N Hackett. ChemWeb Preprint Server, CPS:chemistry/0308001, 2003, http://preprint.chemweb.com/chemistry/0308001
(a) (b) (c) Bipolar Electrodeposition of Polypyrrole onto a CVD Nanopipe 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/0308002, 2003, http://preprint.chemweb.com/chemistry/0308002
(a) (b) Platinum Electrodes (5mm inter-electrode gap) Carbon Nanopipes - + Nuclepore Membrane (pore size 200 nm) (c) (d) Polypyrrole deposited after field application + - - + Polypyrrole deposited after reversing the polarity Contactless Nanosyringe: Step 1 – Introduction of Polypyrrole
Contactless Nanosyringe: Step 2 – Condensation of Water
4.9 Torr 5.3 Torr 4.9 Torr 5.2 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: • Nanopipe blocking • Contactless Nanosyringe