The 7 th Korea-U.S. Nano Forum Block Copolymer Based Hybrid Nanostructured Materials As Key Elements In Green Nanotechnology Dong Ha Kim Department of Chemistry and Nano Science, Ewha Womans University 2010. 04. 05 1
Overview Self-Assembly Large area patterning Ordered nanostructure Metal/Semiconductor Charge/energy transfer Bandgap engineering Field enhancement Multifunctional Low-Dimension Hybrid Nanoplasmon Materials Surface Plasmon LSPR Prism coupling Green Nanotech. ET Photocatalysis Energy Devices Optical Biosensor BT High Sensitivity High Selectivity Multiplex Sensing 2
laser light detector Light Emission Protein Nanoarray Lithography Optical Waveguide Hybrid Carbon Nanotube Ag TiO2 Hybrid Metal/Semiconductor TiO2 Nanobowl Functional Multilayer Photonic Band Gap Material ZnO Nanoring 2D Nanoparticle Array substrate substrate
Nanostructured Carbons Lithography Protein Nanoarray PS Si 3 N 4 Si Nano Lett. 2008, 8, 3993 J. Mater. Chem., submitted Bio Nano Lett. 2007, 7, 1516 Nanotechnology 2006, 17, 2122 Nanostructured TiO 2 (ZnO) laser light SPR Sensing detector Nano Lett. 2009, 9, 2384 J. Mater. Chem. 2009, 19, 2006 Adv. Mater 2005, 17, 2442 J. Phys. Chem. B 2006, 110, 15381 Macromol. Res. 2007, 15, 211 J. Mater. Chem. 2010, 20, 677 J. Mater. Chem. 2009, 19, 7245 Chem. Commun. 2009, 1091-1093 Chem. Mater. 2008, 20, 6041 Chem. Mater. 2008, 20, 1200 Soft Matter 2008, 4, 515 Macromol. Rapid Commun. 2008, 28, 2055 ChemPhysChem 2006, 7, 370 Adv. Funct. Mater. 2005, 15, 1160 Langmuir, 2005, 21, 5212 Macromol. Rapid Commun. 2005, 26, 1173 Nano Lett. 2004, 4, 1841 Adv. Funct. Mater. 2008, 18, 3148 Biomacromolecules 2009, 10, 1061 Light Emission Appl. Phys. Lett. 2008, 93, 183303 Chem. Mater. 2008, 20, 6041
Photocatalyst e e e e e e E F hv h E F Au TiO 2 (Surface Plasmon Resonance) SPR - 1.63 ev hv CB ------ 0.8 ev --- Au E f = 0.75 ev OH OH- VB + + + ZnO -2.48 ev 5
Pt/TiO 2 Nanohybrids Small amount of TiO 2 0.8 x 0.8 cm UV light irradiation spin casting in toluene PS 20k -b-peo 6.5k Pt precursor TiO 2 sol-gel Si wafer UV light irradiation (7h) 0.8 x 0.8 cm 4 ml 10 ppm p-np(aq) Excess amount of TiO 2 UV-Vis absorbance measurement 6
Pt/TiO 2 10 vol % 40 vol % 80 vol % 0.5 μm After UV exposure 7
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Carbon-based Electrodes 9
Electrodes in Fuel Cell Anode: Fuel oxidation reaction Cathode: Oxygen reduction reaction DMFC: CH 3 OH + H 2 O CO 2 + 6H + + 6e - DMFC: 1 ½ O 2 + 6H+ + 6e- 3H 2 O H 2 FC: H 2 2H + + 2e - H 2 FC: ½ O 2 + 2H + + 2e - H 2 O Pt (+Ru) Nanocatalysts in Carbon (+TiO 2 ) Matrix Pt (+Pd, Ni, Co) Nanocatalysts in Carbon (+TiO 2 ) Matrix Overall reaction DMFC: CH 3 OH + 1 ½ O 2 + H 2 O CO 2 + 3H 2 O H 2 FC: H 2 + ½ O 2 H 2 O 10
Pt/C or Pd/C Hybrids in Electrocatalysis High dispersion of Pt on porous carbon gives rise topromising electrocatalytic activity for O 2 reduction, which could prove to be relevant for fuel-cell technologies. 1-D carbon nanofiber loaded with Pt nanoparticles had high electrocatalytic methanol oxidation reaction due to its high mass transport and electron transport. S. H. Joo, Nature 2001, 412, 169 G. Zhao, J. Phys. Chem. C 2008, 112, 1028 The Pt nanocube/carbon catalyst with dominant {100} faces showed lower onset potential and higher current density for methanol electrooxidation than the polycrystalline Pt nanocatalyst. Graphene nanosheets were expected as a new carbon support material modi-fying catalytic properties of Pt fuel cell catalysts. S. B. Han, Electrochem. Commun. 2008, 10, 1044 11
For methanol electrooxidation, the polygonal Pd/C shows improved current-density and less accumulation of residues. The polygonal Pd/C exhibits an excellent stability in comparison with commercial Pd/C. Pd/MWCNT (> Pd/C > Pd/ACF) electrocatalyst showed the highest activity for ethanol oxidation in alkaline media. The results indicated that the support would significantly influence the catalytic activities. Y. W. Lee, Electrochem. Commun. 2009, 11, 1968 H.T. Zheng, J. Power Sources 2006, 163, 371 The Pd/coin-like hollow carbon (CHC) electrocatalyst gave a enhanced performance for MeOH oxidation because the micrometer sized CHCs significantly reduced the liquid sealing effect. The activities of alcohol oxidation on Pd on carbonized pulverized PAA electro-catalyst are higher than that on Pd/C. Electrodes prepared by Pd/CPAA showed a porous structure, resulting in a high active surface area. D. Yuan, Electrochem. Commun. 2007, 9, 2473 Z. Wang, Electrochem. Commun. 2006, 8, 1764 12
Scheme to Pt-Ru/C Nano-Architectures + Pt precursor Ru precursor PtRu alloy in toluene spin coating PS 41k -b-p4vp 17k Pt Ru precursor Multilayered Alloy Metal/C Nanostructures 13
Pt/C 1 layered 500 nm 5 layered 500 nm
5 layered Pt/C in HClO 4 5 layered Pt/C in HClO 4 + MeOH 5 layered Pt-Ru/C in HClO 4 5 layered Pt-Ru/C in HClO 4 + MeOH
Summary What have been done: Block copolymer self-assembly for tailored hybrid nanostructures Direct carbonization route to hybrid carbon nanostructures Metal/TiO 2 or Carbon/TiO 2 as visible light active photocatalysts Pt-Ru/C based electrocatalyst for fuel cell anodes Further discussions: Candidates for cathode? Universal paradigm for the design of elements in energy devices 16
Acknowledgements Collaborators Dr. Dinakaran Kannaiyan, Postdoctoral Researcher Saji Thomas Kochuveedu, Yoon Hee Jang, Ph.D. Candidate Min-Ah Cha, Yu Jin Jang, Jieun Lee, Ji Yong Lee, Juyon Lee, M.S. Candidate Finantial Supports Brain Korea 21 National Research Foundation Seoul Research and Business Center Brain Pool Research Fellowship Ewha Global Partnership Program Polymer Nanohybrid Materials Lab http://nano.ewha.ac.kr/~polykim 17