KVS 2002 Activated Nitrogen Effect in Vertically Aligned CNT Tae-Young Kim, Kwang-Ryeol Lee, Kwang-Yong Eun * Future Technology Research Division, Korea Institute of Science and Technology *Thin Film Technology Research center, Korea Institute of Science and Technology

Carbon Nano-Tubes(CNT) Unique Structure and Properties Suggested Applications Strength: bending strength Young’s modulus: average 1.8TPa Current Conductivity: resistivity<10 -4 Ohm.cm Thermal Conductivity: nearly that of diamond Capillary effect….. Probe tipField emitterElectrode in batteriesConducting wire

Synthesis of CNT Arc discharge, Laser ablation, Plasma CVD, Thermal CVD Thermal CVDThermal CVD  Reaction hydro-carbon gas with metal catalyst particle  Environment gas affect CNT growth

Environment Gas Effect N2N2N2N2 H2H2H2H2 H 2 +N 2 (3:2) 300nm 3.00 ㎛ vol. % C 2 H 2

Growth of Vertically Aligned CNTs 300nm 2.4 vol. % 2.4 vol. % C 2 H 2 in H 2 + N 2 (3:1) 5.00 ㎛ 16.7 vol. % 16.7 vol. % C 2 H 2 in NH 3 H 2 +N 2 vs. NH 3 Environment gas effect

Ni particles after pretreatment for 1h… Environment Gas Effect on Catalyst Activated Nitrogen Pretreatment Reaction(x) H 2, N 2, H 2 +N 2, NH 3 Add C 2 H 2 to the environmental gas H 2 +N 2 vs. NH 3

Activated Nitrogen Effect Activated nitrogen in NH 3 environment play a significant role in the CNT growth kinetics. Suggestion : Activated nitrogen Enhance formation of the graphitic layer on the catalyst Enhance formation of the graphitic layer on the catalyst Enhance the separation of the graphitic layer from the catalyst surface. Enhance the separation of the graphitic layer from the catalyst surface.

Purpose of Present Work Reaction Kinetics and Growth MechanismResearch Reaction Kinetics and Growth Mechanism of Vertically Aligned Carbon nano-tube in the view point of activated nitrogen. When, Where, How does Activated Nitrogen affect CNT growth in overall process?. A.Does nitrogen modify the surface of catalyst in pretreatment process? B.Does nitrogen affect the CNT growth in reaction process?

Experimental Procedure Formation of Catalyst Particles Thermal CVD Tube type reactor with quartz tube (5  800L) at 1 atm. Procedure:  Sample loading after increasing temperature in Ar  Pretreatment  Pretreatment : for 1hr in H 2, N 2, H 2 +N 2, NH 3 Reaction  Reaction :  C 2 H 2 + environmental gas  Cooling in Ar 300nm

Purpose of Present Work Reaction Kinetics and Growth MechanismResearch Reaction Kinetics and Growth Mechanism of Vertically Aligned Carbon nano-tube in the view point of activated nitrogen.

Ni catalystCo catalyst Catalyst Pretreatment Effect NH 3 pretreatment for 4hr, React C 2 H 2 +H 2 Pretreatment Reaction NH 3 H 2 + C 2 H 2

Ni catalyst Co catalyst No pretreatmentH 2 pretreatment Catalyst Pretreatment Effect Pretreatment(x) Reaction NH 3 + C 2 H 2 Pretreatment Reaction H2H2 NH 3 + C 2 H 2

Catalyst Pretreatment Effect Reaction Pretreatment H 2 +C 2 H 2 NH 3 +C 2 H 2 H2H2 X O NH 3 + H 2 O NH 3 XO

Purpose of Present Work Reaction Kinetics and Growth MechanismResearch Reaction Kinetics and Growth Mechanism of Vertically Aligned Carbon nano-tube in the view point of activated nitrogen.

Reaction –Various C 2 H 2 ratio ( X = C 2 H 2 /C 2 H 2 +NH 3,, fixing NH 3 100sccm) Effect of NH 3 Atmosphere in Reaction 0.05 Pretreatment Reaction H2H2 NH 3 + C 2 H

Activated Nitrogen in CNT Fixing NH 3 flux 100sccm

Role of Nitrogen in CNT PRB. VOLUME 59, 5162 PRB, VOLUME 64,

Surface modification of catalyst by activated nitrogen would not affect the vertically aligned CNT growth. Surface modification of catalyst by activated nitrogen would not affect the vertically aligned CNT growth. Activated nitrogen in CNT would have relation with CNT growth rate. Activated nitrogen in CNT would have relation with CNT growth rate. -- Activated nitrogen incorporated into the CNT -- Activated nitrogen incorporated into the CNT would decrease the activation energy of would decrease the activation energy of CNT formation. CNT formation. Conclusion