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3439Nanochemistry

Andreas Borgschulte(andreas.borgschulte@empa.ch)

Introduction

CHE729.1

Mi. 10:15-12:00

Introduction: We are assembled nano-machines! Nanotechnology

History, Definition Visualization of nanostructures Size dependent properties

Preparation of nano structures Bottom-up approach top-down approach theory

Some applications colloids Hydrogen storage catalysis membranes cell biology Nanotoxicity

What is NOT Nanochemistry? What are the scientific questions to be addressed?

Contents of this lecture

Nanotechnology is the manipulation of matter on an atomic and molecular scale. Generally, nanotechnology works with materials, devices, and other structures with at least one dimension sized from 1 to 100 nanometres.

The scanning tunneling microscope, an instrument for imaging surfaces at the atomic level, was developed in 1981 by Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory

K. Eric Drexler developed and popularized the concept of nanotechnology and founded the field of molecular nanotechnology. In 1979, Drexler encountered Richard Feynman's 1959 talk There's Plenty of Room at the Bottom.

Definition / History

Ref. wikipedia

Liquids/gases

Pyrite FeS2

1023

Perovskite CaTiO3

3-mm diamond in eclogite

Diamond

FullereneGraphite

graphene

Carbon nanotubes

• Allotrope of carbon

• Graphite sheet rolled into a tube

• 50,000x smaller than human hair

• Members of fullerene family

(including buckyballs)

www.ewels.info/img/science/nano.html

Single-walled nanotubes

• Capped or uncapped

• All covalent sp2 bonding

• Metallic conductors or semiconductors

• Bundles

• Defects – points for reaction

http://www.msm.cam.ac.uk/polymer/research/nanointroCNT.html

Multi-walled nanotubes

• 63GPa tensile strength(steel 1.2GPa)

• Inner tubes slide without friction

Picture credit: Alexander Aius, Wikipedia https://www.youtube.com/watch?v=O1WpE5ntqbQ

Graphene – the new Wonder material

Strength of graphene Graphene has a breaking strength of 42N/m, which is more than 100 times

stronger than steel Electrical conductivity of graphene

The sheet conductivity of a 2D material is given by . The mobility is theoretically limited to μ=200,000 cm2V−1s−1 by acoustic phonons at a carrier density of n=1012 cm−2. The 2D sheet resistivity, also called the resistance per square, is then 31 Ω. Our fictional hammock measuring 1m2 would thus have a resistance of 31 Ω. σ=enμ

Using the layer thickness we get a bulk conductivity of 0.96x106 Ω-1cm-1 for graphene. This is somewhat higher than the conductivity of copper which is 0.60x106 Ω-1cm-1.

Thermal conductivity The thermal conductivity of graphene is dominated by phonons and has

been measured to be approximately 5000 Wm−1K−1. Copper at room temperature has a thermal conductivity of 401 Wm−1K−1.

Background information Noble price in Physics 2010 https://www.nobelprize.org/nobel_prizes/physics/laureates/2010/advanced-physicsprize2010.pdf

The intrinsic resistivity of graphene sheets would be 10−6 Ω⋅cm. This is less than the resistivity of silver.

Electrons behave like a wave…

Akin Akturk and Neil Goldsman, J. Appl. Phys. 103, 053702 (2008); A. H. Castro Neto et al., Rev. Mod. Phys., Vol. 81, 109 (2009)

∗12 ⋯

Massless Dirac quasiparticles in graphene

Oleg Shpy

Band structure in crystalline solids: Bloch functions

airRr /2exp)()( 0

Theory

k = 0

k = /a

k = 0

k = 0 k = /a

E(k)

E0

),()(2

2

rrrRVm

Schrödinger equation solvable for limited number of atoms

N ~ 1023

N < 103

M. D. Hanwell

Nanomaterials102 … 105

atoms

J. Cai, P. Ruffieux, R. Jaafar, M. Bieri, T. Braun, S. Blankenburg, M. Muoth, A.P. Seitsonen, M. Saleh, X. Feng, K. Müllen, R. Fasel, Nature, 466, 470-473 (2010)

Nanoribbons for graphene transistors

Baringhaus, J.; Ruan, M.; Edler, F.; Tejeda, A.; Sicot, M.; Taleb-Ibrahimi, A.; Li, A. P.; Jiang, Z.; Conrad, E. H.; Berger, C.; Tegenkamp, C.; De Heer, W. A. Nature 506, 349–354 (2014)

Memory Chip

H2 combustion needs 600°C without, proceeds at RT with Pt catalyst

Catalysis of hydrogen combustion

Döbereiner Cigar lighter (1823)

H + H (E = 2.4 eV)

MHMH *22

OHOHOH 222 2*2*42

Catalytic hydrogen burner (Empa 2009)

Pt-nano particles on a ceramics

Surface Reaction

Hydrogen dissociation on d-metals

Solid–liquid interface: Electrochemical Double layer

pote

ntia

ldistance

-

water

solid +

+

+

+

+

+

nm

mol/lIIeNTk

A

BrD

34.02 2

01

xxTkB

expze with

Debye length

T. Cosgrove, Colloid Science, Principles, methods, and applications, Wiley 2010;

-+-

-0

-0

The mystery of electrochemistry

kTUEekj /0 1

H

H+

H

H

H2O-H+

H2O-H+

H2O-H+

H2Oe-e-

H2O-H+

H2

H+ H3O+ch

emic

al p

oten

tial

reaction coordinate

U

U

E

kTUUEekj /0 '

The hydrogen electrode: Butler‐Volmer equation

H2

Pt-electrode

Ubjj )(loglog 0

G

reaction coordinate

free

ener

gy

21111)( eRr

efGstatopt

Marcus‐Theory of the charge transfer

TkGTkB

4

exp)(20

Transition-state Theory

electrostatic contribution

4

20GG + chemical

contribution G0

metalsphere

metalsphere

Ion

G

e

free

ener

gy

R.A. MarcusNobel price 1992

TkGTkB

4

exp)(20

00 IG

0IIG

0IIIG

G

q=e

reactant / Product I/II/III

Experimental confirmation of Marcus theory

R. Marcus, Angew. Chem. lnt. Ed. Engl. 1993, 32. 1111

Variation of G0 at constant

-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2

1E9

1E10

1E11

1E12

1E13

k (s

-1)

G (eV)

ln ∝∆

4 ∙

0.5 0.4 0.3 0.2 0.1 0.0 -0.10.1

1

10

100

j (m

A/c

m2 )

U = G (eV)

ln ∝ 2 ln

+- +

inverted region

Electron transfer between molecules ~ Electrodes

S. Murphy, et al., J. Org. Chem., 60, 2411, 1995; M. H. Miles, et al. J. Electrochem. Soc., Bd. 123, p. 332, 1976.

∝∆2

B

Reorganization energy

sv

The outer part corresponds to the energy cost from the solvent response.

The inner part corresponds to the energy cost due to geometry modifications to go from a neutral to a charged geometry and vice versa.

0 50 100 150 2001.4

1.6

1.8

2.0

2.2

volta

ge (V

)

current density (mA cm-2)

TkGTkB

4

exp)(20

of the first electron transfer only ~0.25 eV out of an overall excitation energy of 1.38 eV

R. Marcus, Angew. Chem. lnt. Ed. Engl. 1993, 32. 1111

Mitochondria_360p Kopie.mov

Biology takes place in nano-structures

membrane thickness ~10 nm

mitochondrium

Simplified spatial scheme of photosynthesis

ADP+P

ATP

4H + O+2

2 H O2

H+ NADP + H+

NADPH

3H+

OEC

HECP680/Q PQ

PC

P700/Q

cyto

chro

me

ATP

synt

hase

lumen

stroma

Lurgi, Zdansky-Lonza pressure electrolysis: (a) Bipolar electrodes, dimple plate cell partition; (b) Pre-electrodes in the form of nets on both sides of asbestos diaphragms ;(c) Asbestos diaphragms; (d) Cell frame;

(Häussinger P., et al., 2006)

gas separation by membranesl = 1mm

Alkaline water electrolyzers: electrolyte/membrane

+ -H2O2

Mg1 Mg1

Mg1Mg1 Mg1

SiO4SiO4

Mg2Mg2

SiO4 SiO4

Mg1 Mg1

Mg1Mg1 Mg1

Mg2Mg2

Mg2 Mg2

SiO4

Mg2

SiO4

Mg1Mg1

Mg1Mg1 Mg1

SiO4SiO4

Mg2Mg2

SiO4 SiO4

Mg1 Mg1

Mg1Mg1 Mg1

Mg2Mg2

SiO4

Mg2

SiO4

Mg1Mg1

Mg1 Mg1Mg1

http://webmineral.com/

Olivine, (Mg,Fe)2SiO4)

Main unit for all silicates :

O

Si

SiO4

SiO4

SiO4

SiO4

SiO4

SiO4

SiO4

SiO4

SiO4

Quartz SiO2

Chrysotile(Asbestos):Mg3Si2O5(OH)4

Betechtin, Mineralogy, 1951

Top: SEM image of a chrysotile, Mg3Si2O5(OH)4, one of the asbestos minerals) fiber bundle. Bottom: through the fiber bundle (Ref: Grobety et al.,)

BO

NBO

Pyroxene, (Fe, Ca,Mg)2Si2O6

Silicates: crystal structure

However, the physical shape of material can seriously affect its toxicity

Asbestos

Serpentine– flat sheets of atoms, harmless

Chrysotile– nano-scale tubes

One should treat these new nano-materials with caution

Nano-structured membranes have superior properties

http://whatisasbestosis.com/risks-of-asbestos-exposure/

Nanotoxicity

Empa Nanosafety Research: Human macrophage exposed to Hematite-Nano particles (70 nm). SEM

band-aid coated with Ag nano particles (Empa)

C. A. Poland et al. nature nanotechnology 3, 423 (2008)

‘frustrated’ phagocytosis of carbon nanotubes by peritoneal macrophages.

Asbestos nano fibres cause lung cancer

Nanotoxicity of Au-particles

All nanoparticles within the 2–100 nm size range were found to alter signalling processes essential for basic cell functions (including cell death), 40- and 50-nm nanoparticles demonstrated the greatest effect.

W. Jiang et al. nature nanotechnology 3, 145 (2008)

Buckyball(~1nm)DNA

(~2nm diameter)

Red blood cells(~2-5μm)

Hair (~60-120μm)Virus(10-300nm)

Gold atom(135pm)

10mm

1mm

0.1mm

0.01mm

0.001mm, 1μm (1000nm)

0.1μm (100nm)

0.01μm (10nm)

1nm

Ult

ravi

olet

Infr

ared

Mic

row

ave

0.1nm

10-2m

10-3m

10-4m

10-5m

10-6m

10-7m

10-8m

10-9m

10-10m

X-ra

y

Courtesy ZoeSchnepp

Bio-nano machines (<10 nm) Ag-nanoparticles(1-100 nm)

colloids, (micro-) emulsion phase diagrams, stability Ostwald ripening, coalescence electrochemical double layer,

zeta-potential rheology Aerosols

Tyndall effect

Colloids

pics_: Wikipedia

Wave length of visible light: 400 – 800 nm

NAd

2

resolution limit of the microscope

Can we see nano structures?

optics: d ~ 200 nmelectron microscope d < 1 nm

JEOL 2200FS TEM/STEMHigh-resolution and analytical STEM/TEMTomographyPoint resolution TEM 0.23 nmResolution STEM 0.16 nm

Ernst Karl Abbe

Nano-structure of a Hydrogen combustion catalyst

A. Fernández et al., Appl. Catal. B (2016)

Scanning Probe Microscopy

Measuring physical interaction (z)

Use it as a control parameter to map the surface

Force (AFM) Tunneling current (STM) Capacity (SCAM) Light (SNOM) Thermal properties

+

+- -

+-

s

R

1st images of Si (111): Binnig and Rohrer 1982

Tunneling current in STM

U I

surface tip

vacuummetal metal

dEF

Atomic resolution of ||2 (no atoms!)

Atoms at the surface of a carbon nanotube

Size and surface area effects 1 nm – 100 nm Fundamental materials properties remain the same but size, shape and surface area alter some behaviors such as work function, solubility, chemical potential, contaminate sorption

Critical Size and Characteristic Length Scale Interesting or unusual properties because the size of the system approaches some critical length (includes quantum effects). Many characteristics of material may have normal or nearly normalbehavior

New (Non-extensive) Properties Systems not large enough to have extensive properties. Particles become effectively polymorphs of “bulk” materials and statistical homogeneity may not be valid.

Size dependent properties

0.1

1

10

100

1000

spec

ific

surf

ace

area

[m2 g

-1]

10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3

characteristic length [m]

1020

1015

1010

105

100

number of atom

s per particle

C

Pd

ratio surface atoms / bulk atoms

rVm 2

contribution by surface energy significant below 3 nm

Size dependent properties

45

Size dependent properties

Melting Temperature of Au Clusters

Ph. Buffat and J.-P. Borel, Phys. Rev. A 13, 6 1976), pp. 2287-2298

Au~800

24 Å

rHV

TT m

2

Catalytic properties of Au Clusters

X. Lai, D. W. Goodman, J. Molecular Catalysis A: 162, (2

Size dependent properties

Optical properties of Au Clusters

Lycurgus cup(Roman times)

Illuminated from behind, the gold nanoparticle-containing dichroic glass that the cup is made from appears deep red in color.

window glass(Medieval times)

Maksym V. Kovalenko ,* Erich Kaufmann , Dietmar Pachinger , Jürgen Roither , Martin Huber , Julian Stangl , Günter Hesser,Friedrich Schäffler , and Wolfgang Heiss, J. Am. Chem. Soc., 2006, 128 (11), pp 3516–3517

Angshuman Nag, Maksym V. Kovalenko, Jong-Soo Lee, Wenyong Liu, Boris Spokoyny, and Dmitri V. Talapin, J. Am. Chem. Soc., 2011, 133 (27), pp 10612–10620

Size dependent properties

Colloidal HgTe Nanocrystals with Widely Tunable Narrow Band Gap Energies: From Telecommunications to Molecular Vibrations

Metal-free Inorganic Ligands for Colloidal Nanocrystals: S2–, HS–, Se2–, HSe–, Te2–, HTe–, TeS32–, OH-, and NH2– as Surface Ligands

http://www.nanoscience.at

Preparation of nano structures

The ‘top-down’ approach

The ‘bottom-up’ approach

structuring matter“Nanotechnology”

self-assembly“Nanochemistry”

The quantum corral reef -An academic gadget (Eigler et al. IBM)

Nanostructuring on atomic length scale (Top-down)

G. Medeiros-Ribeiro et al., Phys. Rev. B 58, 3533 (1998)

external transport

homogeneous nuleationheterogeneous

adsorption-desorption

Cluster-kinetics

surface-diffusion

growth- kinetics

Nanostructuring by thin film technology

physical vapor deposition (bottom-up) chemical vapor deposition (bottom-up) sputtering (bottom-up) electrochemistry (bottom-up) ion etching (top-down) (photo-)lithography (top-down)

0 10 20 30 400

10

20

30

40

50

Ti(C,N)-phase Ni-phase

sche

rrer

cry

stal

lite

size

[nm

]

m illing time [h]

Nanostructuring by ball milling (Top-down)

Courtesy Nico Eigen

Preparation: The ‘bottom-up’ approach

Small molecules or particles pre-designed to self assemble into larger, organised structures

e.g. surfactants Hydrophilic head group

Hydrophobic tail

Spherical micelle

water

oil

oil

oil

oil oil

Courtesy Zoe S h

http://www.biologycorner.com/resources/DNA-colored.gif

Sugar phosphate

backbone

Bottom-up approach in nature

Guanine Cytosine

Adenine Thymine

Courtesy Zoe S h

relevant biosystem can be grown/studied in labs

Nano particles in Freshwater Biofilms

Stream biofilm inhabitants. By D. C. Sigee

http://www.iees.ch/EcoEng061/EcoEng061 Rijstenb

Silver ions are bactericide

EPS reduces Ag + and stabilizes Ag NPs.

Courtesy Olga Sambalova

400 500 600 700

0.2

0.4

0.6

0.8

1.0

1.2

Abs

orba

nce

Wavelength [nm]

After 0 h After 1 h After 10 h After 20 h

+++++++++++++++++++++

++++++++++++++++++++++++++

++++++++++++++++++

- - - - - - -- - - - - - - - - -

- - - - - - - - - - - -- - - - - - - - - - -

- - - - - - - - -

- - - - - - -- - - - - - - - - -

- - - - - - - - - - - -- - - - - - - - - - -

- - - - - - - - -

- - - - - - -- - - - - - - - - -

- - - - - - - - - - - -- - - - - - - - - - -

- - - - - - - - -

+

=

plasmon oscillation

discrete positive nuclei positive background

free electron cloud

jellium

UV-VIS on Silver-Nanoparticles

Interaction depends on size of the Nano particles

principles of existing / future technologies

What are the scientific questions to be addressed?

chemistry

biology

physics

chemical engineering

principles of existing / future technologies Underlying science / methods

What are the scientific questions to be addressed?

computer science

surface science / microscopy

experimental methods, tools, concepts

principles of existing / future technologies Underlying science / methods What are the problems/limits of these technologies?

What are the scientific questions to be addressed?

applications

materials properties

safety/cost/abundancepicture by Zoe Schnepp

principles of existing / future technologies Underlying science / methods What are the problems/limits of these technologies? future visions

What are the scientific questions to be addressed?

artificial photosynthesis

nanocar

24.02.2016Introduction 02.03.2016Measurement of Nanostructures I 09.03.2016Measurement of Nanostructures II 16.03.2016Optical Properties 23.03.2016Surface Science I 06.04.2016Surface Science II 13.04.2016Preparation of nano structures I 20.04.2016Preparation of nano structures II 27.04.2016Applications I: Catalysis 04.05.2016Applications II: Energy 11.05.2016Applications III: Wetting, Colloids 18.05.2016Theory 25.05.2016cell biology / Nanotoxicity 01.06.2016seminar talks

Contents of lecture NanoChemistry

andreas.borgschulte@empa.ch

Ludovico Cademartiri and Geoffrey A. Ozin, Concepts of nanochemistry, Wiley VCH Weinheim 2009

Terence Cosgrove (Ed.), Colloid Science, principles, methods and Applications, Wiley 2010

Lecture sheets download: http://www.chem.uzh.ch/en/study/old/documents/master/che834.html

Literature