st
National Centre for Catalysis Research
INDIAN INSTITUTE OF TECHNOLOGY MADRAS
APRIL 2010

Title
Periodic properties of elements
Nomenclature and isomerism of coordination compounds
Nuclear reactions and carbon dating
Types of hybridization and geometry of molecules
Chemical equilibrium – Le Chatliers principle
Colloids and applications
Faradays laws and Kohlrausch’s law
Extraction of Metals
Spontaneous and non spontaneous reactions
Corrosion and its prevention
Properties and packing in solids
Wave equation and its significance
Petroleum and Petro chemicals

Bonding in molecules
Conventional concepts of bonding has to undergo change – Why?
Behaviour of molecules and reactivity of molecules – what is so special selectivity?
Geometry of the molecules, manifestations of molecules – functioning of molecules.
Architecture in solids – transport restrictions
Electrochemistry turns chemistry to be fully green
Behaviour of electrons – responsible for the science that is usually generated
Nuclear structure – evolution period and also energy conversion process

th

• Assembly appears to be the order these days – these assembly can arise out of weak interactions
• Weak interactions may be hydrogen bonding, van der waals forces and simple over lap of the least amount of charge cloud.
• Assembly assumes particular geometries, like helical structure, nano-coils, nano-twisted wires and many others – these resemble the bio-molecules

What is Green Chemistry?
It is better to prevent waste than to clear it up afterwards
% Atom economy is the new % yield
The strive towards the perfect synthesis
Benign by design
Environmentally friendly and economically sound?!?

The Twelve Principles of Green Chemistry
•
It is better to prevent waste than to treat or clean up waste after it is formed.
• Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product
• Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment
• Chemical products should be designed to preserve the efficacy of function whilst reducing toxicity
• The use of auxiliary substances (e.g. solvents) should be made unnecessary wherever possible and innocuous where used
• Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be carried out at ambient temperature and pressure
• A raw material of feedstock should be renewable rather than depleting wherever technically and economically possible
• Unnecessary derivatization (e.g. protecting groups) should be avoided wherever possible
• Catalytic reagents (as selective as possible) are superior to stoichiometric reagents
• Chemical products should be designed so that at the end of their function they do not persist in the environment and breakdown into innocuous degradation products
• Analytical methodologies need to be further developed to allow for real-time inprocess monitoring and control prior to the formation of hazardous substances
• Substances and the form of substances used in a chemical process should bechosen so as to minimize the potential for chemical accidents, including releases, explosions and fires

A Series of Reductions
Risk &
Hazard
Cost
Reducing
Materials
Energy
Nonrenewables
Waste

How Efficient is Chemical Manufacturing?
E-factors
Industry Product tonnage Kg by-products /
Kg product
Oil refining 10 6 – 10 8 < 0.1
Bulk Chemicals 10 4 – 10 6 1 - 5
Fine chemicals 10 2 – 10 4 5 - 50+
Pharmaceuticals 10 - 10 3 25 - 100+

Industrial Ecology Goals for Green Chemistry
• Adopt a life-cycle perspective regarding chemical products and processes
• Realise that the activities of your suppliers and customers determine, in part, the greenness of your product
• For non-dissipative products, consider recyclability
• For dissipative products (e.g. pharmaceuticals, crop protection chemicals) consider the environmental impact of product delivery
• Perform green process design as well as green product design

Some Barriers to Adopting Greener Technology
·
Lack of global harmonisation on regulation / environmental policy
· Notification processes hinder new product & process development
· Lack of widely accepted measures of product or process “greenness”
· Lack of technically acceptable 'green' substitute products and processes
· Short term view by industry and investors
· Lack of sophisticated accounting practices focussed on individual processes
· Difficult to obtain R&D funding
· Difficult to obtain information on best practice
· Lack of clean, sustainable chemistry examples & topics taught in schools & universities
· Lack of communication / understanding between chemists & engineers
· Culture geared to looking at chemistry not the overall process / life cycle of materials

The Chemical Industry in the 21st Century
Meeting social, environmental and economic responsibilities
•
Maintaining a supply of innovative and viable chemical technology
•
Environmentally and socially responsible chemical manufacturing
• Teaching environmental awareness throughout the education process

Twilight creates illusion of light getting stronger.
Twilight then fades into a dark night.
It is always darkest before dawn.
If we solve our energy crisis, the 21st century will be our greatest dawn.
If we fail, we will have a dark future
.

• Having seen single molecules and their behaviour one has to turn the attention to aggregates.
• Why aggregates, it appears it is the natures way of preserving and fostering things – trees, plants, animals, human beings everything live as aggregates and care for the total aggregated assemblies and not for the individual species .

• The existence of single molecules can be understood from the point of view of minimization of free energy
• Aggregates how do they minimize the energy?
• What is the driving force for this aggregation?
• What is the type of interactions present in aggregation?

• What are weak bonding and how do they cause the aggregation?
• What are the energies involved in these weak forces?
• Are there a variety of these weak forces?
• Do they have any constraints in geometry, functionality, and electronic configuration?
• How these weak forces account for the stabilities observed

• Many bio-molecules are aggregates
• Materials are always aggregates but the dimensionality ( uni, bi and tri dimensions) impart unique properties Why?
• Not only dimensions but also size in nanoscale and bulk scale they are different – shows aggregation has a role to play even in terms of the number of species aggregating?

• This is a question one has to ask at this time
• It is known that the helical structure of vital species like DNA, collagen and other species? Why helical structure why not strings and wires and ropes?
• Twisted configurations why are they more stable than strings and wires?
• Nano coils and nano architectures how are they become more stable?

Some examples of aggregates in molecular systems

Directed Assembly addresses the fundamental scientific issues underlying the design and synthesis of new nanostructured materials, structures, assemblies, and devices with dramatically improved capabilities for many industrial and biomedical applications .
It focuses on discovering and developing the means to assemble nanoscale building blocks with unique properties into functional structures under well-controlled, intentionally directed conditions .
Directed assembly is the fundamental gateway to the eventual success of technology. It is based upon well-integrated research efforts that combine computational design with experimentation to discover novel pathways to assemble functional multiscale nanostructures with junctions and interfaces between structurally, dimensionally, and compositionally different building blocks. These efforts are leading to new methodologies for assembling novel functional materials and devices from nanoscale building blocks that will lead to novel applications of nanotechnology to spur industry into the 21st century.

Control of Polymer Supermolecular Morphology
A collaborative effort between L.S. Schadler, R.W. Siegel, Y. Akpalu (RPI) and ABB focuses on using nanoparticles to control the supermolecular morphology of semicrystalline polymers and their properties. The figure shows the effect of 20 nm diameter TiO2 nanoparticles dried or coated with
N-(2-aminoethyl)3-aminopropyl-trimethoxysilane (AEAPS) on low-density polyethylene (LDPE).
There is no change in unit cell dimension, degree of crystallinity, average lamellar thickness, or average spherulite size. The supermolecular structure, however, is impacted. Neat LDPE and the dried sample exhibit a well-defined, impinging, banded spherulite structure. The nanoparticles are embedded between the lamellae. In great contrast, no well-developed banded spherulites are observed in the AEPS sample, in which nanoparticles segregate to inter-spherulitic regions. This supermolecular structure is critical in controlling electrical breakdown strength in LDPE.
 m  m
 m
Figure: AFM tapping mode images of the supermolecular structures of (a) neat LDPE
(b) LDPE filled with more compatible dried TiO2 nanoparticles and (c), LDPE filled with non-compatible AEAPS coated TiO2 nanoparticles.

In the next few slides ( mostly reproduced from literature and none of them are our own) we demonstrate how aggregated systems are relevant, perform and exhibit unusual properties .
These are chosen randomly and no specific significance to be attached to the choice.

water molecule
Molecule of DNA
Water molecules – 3 atoms
Protein molecules – thousands of atoms
DNA molecules – millions of atoms
Nanowires, carbon nanotubes – millions of atoms
Protein molecule
Carbon nanotube

At least one dimension is between 1 - 100 nm
2-D structures (1-D confinement):
• Thin films
• Planar quantum wells
• Superlattices
1-D structures (2-D confinement):
• Nanowires
• Quantum wires
• Nanorods
• Nanotubes
0-D structures (3-D confinement):
• Nanoparticles
• Quantum dots
Multi-wall carbon nanotube
Dimensionality, confinement depends on structure:
• Bulk nanocrystalline films
• Nanocomposites
2
 m
Si Nanowire Array
Si
0.76
Ge
0.24
/ Si
0.84
Ge
0.16
superlattice http://www.aip.org/mgr/png/2003/186.htm

Nanoscale Thin Film
• Single “two dimensional” film, thickness < ~100 nm
• Electrons can be confined in one dimension; affects wavefunction, density of states
• Phonons can confined in one dimension; affects thermal transport
• Boundaries, interfaces affect transport a
Thin film
Bulk crystal
Substrate
Free standing thin film d http://scsx01.sc.ehu.es/waporcoj/charl as/cursodoctorado/12

• Solid, “one dimensional”
• Can be conducting, semiconducting, insulating
• Can be crystalline, low defects
• Can exhibit quantum confinement effects
(electron, phonon)
• Narrowing wire diameter results in increase in band gap
2
 m
• Narrowing wire diameter can result in decrease in thermal conductivity
Si Nanowire Array
• New forms include core-shell and superlattice nanowires
Nanotube defined – a long cylinder with inner and outer nm-sized diameters
Nanowire defined – a long, solid wire with nm diameter
Abramson et al, JMEMS (2003)
Wu et al, Nanoletters, Vol. 2, 83 – 86 (2002)
Si/SiGe Nanowires

Carbon nanotube properties:
• One dimensional sheets of hexagonal network of carbon rolled to form tubes
• Approximately 1 nm in diameter
• Can be microns long
• Essentially free of defects
• Ends can be “capped” with half a buckyball
• Varieties include single-wall and multi- wall nanotubes,ropes, bundles, arrays
• Structure (chirality, diameter) influences properties:
– Semiconducting vs. metallic
– Thermal, electrical conductance
– Mechanical strength, elasticity
Multi-wall carbon nanotube
Armchair
Zigzag http://physicsweb.org/article/world/11/1/9/1 http://www.aip.org/mgr/png/2003/186.htm
Chiral

Boron nitride nanotubes
• Resistance to oxidation, suited for high temperatures
• Young’s modulus of 1.22 TPa
• Semiconducting
• Predictable electronic properties independent of diameter and # of layers
Boron nitride nanotubes adopt various shapes
(red=boron, blue=nitrogen):
SiC nanotubes:
• Resistance to oxidation
• Suitable for harsh environments
SiC nanotubes grown at NASA
Glenn:
• Can functionalize surface Si atoms http://www.grc.nasa.gov/WWW/RT2002/5000/5510lienhard.html
http://pubs.acs.org/cen/topstory/7912/7912notw1.html

Cold
Metal organic framework for hydrogen storage
Hot
2
 m
I
Dresselhaus group, MIT
Replace conventional material with nanocomposite to enhance performance
Abramson et al , JMEMS , in review.
Rosi et al , Science , Vol. 300, pp. 1127
-1129 (2003).

Oil refinement: zeolites are nanoporous (pores 3 – 10 Å) crystalline solids with well-defined structures (“molecular sieves”) used in oil refinement – increases gasoline yield from each barrel of crude oil by 50% Porous zeolite structure http://www.iaee.org/docum ents/p03eagan.pdf
http://www.bza.org/zeolit es.html
2 atomic layer thick Au nanoclusters on TiO
2

Change the nanostructure of Si (a very cheap material) to become nanoporous and visible light is emitted!
Use quantum dots
(quantum confinement) for light emission
Cross-hairs of p-type and n-type nanowires (to get a p-n junction)
Network of nanowires http://www.trnmag.com/Stories/011701/Crossed_nano wires_make_Lilliputian_LEDs_011701.html
Quantum dot layers http://www.trnmag.com/Stories/2002/103002/Nanoscale_LED_debuts_103002.html

Quantum dots/ nanocrystals are smaller than the wavelength of light, so they do not scatter light; scattering can reduce optical efficiency by up to 50%!

Change electrode materials by nanostructuring (texturing) to improved electrical performance; nanoscale particles boost energy storage and power delivery by reducing the distance
Li ions travel during diffusion
Nanobattery: Fill a nanoscale membrane with an electrolyte, cap with electrodes; contact with a probe tip

Solar cells integrated into roof shingles
Nanoscale crystals of semiconductor coated with light-absorbing dye emit electrons
Nanostructured diamond solar thermal cells capture light, which heats the lattice, which emits electrons; small tip gives high energy electrons
Tetrapods (the light absorbing materials) double the efficiency of plastic solar cells because they always point in the right direction http://www.spacer.com/news/solarcell-01b.html
Nanostructured diamond solar thermal cells
Branched tetrapod

Dendritic Macromolecules as Unimolecular Micelles for
Organic Solutes
(Stribaet al. 2002, Angwate. Chemie. Int.
Ed., 41 (8), pp 1329-1324)
MD Simulations of the Meijer
Dendrimer Box Mikliset al. 1997,
JACS, 131, 7458

Catalytic DendriticMacromolecules
( AstrucD. and Chardac, F. Chem. Rev. 2001, 101, 2991-3023)

Dendrimer-Encapsulated Zero Valent Metal Clusters
( Scott et al. J. Phys. Chem. B. 2 005 , 109, 692-704 )

Bioactive Dendritic Macromolecules
(
Chen et al. 2000, Biomacromolecules, 1 (3): 473-480)

Fate, Transport and Toxicity of Dendritic aggregates
•
Numerous dendrimers their toxicity and bio-distribution studies have carried out during the last 5 years
• – The effects of dendrimer core and terminal group chemistry, size, shape, hydrophobicity on dendrimer interactions with cell membranes and toxicity are becoming known and understood.
• • Only a limited number of studies have been published on the fate and tranport of dendrimers in the environment
• –
Sorption of dendrimers onto mineral surfaces

Basic Research Needs to Assure a Secure Energy Future - Role of aggregates
 Materials Research to Transcend Energy Barriers
 Energy Biosciences
 Research Towards the Hydrogen Economy
 Energy Storage
 Novel Membrane Assemblies an example of aggregates
 Heterogeneous Catalysis- aggregate site density
 Energy Conversion-
 Energy Utilization Efficiency
 Nuclear Fuel Cycles and Actinide Chemistry
 Geosciences

• The concept of “ensemble effect” in catalysis is well known – this is a form of the aggregates that we call.
• The concept of “active site” is known in catalysis but these are not single atom site but some sites in particular locations with definite neighbours this is another version of aggregated sites.
• The concept of metal support interaction or as a matter of fact SMW interactions always imply an aggregated site – therefore the concept of aggregation and they behaving differently is known. SMSI and other interactions do not involve specific bonds and should be involving weak interactions .
• Weak interactions and its manifestations are therefore already known but has not been specifically indicated or identified .

Drivers for the Hydrogen Economy:
• Reduce Reliance on Fossil
Fuels
• Reduce Accumulation of
Greenhouse Gases
20
18
16
22
Energy Source
Oil
Natural Gas
Coal
Nuclear
Hydroelectric
Biomass
Other Renewables
% of U.S.
Electricity
% of Total
U.S. Energy
Supply
3
15
Supply
39
23
51
20
8
1
1
22
8
4
3
1
Actual Projected
14
12
10
8
6
Light Trucks
Rail
4
2
Cars
0
1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025
Year

The Hydrogen Economy
H
2
O solar wind hydro nuclear/solar thermochemical cycles
Bio- and bioinspired fossil fuel reforming
H
2 gas or hydride storage production
9M tons/yr
150 M tons/yr
(light cars and trucks in 2040) storage
4.4 MJ/L (Gas, 10,000 psi)
8.4 MJ/L (LH2)
9.70 MJ/L
(2015 FreedomCAR Target)
H
2 automotive fuel cells stationary electricity/heat generation consumer electronics use in fuel cells
$3000/kW
$30/kW
(Internal Combustion Engine)

Fundamental Issues
The hydrogen economy is a compelling vision:
- It potentially provides an abundant, clean, secure and flexible energy carrier
- Its elements have been demonstrated in the laboratory or in prototypes
However . . .
- It does not operate as an integrated network
- It is not yet competitive with the fossil fuel economy in cost, performance, or reliability
- The most optimistic estimates put the hydrogen economy decades away
Thus . . .
- An aggressive basic research program is needed, especially in gaining a fundamental understanding of the interaction between hydrogen and materials at the nanoscale

Hydrogen Production versus other fuel sources
Current status:
• Steam-reforming of oil and natural gas produces 9M tons H
2
• We will need 150M tons/yr for transportation
/yr
• Requires CO
2 sequestration.
Alternative sources and technologies:
Coal:
• Cheap, lower H
2 yield/C, more contaminants
• Research and Development needed for process development, gas separations, catalysis, impurity removal.
Solar:
• Widely distributed carbon-neutral; low energy density.
• Photovoltaic/electrolysis current standard – 15% efficient
• Requires 0.3% of land area to serve transportation.
Nuclear: Abundant; carbon-neutral; long development cycle.

Priority Research Areas in Hydrogen Production
Fossil Fuel Reforming Intermediate Term
Molecular level understanding of catalytic mechanisms, nanoscale catalyst design, high temperature gas separation
Solar Photoelectrochemistry/Photocatalysis
Light harvesting , charge transport, chemical assemblies, bandgap engineering, interfacial chemistry, catalysis and photocatalysis, organic semiconductors, theory and modeling, and stability
Ni surface-alloyed with Au to reduce carbon poisoning
Bio- and Bio-inspired H
2
Production
Microbes & component redox enzymes, nanostructured
2D & 3D hydrogen/oxygen catalysis, sensing, and energy transduction, engineer robust biological and biomimetic
Dye-Sensitized Solar Cells
H
2 production systems
Synthetic Catalysts for H
2
Production
Nuclear and Solar Thermal Hydrogen
Thermodynamic data and modeling for thermochemical cycle (TC), high temperature materials: membranes, TC heat exchanger materials, gas separation, improved catalysts
Thermochemical Water Splitting

Hydrogen Storage Panel
Current Technology for automotive applications
• Tanks for gaseous or liquid hydrogen storage.
• Progress demonstrated in solid state storage materials.
System Requirements
• Compact, light-weight, affordable storage.
• System requirements set for FreedomCAR: 4.5 wt% hydrogen for 2005,
9 wt% hydrogen in the near future.
• No current storage system or material meets all targets.
30
Energy Density of Fuels gasoline
20 liquid H
2
10 compressed gas H
2
0
0 complex hydrides proposed DOE goal chemical hydrides
10
20
30
Gravimetric Energy Density
MJ/kg system
40

• High gravimetric and volumetric density (9 wt %)
• Fast kinetics
• Favorable thermodynamics
• Reversible and recyclable
• Safe, material integrity
• Cost effective
• Minimal lattice expansion
• Absence of embrittlement

Fuel Cells and Novel Fuel Cell Materials Panel
2H
2
+ O
2


2H
2
O + electrical power + heat
2H
Current status:
Limits to performance are materials, which have not changed much in 15 years.
Challenges:
Membranes
Operation in lower humidity, more strength, durability and higher ionic conductivity.
Cathodes (PEM)
Materials with lower overpotential and resistance to impurities.
Low temperature operation needs cheaper (non- Pt) materials.
Tolerance to impurities: S, hydrocarbons, Cl.
Anodes
Tolerance to impurities: CO, S, Cl.
Cheaper (non or low Pt) catalysts.
Reformers
Need low temperature and inexpensive reformer catalysts.

Fuel Cell Model
THE ISSUE : better, cheaper, more durable, impurity tolerant materials.
Most must/will be structured on the nanoscale.
External Load NOT TO SCALE
Fuel:
H
2
, CH
4
, CH
3
OH
Chemical Oxidation:
Liberates e e ’s
Oxygen (O
2
)
Chemical Reduction:
Consumes e -
Ion
Transp.
Reaction
Products
Reaction
Products
Anode
(Oxidation)
Frank DiSalvo (Cornell)
Ionic Conductor
(Membrane)
Cathode
(Reduction)

Very challenging . Electrodes need to support three percolation networks: electronic, ionic, fuel/oxidizer/product access/egress.
2 –5 nm
20 -50
 m

Alloy; e.g. Pt/Ru (1:1)
Ordered Intermetallic e.g. BiPt
(A) (B)
“Electrocatalytic Oxidation of Formic Acid at an Ordered Intermetallic PtBi Surface”, E.
Casado-Rivera, Z. Gál, A.C.D. Angelo, C. Lind, F.J. DiSalvo, and H.D. Abruña, Chem.
Phys. Chem. 4, 193-199 (2003)

Enhanced Catalytic Activity for Formic Acid Oxidation
 Cyclic Voltammetry in 0.1 M H
2
SO solution at a sweep rate of 10 mV/s
4
+ 0.125 M formic acid
Pt
0.063 mA/cm 2
PtBi
2.4 mA/cm 2
8
-0.2
0.0
0.2
0.4
0.6
0.8
-0.2
0.0
0.2
0.4
0.6
0.8
1.0

Basic Research Needs for the Hydrogen Economy
 Nanoscale Materials and Nanostructured Assemblies
 Catalysis
- hydrocarbon reforming
- hydrogen storage kinetics
- fuel cell and electrolysis electrochemistry
 Membranes and Separation
 Characterization and Measurement Techniques
 Theory, Modeling and Simulations
 Safety and Environment

Hydrogen Studies universal finding: the hydrogen economy requires breakthrough basic research to find new materials and processes
 define a new state of the art

Directed Assembly addresses the fundamental scientific issues underlying the design and synthesis of new nanostructured materials, structures, assemblies, and devices with dramatically improved capabilities for many industrial and biomedical applications.
It focuses on discovering and developing the means to assemble nanoscale building blocks with unique properties into functional structures under wellcontrolled, intentionally directed conditions.
Directed assembly is the fundamental gateway to the eventual success of nanotechnology. It is based upon well-integrated research efforts that combine computational design with experimentation to discover novel pathways to assemble functional multiscale nanostructures with junctions and interfaces between structurally, dimensionally, and compositionally different building blocks. These efforts are leading to new methodologies for assembling novel functional materials and devices from nanoscale building blocks that will lead to novel applications of nanotechnology to spur industry into the 21st century.

Nanoparticle Control of Polymer Supermolecular
Morphology
A collaborative effort between L.S. Schadler, R.W. Siegel, Y. Akpalu (RPI) and ABB focuses on using nanoparticles to control the supermolecular morphology of semicrystalline polymers and their properties. The figure shows the effect of 20 nm diameter TiO2 nanoparticles dried or coated with
N-(2-aminoethyl)3-aminopropyl-trimethoxysilane (AEAPS) on low-density polyethylene (LDPE).
There is no change in unit cell dimension, degree of crystallinity, average lamellar thickness, or average spherulite size. The supermolecular structure, however, is impacted. Neat LDPE and the dried sample exhibit a well-defined, impinging, banded spherulite structure. The nanoparticles are embedded between the lamellae. In great contrast, no well-developed banded spherulites are observed in the AEPS sample, in which nanoparticles segregate to inter-spherulitic regions. This supermolecular structure is critical in controlling electrical breakdown strength in LDPE.
 m  m
 m
Figure: AFM tapping mode images of the supermolecular structures of (a) neat LDPE
(b) LDPE filled with more compatible dried TiO2 nanoparticles and (c), LDPE filled with non-compatible AEAPS coated TiO2 nanoparticles.