Michael W. Tausch

Havana

VaraderoJune, 2015

Photoprocessesin Chemical Education

Scientific Talk: Towards Photocatalytic CO2 Reduction

University Chemistry

of Wuppertal Education

Program

Curriculum Innovation

I: Why photoprocesses?

II: Didactical Credo

III: Experiments & Concepts

Outline:

Innovative Contents ► Experiments ► Teaching Concepts ► Printed and Eletronic Media

Photoprocesses in

Science Education

„It is now clear that electronically excited states of molecules

are the heart of all photoprocesses.The excited state is in fact

an electronic isomer of the ground state.“N. J. Turro, Modern Molecular Photochemistry. Benjamin/Cummings, N.Y. (1978)

Chemical education … deals with the metamorphosis of how to teach chemistry

„A pretty Experiment quite often is more precious than twenty

equations bred in the thinking retort.“A. Einstein, 1955

„Chemistry … deals with the metamorphosis of matter“A. F. Kekulé, 1855

E = mc2

Photoprozesse in der Lehre

der Naturwissenschaften

Light

S1→S0T1→S0

Luminescence: F, P, CL, EL, ECL

Energy transfer

Elektron transferFurther reaction

types

Isomerization

Photovoltaics

Photoprocesses in

Science Education

Requirements for a „pretty“ Experiment: ►appealing & beautiful ► instant & inexpansive

►secure & clean ► innovative & grean ► …

►didactically concise & scientifically consistent

Photoprocesses in

Science Education

Paradigm: Atomic and molecular systems can exist in the electronic ground state

as well as (even for a short time) in electronically excited states.

M.Tausch, M. v. Wachtendonk , C. Bohrmann-Linde, S. Krees (Hrsg.), CHEMIE 2000+, C.C.Buchner, Bamberg (2007…2014)

The energy level model for molecules – A core concept in chemistry

excited state T1

τ = 10-2 – 102 s

excited state S1

τ = 10-9 – 10-8 s

Fluorescence

Phosphorescence

Exchange

of heat

lowest

unoccupied

energy level

highest

occupied

energy level

ground state So

M.T., D. Paterkiewicz, PdN-Chemie 36, 14 (1988); M.T., A. Grolmuss, M. Woock, PdN-Physik 47, 10 (1998); M.T., F.Gärtner, PdN-ChiS, 53, 20 (2004)

Photoprocesses in

Science Education

www.chemiedidaktik.uni-wuppertal.de > Vorträge; oder > Teaching Photochemistry

Photoprocesses in

Science Education

Melting 5 g

of tartric acid

Adding 5 mg

of Aesculene

Mixing and distributing

the melted mass

Testing the photo-

luminescence

Fluorescence at

room temperaturePhosphorescence at

room temperature

Video

Leuchtendes Scherblatt

Leuchtende Elektroden

with C. Bohrmann, ChiuZ 36 (3), 164 (2002) ; with J. Ibanez, C. Bohrmann -Linde u.a. J. Chem. Educ.. , 90 (4), 470 (2013)

(KOH + DMSO + Luminol)

www.chemiedidaktik.uni-wuppertal.de

Generation of the excited state

Chemical

reaction

Ground

state

Excided

state

Photoprocesses in

Science Education

The Glowing Razor Foil

Self made-OLED‘s

• Basic-OLED

• Flexi-OLED

• Easy-OLED

• Quick-OLED

Photoprocesses in

Science Education

with A. Banerji, U. Scherf, M. T., Chemkon, 19 (1), 7 (2012); with A. Banerji, U. Scherf , M. T. , Educ. Quimica , 24 (1), 17 (2013)

with C. Bohrmann, ChiuZ 36 (3), 164 (2002) ; with J. Ibanez, C. Bohrmann -Linde u.a. J. Chem. Educ.. , 90 (4), 470 (2013)

www.chemiedidaktik.uni-wuppertal.de

Chemoluminescence

Color by absorp-

tion of light

LB

VB e-

LB

VB

angeregter Zustand

e-

e-

e-

e-

h

Grundzustand

Pluspol

Minuspol

E

Electroluminescence

Chemical Core Concept

Ground State

and

Electronically Excited

States

Photoprozesse in der Lehre

der Naturwissenschaften

Photoluminescence

Fluorescence

Photoprocesses in

Science Education

Phosphorescence

non radiative

deactivation

DIN A5 ca. 4 €

E.D.Bergmann, A.Weizmann, E.Fischer, JACS, 72, 5009 (1950), M. T., Chemkon, 3, 123 (1996)

S. Krees, PdN-ChiS, 62 (8), 35 (2013); M. T., PdN-ChiS, 64 (1) 5 (2015)

Polystyrol

Toluol

PET-Folie

Light

Heat

Spiropyrane C19H18O3N2 Merocyanine C19H18O3N2

10

Non Polar

Nano-Enviroment

(Polystyrene)

Polar

Nano-Environment

(Nitrocellulose)

Mero SpiroSpiro Mero1 Basic Experiment

2 Wavelength

3 Temperature

4 Thin Layer

5 Matrix / Solvent

Photoprocesses in

Science Education

Chemie 2000+ , C.C. Buchner, Bamberg (2002..2014)

S. Spinnen, M. Essers, S. Krees, M. T., PdN-ChiS, 63, (2) 35 (2014);

S. Spinnen, M. T. PdN-ChiS 64 … (2015)

Photoprocesses in

Science Education

Beng Zhing Tang et al. „Aggregation-Induced Emission:

The Whole Is More Brilliant than the Parts“, Adv. Mat. DOI 10.1002 (2014)

S. Spinnen, M. Essers, S. Krees, M. T., PdN-ChiS, 63, (2) 35 (2014);

S. Spinnen, M. T. PdN-ChiS 64 … (2015)

Photoprocesses in

Science Education

S. Spinnen, M. T. PdN-ChiS 64 in press (2015)

Stokes Shift: 120 nm

Stokes Shift: 120 nm

Photoprocesses in

Science Education

Angeregter

Zustand

Grundzustand

Thermische Reaktion vs. photochemische Reaktion

M. W.Tausch, Chemkon, 3, 123 (1996)

Thermischer

Reaktionsweg

Photochemischer

Reaktionsweg

M.Tausch, M.v.Wachtendonk (Hrsg.), CHEMIE 2000+, C.C.Buchner, Bamberg (2007…2010)

E.D.Bergmann, A.Weizmann, E.Fischer, JACS, 72, 5009 (1950)

Photochemical

Reaction

Pathway

Thermal

Reaction

Pathway

Reaction Coordinate

Photosteady

State

Photoprocesses in

Science Education

S. Shinkai et al. Bull. Chem. Soc. Jap., 60, 1819, (1987)

V. Ramamurthy, Photochemistry in Organized and Constrained Media, VCH, (1991)

D. Wöhrle, M.W. Tausch, W.-D. Stohrer, Photochemie, Wiley-VCH, (1998)

… a Molecular

Trojan Horse

… a Molecular „Vise“

(„Screw Matrix“)

Photoprocesses in

Science Education

M. Tausch, M.von Wachtendonk, C. Bohrmann-Linde, S. Krees (Hrsg.) Chemie 2000+ , C.C. Buchner, Bamberg (2002..2014)

K. Palczewski et al. „Crystal Structure of Rhodopsin...“. SCIENCE 289, 739 (2000)

M. T, M. Woock, A. Grolmuss: „Vom Lichtquant zum Sehreiz“, PdN (Physik), 47, 26 (1998)

… the photoswitch

in eye rhodopsine3 Millions of Retinal Cones

+ 100 Millions of Retinal Rods

Photoprocesses in

Science Education

„Viviamo sul fondo

di un oceano d‘aria“Evanghelista Torricelli, 1640

Satellite Photograph: Narrows of Gibraltar, 1995

Photoprocesses in

Science Education

poco despues de

la creation del Universo ...

Y dios dijo:

„Hagase la luz.“

Y la luz fue hechaBiblia, 1. Mose, Vers 4

…un requisito indispensable

para la vida en la tierra.

Y dios vio que

la luz era buena.Biblia, 1. Mose, Vers 4

Photosynthesis in numbers700.000.000.000 t Biomass/a 3.000.000.000.000.000.000.000 J/a 0,15%

Photoprocesses in

Science Education

yellow

solution

blue

solution

+hνλ < 450 nm

+O2

Silke Korn

Silke Korn

Shake

1. a light driven reduction

2. an oxygen consuming oxidation

3. the need of a light absorbing species

the natural cycle of

photosynthesis and respiration

M. T. , D. Wöhrle „“Photokatalyse“ PdN-Chemie 38 (3), 37 (1989); M.T. „Photo-Blue-Bottle …“ . PdN-Chemie 43 (3), 13 (1994)

S .Korn, M. T., J. Chem. Educ. 78 (9), 1238 (2001); … M. Heffen, M. T., PdN-ChiS, 64 (2), 45 (2015)

D. Wöhrle. M.Tausch, W.-D. Stohrer, Photochemie – Konzepte, Methoden, Experimente, Wiley-VCH, Weinheim (1998)

Photoprocesses in

Science Education

Photoprocesses in

Science Education

c ≈ 5.10-5 mol/l

c ≈5. 10-3 mol/l

excessM. T., S .Korn, J. Chem. Educ. 78 (9), 1238 (2001); M. T., M. Heffen, R. Krämer, N. Meuter, PdN-ChiS, 64 (2), 45 (2015)

Sacrificial

DonorPhotocatalyst Substrate

Oxidizing

Agent

c = 5.10-3 mol/Lc = 5.10-5 mol/LExcess

Supply

Light

Model-Sugar

Model-CO2

Photoprocesses

in Science Education

M. W. Tausch, PdN-ChiS 43 (3), 13 (1994)

EV2+

EV+

EthylviologeneProflavine

or TiO2

E

Electronically excited state

Highest occupied

energy level (HOMO)

Lowest unoccupied

energy level (LUMO)

AA

A

Endergonic

Reduction

Photoprocesses in

Science Education

Photosynthesis

Apparatus

C- and O-

cycles

Respiratory

Apparatus

Light

Mechanical, thermic

and other Energies

Energy

Photoprocesses

in Science Education

M. Tausch, M.von Wachtendonk, C. Bohrmann-Linde, S. Krees (Hrsg.) Chemie 2000+ , C.C. Buchner, Bamberg (2002..2014)

Shake

Light

Model-Sugar

Model-CO2

Energy

EV++

EV+Energy

Ethylviologene

EV2+ + e- EV+

C. Bohrmann-Linde, F. Posala, D. Nietz, M. T., PdN-ChiS 62 (5), 25 (2013)S .Korn, M. T., J. Chem. Educ. 78 (9), 1238 (2001);

M. Heffen, M. T. PdN-ChiS; in press

- +

X Light on

X Light off

● Air on

Air off

Time [min]

Vo

lta

ge

[mV

]

Conclusion:Light is converted

into chemical energy and

stored in the reduced substrate.

Photoprocesses

in Science Education

1LED

400 nm

3LED

530 nm

4LED

630 nm

100 nm

Nano-TiO2

REM

M.T., D. Wöhrle: PdN (Chemie) 38, 37 (1998); …M.T.., M. Heffen, PdN-ChiS 64 in press (2015)

M.Tausch, M. v. Wachtendonk , C. Bohrmann-Linde, S. Krees (Hrsg.), CHEMIE 2000+, C.C.Buchner, Bamberg (2007…2014))

Photoprocesses in

Science Education

1LED

400 nm

3LED

530 nm

4LED

630 nm

Photoprocesses in

Science Education

388 nm

(3,1 eV)

Eg = 3,1 eV

EV++

EV+

TEA

TEAox

TiO2-Particle

Conduction Band

Valence Band

M.T., D. Wöhrle: PdN (Chemie) 38, 37 (1998); …M.T.., M. Heffen, PdN-ChiS 64 in press (2015)

M.Tausch, M. v. Wachtendonk , C. Bohrmann-Linde, S. Krees (Hrsg.), CHEMIE 2000+, C.C.Buchner, Bamberg (2007…2014))

Photosynthesis-

apparatus

C- and O-

Cycles

Respiratory-

apparatus

Light

Mechanical, Thermic

and other Energies

Energye

Light

Modll-Shugar

Model-CO2

Energy

M. T., M. Heffen, PdN-ChiS; eingereicht, M. Tausch, M.von Wachtendonk, C. Bohrmann-Linde, S. Krees (Hrsg.) Chemie 2000+ … (2002..2014)

Ein starkes Paar

EV++

EV+

h∙ν

+O2

Ethylviologene

TiO2

TiO2 *

TiO2+

TEA

TEAox

Photoprocesses in

Science Education

Shake

Light

Model-H3COH … Energy

EV++

EV+

Model-CO2

Ethylviologene

Green

Fuel

K. K. Sakimoto, P. Yang, D. Kim, Angew. Chem. 127, 3309 (2015)

Photoprocesses in

Science Education

Connected MediaOnline-Supplements for Textbooks:

Model Animations, Videos,

Interactive Worksheets etc.

Chemistry & Chem. Educ.

Michael W. Tausch

Dr. Claudia Bohrmann-

Linde

Prof. Dr. Simone Krees

Dr. Amitabh Banerji

Dr. Ralf-Peter Schmitz

Dr. Bernd Rohe

Rebecca Roggendorf

Heidrun Geller

René Krämer

Nico Meuter

Maria Heffen

Melanie Zepp

Heiko Hoffmann

Sebastian Spinnen

Ibeth Rendón Enríquez

Ingrid Reisewitz-Swertz

Renate Gärtig

David Nietz

Frederic Posalla

Saskia Ruckebier

u.v.a.