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Advanced Course in Environmental Catalytic Reaction Chemistry I 1

2020/08/13

環境触媒化学特論I

15


Advanced Course in Environmental Catalytic Chemistry I

understanding chemistry by understanding photocatalysisunderstanding photocatalysis by understanding chemistry

Division of Environmental Material Science, Graduate School of Environmental ScienceThe first semester of Fiscal 202008:45─10:15, Thursday on Zoom

Bunsho Ohtani

Institute for Catalysis, Hokkaido University, Sapporo 001-0021, Japan011-706-9132 (dial-in)/011-706-9133 (facsimile)

[email protected]://pcat.cat.hokudai.ac.jp/pcat

https://pcat.cat.hokudai.ac.jp/cgi-bin/class/db_class_e.cgi?mode=display_pc2020


schedule

(1) May 7 introduction of photocatalysis(2) May 14 interaction between substances and light(3) May 21 electronic structure and photoabsorption(4) May 28 thermodynamics: electron and positive hole(5) June 4 adsorption(6) June 11 kinetic analysis of photocatalysis(7) June 18 steady-state approximation(8) June 25 kinetics and photocatalytic activity(9) July 2 action spectrum analysis (1)(10) July 9 action spectrum analysis (2)(11) July 16 light intensity-dependence analysis(12) July 23 crystal structure (1)(13) July 30 crystal structure (2)(14) August 6 design and development of photocatalysts (1)(15) August 13 design and development of photocatalysts (2)


format

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special report (20 + α points)

special report for extra (bonus) score (20 point)report on critical review on "photocatalysis" in Wikipedia, pointing out errors, misunderstanding and speculationsbased on the contents of this lecture.http://en.wikipedia.org/wiki/Photocatalysishttp://ja.wikipedia.org/wiki/光触媒

• Japanese or English• A4 size 2 pages• submission by email attachment• a PDF file is more preferable than a Word file• email title: pc20200820-XXXXXXXX• file name: pc20200820-XXXXXXXX.pdf (or .docx or .doc)• deadline of submission: August 20, 2020 23:59

7

Fujishima, A.; Honda, K., Nature 238, 37 (1972).

19,910 citationsat July 3, 2020

8B. Ohtani, "Photocatalysis A--Z: What We Know and What We Don't Know", J. Photochem. Photobiol. C: Photochem. Rev., 11 (2010) 157-178.

band-structure model (BSM)

9

band structure (for an infinite-sized crystal)

CB

VB

surfacesurface

band-structure modelbulk only = no surface/size properties

10

homogeneous and heterogeneous photocatalysis

e

e

molecule/metal complex particle

LUMO

HOMO

CB bottom

VB toph

e

2H2O

O2 + 4H+

+1.23 V

4h+

band-structure modelno multielectron-transfer concept

11

ETDOSMETSEP

density-of-states (DOS)distribution

standard electrode potential

multielectron transfer = number of electrons

identification with electron-trap distribution

12

ETDOSMETSEP





RDB-PAS reversed double-beam photoacoustic spectroscopy

enables measurements of

ERDT/CBB patternsenergy-resolved distribution of electron traps/conduction-band bottom

of semiconductor (metal oxide) solids for

• identification (as a novel concept)

• detailed characterization

electron trap

macro- micro-scopic scopic

surface

bulk

XRD

TEM

STM AFM

SSA(specific surface area)

XPS

UPS

EDX

Raman

IRED

(electron diffraction)solid NMR

LEED

XRF

RDB-PAS

15

minimum requisits for

identification bulk structure bulk/surface size surface structure

ener

gy fr

om v

alen

ce-b

and

(VB)

top/

eV

3.4

3.2

3.0

2.8

2.6

2.4

2.2

2.0

20100

<97>

CB

ET density/µmol g-130

CBBbulk structure

conduction-band bottom

TDbulk (surface) size

total ET density

energy-resolveddensity of ETs

ERDTsurface structure

16

ERDT: energy-resolved distribution of traps

ET density/μmol g-1

anatase anatase rutile rutileonly > rutile > anatase only

ET density/μmol g-1 ET density/μmol g-1ET density/μmol g-1

fingerprint of titaniaslike NMR patterns for organic molecules

17

replotting of data withseven-point non-weightedmoving average

● CH3OH → HCHO + H2● CH3COOH + 2O2 → 2CO2 + 2H2O● 4Ag+ + 2H2O → 4Ag + O2 + 4H+

degree of coincidence

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

ζ pc

ζ

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

ζpc

ζ

identification of

powders (semiconducting materials with band gap and ETs)

bulk composition CBB bulk size (surface size) total ET density surface structure ERDT pattern

XRD patternnitrogen ads. (BET)-----

物質の同定

identificationpurity

純度

20

octahedral anatase particles (OAP)• naturally occurring (but

contaminated)• 8 equivalent {101} facets• possible morphology dependent

photocatalytic activity

(101)

O

Ti

Amano, F.; Yasumoto, T.; Prieto-Mahaney, O.-O.; Uchida, S.; Shibayama, T.; Ohtani, B. Chem. Commun. 2009, 2311-2313.

21

bulk (crystal) surfacesize

homogeneoussize distribution

pure!

100% crystalline(anatase)

pure!

100% {101}(octahedral)

pure!

純物質/標準物質

pure/authentic sample

22

%anatase 94 97 99 99

%OAP 76 96 92 96

ssa/m2 g-1 31 21 17 15

dET/μmol g-1 31 21 18 18

size/nm 121 183 228 291

Yumin LI

hydrothermally synthesizedoctahedral anatase (A) particles (OAPs)

23

0%

20%

40%

60%

80%

100%Pe

rcen

tage

of

num

ber o

f par

ticle

s w

ithin

a ra

nge

±5%

±10%

±15%±20% ±30%

ca. 80% in ±20% size

%anatase 94 97 99 99

%OAP 76 96 92 96

ssa/m2 g-1 31 21 17 15

dET/μmol g-1 31 21 18 18

size/nm 121 183 228 291

24

total ET density and specific surface area

y=0.87x+3.56R2=0.958

0 5 10 15 20 25 30 350

5

10

15

20

25

30

35To

tal d

ensi

ty o

f ETs

/ μm

ol g

-1

Specific surface area / m2g-1specific surface area/m2 g-1

tota

l ET

dens

ity/μ

mol

g-1

slope (0.87) =

ca. 0.5 ETs/nm2ca. 0.5 ET nm‒2

25

ERDT-pattern purity

normalized at peak tops

similar narrower width for OAPs

wider width for commercial sample

single Gaussian fits

26

5-coordinated Ti6-coordinated Ti4-coordinated Ti

Shirai, K.; Fagio, G.; Sugimoto, T.; Selli, D.; Farraro, L.; Watanabe, K.; Haruta, M.; Ohtani, B.; Kurata, H.; Di Valentin, C.; Matsumoto, Y. J. Am. Chem. Soc. 2018, 140, 1415-1422.

certain site ofca. 0.5 nm‒2

density

27

bulk (crystal) surfacesize

homogeneoussize distribution

pure!

100% crystalline(anatase)

pure!

100% {101}(octahedral)

pure!freedom = variable

28

0 50 100 150 200 250 3000

100

200

300

400R

elat

ive

activ

ities

(FP6

) (%

)

Average length of OAP / nm

O2 (Ag+)CO2

H2

average height of OAP/nm

rela

tive

activ

ity to

FP6

(%)

CH3COOH + 2O2

→ 2CO2 + 2H2O

CH3OH → HCHO + H2

4Ag+ + 2H2O → 4Ag + O2 + 4H+

particle size-dependent activitytrue

29

ETDOSMETSEP





30

♪

modulated light continuous light

methanol saturatedargon gas atmosphere

625 nm80 Hz

scanning

CB

VB

direct excitation

filling electron traps selectively from deeper side

reversed double-beam photoacoustic spectroscopy (RDB-PAS)

31

ca. 0.1-0.2 eV shiftenergy difference between VBT and high DOS part

RDB-PAS

photochemical method

32

absorption-edge wavelength• absorption edge: corresponding to band gap• apparently the edge is not SHARP due to distribution of "density of

states"

DOSdensity of states

negligible DOS at the edges = less photoabsorption

h-DOS

33

brookite

BCB

20100

<69>NTB-1

brookite

0 10 20 30

<192>Wakoamor-phous

CB

anatase

A A +R R +A

rutile

R

amorphouscommercial titania powders

ET density/µmol g-1

ener

gy fr

om V

B to

p/eV

ener

gy fr

om h

-DO

S(VB

)/eV

34

ERDT patterns of anatase-rutile mixture

35

orbital overlapping

h-DOS

h-DOS

ET of anatase

VB of rutileh-DOS

energy difference in VB-ET excitation

ET of rutile

VB of anatase

ICTEinterfacial charge-transfer excitation through spaciallyoverlapped orbitals of contacted particles

36

ETDOSMETSEP





37

so-called "band-structure" model of photocatalysis

CB

VBh

e

h+

e－

size?

38

2H2O O24e－

－4e－

photocatalytic solar hydrogen production/carbon dioxide fixation

photocatalytic organics decomposition

thermodynamically favorable: ΔG < 0

thermodynamically unfavorable: ΔG > 0

39

water-oxygen reactions in heterogeneous photocatalysis

oxygen reduction

CB

VBh

e

O2－

O2

-0.28 V

e－

water oxidation

CB

VBh

e

2H2O

O2 + 4H+

+1.23 V

4h+

40

Dr. Shugo TAKEUCHI Photocatalysis 1 Young Poster Award, First International Symposium on Recent Progress of Energy and Environmental Photocatalysis held in Tokyo University of Science (2015/09/03-04)

Faraday Division Poster Award, Faraday Discussion: Artificial Photosynthesis, Kyoto (2017/02/28-03/03)

41

0

2000

4000

6000

-0.5

-0.4

5-0

.4-0

.35

-0.3

-0.2

5-0

.2-0

.15

-0.1

-0.0

50.

05 0.1

0.15 0.

20.

25 0.3

0.35 0.

40.

45 0.5

distance from the center/cm

inte

nsity

/mW

cm

-2

effective irradiationarea: 0.12 cm2

0

500

1000

1500-0

.5-0

.45

-0.4

-0.3

5-0

.3-0

.25

-0.2

-0.1

5-0

.1-0

.05

0.05 0.

10.

15 0.2

0.25 0.

30.

35 0.4

0.45 0.

5

distance from the center/cm

inte

nsity

/mW

cm

-2

effective irradiationarea: 0.64 cm2

calibrated light intensity (IL)= 0.95×312 mW/0.12 cm2 = 2470 mW cm-2

calibrated light intensity (IL)= 0.95×330 mW/0.64 cm2 = 490 mW cm-2

highly intense UV-LEDs

◯ HMP-type (unfocused)

● NSL-type (focused)

IMAX: ~340 mW/cm2

IMAX: ~500 mW/cm2

42

anatase 4 nm IO3-NSL/HMP UV-LED

43

TiO2

TiO2(h+)

h+ e- IO3-/Fe3+

1/τ1

ILψφIL ψ2 φ

TiO2(2h+)

h+h+

k

H2O2

O2

1/τ2

44

TiO2

TiO2(h+)

h+ e- IO3-/Fe3+

1/τ1

I LψφI Lψ2φ

TiO2(2h+)

h+h+

k

H2O2

O2

1/τ2

r = I L2ψψ2φ2 / ( (1/τ1) + I L ψ2φ )

at low I L

at high I L

r = IL2ψψ2φ2τ1

r = ILψφ

I thr = 1 /ψ2φτ1

45

small (×1) large (×2)ψ (S) = ψ (L)

positive hole created by first-step photon

ψ2 (S) << ψ2(L)

positive hole created by second-step photon

47

TiO2

TiO2(h+)

h+ e- IO3-/Fe3+

1/τ1

I LψφI Lψ2φ

TiO2(2h+)

h+h+

k

H2O2

O2

1/τ2

I thr = 1 /ψ2φτ1

τ1

ψ2

φ

48

n = 1

n = 2 (slope)ψφ1/ ψ2φτ1 = Ithr

light intensity

reac

tion

rate

two-photon absorption

guaranteed

h+h+

h+

h+h+h+h+

r = I L2ψψ2φ2 / ( (1/τ1) + I L ψ2φ )

at low I L

at high I L

r = I L2ψψ2φ2τ1

r = I Lψφ

I thr = 1 /ψ2φτ1

49

O2 + e－＝ O2－ 1 －0.56 V

O2 + e－ + H+＝ HO2 1 －0.13 V

O2 + 2e－ + 2H+＝ H2O2 2 0.68 V

O2 + 4e－ + 4H+＝ 2H2O 4 1.23 V

HO2 + e－ + H+ ＝ H2O2 1 1.5 V

H2O2 + 2e－ + 2H+＝ 2H2O 2 1.77 V

HO・+ e－ + H+ ＝ H2O 1 2.8 V

50

anatase 4 nm IO3-NSL/HMP UV-LED

51

IO3-

small anatase (4 nm) large anatase (170 nm)

small rutile (13 nm) large rutile (360 nm)

NSL/HMP UV-LED

52

small anatase (4 nm) large anatase (170 nm)

small rutile (13 nm) large rutile (360 nm)

IO3-NSL/HMP UV-LED

LID: light intensity dependence

53

O2 + e－＝ O2－ 1 －0.56 V

O2 + e－ + H+＝ HO2 1 －0.13 V

O2 + 2e－ + 2H+＝ H2O2 2 0.68 V

O2 + 4e－ + 4H+＝ 2H2O 4 1.23 V

HO2 + e－ + H+ ＝ H2O2 1 1.5 V

H2O2 + 2e－ + 2H+＝ 2H2O 2 1.77 V

HO・+ e－ + H+ ＝ H2O 1 2.8 V

54

r = I 2ψ2ψφ2 / ( (1/τ) + I ψ2φ )

at low I

at high I

r = I 2ψ2ψφ2τr = I φψ

I thr = 1 /φψ2τ

effect of oxygen-evolutionco-catalysts

55

-4 -3 -2 -1 0 1 2

ln(IL/W cm-2)

3

2

1

-2

0

-1

ln(r/

μmol

h-1

cm-2

)

1

2

Bare MT150AMnO2-mix0.1 wt%MnO20.5 wt% MnO2

Bare MT150AMnO2-mix0.1 wt% MnO20.5 wt% MnO2

r = I2ψ2ψφ2 / ( (1/τ) + I ψ2φ )

at low I

at high I

r = I2ψ2ψφ2τ

r = I φψ

I thr = 1 /φψ2τ

56

-5 -3 -2 -1 0 1 2

ln(IL/W cm-2)

4

2

-2

0ln(r/

μmol

h-1

cm-2

)

1

2

Bare

MnO2

CoPi

IrO2

-4

0.1 wt% loading

r = I2ψ2ψφ2 / ( (1/τ) + I ψ2φ )

at low I

at high I

r = I2ψ2ψφ2τ

r = I φψ

I thr = 1 /φψ2τ

57

-4 -3 -2 -1 0 1 2

ln(IL/W cm-2)

5

2

-2

0

ln(r/

μmol

h-1

cm-2

)

1

2Bare

MnO2

IrO2

-1

1

3

4

14

58

large rutile

59

h+

h+

h+

EV

h+

h+h+

h+

EV

EV EV

EV EVEV

EV

EV

h+

h+

EV

EV

h+

h+

h+

h+h+

h+

EVEVEV

EVEV

loading0

loading1

loading5

volume×8

volume×8

EV governs ψ2

effective volume (EV)

60

Professor Mai TAKASE

(Graduate School of Engineering, Muroran

Institute of

Ms. Haruna HORI(Ph. D.

Candidate, Graduate School of Environmental

Science, Hokkaido

Awarded "The 12th Honda-Fujishima

Prize" (March 2016)

Awarded "The Best Presentation

Award" in 2015 Summer Meeting

of Chemical Society (July

2015)

Professor Mai TAKASHIMA

(Institute for Catalysis, Hokkaido

Ms. Chiharu YAMADA

(Master course, Graduate School of

Environmental Science, Hokkaido

Awarded "The Best Presentation Award"

in 2019 Winter Meeting of

Chemistgry-related Societies (January

2019)

61

BWO: bismuth tungstate (Bi2WO6) photocatalyst

433 K

403 K

463 K

photoirradiation （> 400 nm）

493 K

CO2

CO

2ev

olut

ion/

μmol

60

50

40

30

20

10

00 2 4 6 8 10

12time /h

CH3CHO + 5/2 O2 → 2CO2 + 2H2O

F. Amano, K. Nogami, B. Ohtani,Langmuir 2010, 26, 7174.

1 μm

300 nm

F. Amano, K. Nogami, R. Abe and B.Ohtani, Chem. Lett. 2007, 36, 1314.

63

intensity dependence

Merck (anatase) titania

dehydrogenation of methanol<platinum-loaded/under argon>

first-order = linear

mineralization of acetic acid<under air>

0.5th = square root

at higher intensity

0th = constant rate, due to diffusion (of O2?)-limited process

light intensity/mW cm-2

appa

rent

qua

ntum

effi

cien

cy (Φ

app)

1

0.1

0.01

1

0.1

0.01

0.1 101

CH3COOH + 2O2

→ 2CO2 + 2H2O

CH3OH → HCHO + H2

290 nm

350 nm

380 nm

395 nm

64

radical chain mechanism

peroxy radical as a chain carrierI : incident photon flux; f : photoabsorption efficiency; j : intrinsic quantum efficiency

stationary (steady) state approximation for RO2· and R·

RH → R·R· + O2 → RO2·RO2· + RH → RO2H + R·2RO2· → (deactivation)

I φψk1k2k3

d[R·]/dt = 0 = Iφψ - k1[R·][O2] + k2[RO2·][RH]d[RO2·]/dt = 0 = k1[R·][O2] - k2[RO2·][RH] - k3[RO2·]2

[RO2·]2 = Iφψ / k3

-d[RH]/dt = Iφψ + k2[RH][RO2·]

Φapp = φψ + k2[RH](φψ / k3)0.5I-0.5B. Ohtani, Electrochemistry, 2014, 82, 414

65

square-root dependence

• Linear relations are obtained.• Y-intersect corresponding to Φ was negligible, i.e., very low intrinsic

quantum efficiency.• Appreciable photocatalytic activity might be due to long chain length.

Φap

pat

350

nm

I-0.5 / (mW cm-2)-0.5

TIO-2

Merck

0

0.2

0.4

0.6

0.8

0 0.5 1 1.5 2 2.5 3 3.5

Φapp = φψ + k2[RH](φψ / k3)0.5I -0.5

66

FB

2 µm

WML

200 nm 200 nm

500FB

200 nm 200 nm2 µm

WMH

500WML 500WMH

wetmill

773 K 773 K 773 K

20m2 g-1

42m2 g-1

43m2 g-1

8m2 g-1

15m2 g-1

15m2 g-1

effective particle size

67

！

activities

CH3COOH + 2O2→ 2CO2 + 2H2O

CH3OH → H2 + HCHO

4Ag+ + 2H2O→ O2 + 4Ag

CH3COOH + 2O2→ 2CO2 + 2H2O

68

possible band position of BWO/tungstena

VB

CB

TiO2

number of electrons for O2 reduction

1

(BWO)

1 2 2 0

1

24

WO3-Pt WO3BWO

69

2

1

0.5

WML

0.5

1

2

ln (R

/µm

ol h

-1)

FB

-5

-7

-9

-11-4 -2 0 2

ln (I /mW)86420-2

-2 0 2 4 6 8-4 864

-5

-7

-9

-11

light intensity-dependent rate by FB and WML

R = a I n → ln R = ln a + n ln I

1 µm 19.5 m2g-1

42.4 m2g-1100 nm

CH3COOH + 2O2 → 2CO2 + 2H2O

70

BWO + hν → BWO(e) Iψ1Φ first excitationBWO(e) + hν → BWO(2e) Iψ2Φ[BWO(e)] second excitationBWO(2e) + RH → BWO + R・ kr [BWO(2e)][RH] radical creationR・+ O2 → RO2・ ki [R・][O2] initiationRO2・+ RH → RO2H + R・ kp [RO2][RH] propagation2RO2・→ RO4R kt [RO2・]2 terminationBWO(e) → BWO kd [BWO(e)] deactivation

model for light intensity-dependent rate

BWO: photocatalyst BWO(e): BWO with e－ BWO(2e): BWO with 2e－I: light intensity Φ: quantum efficiency of e－ creationψ1: absorption efficiency of PC ψ2: absorption efficiency of PC(e)kr, ki, kp, kt ,kd: rate constants

assuming initiation only by 2 e－-bearing BWO (BWO(2e)) peroxy-radical chain mechanism

71

2

1

0.5

WML

0.5

1

2

ln (R

/µm

ol h

-1)

FB

-5

-7

-9

-11-4 -2 0 2

ln (I /mW)86420-2

-2 0 2 4 6 8-4 864

-5

-7

-9

-11


low I limit R = (α/kd0.5) I

high I limit R = (α/(ψ2φ)0.5) I 0.5 Ithr = kd/(ψ2φ)

4 mW 80 mW1 µm 19.5 m2g-1

42.4 m2g-1100 nm


72

(virtual) effective particle size = Ψ2for multielectron transfer processes

1 µm 19.5 m2g-1

42.4 m2g-1100 nm

×20

higher probability for accumulation of multiple electrons

73

70

35

0

500F

BFB

WM

L

WM

H

500W

ML

500W

MH

reac

tion

rate

/µm

ol h

-1activity of BWO samples for organics decomposition

1

0.5

1 2 3 4 5 6ln (I /mW)

ln (R

/µm

ol h

-1)

2

2

500FB

FB

0.5

1

-5

-6

-7

-8

-9

low I region R = Φkp[RH] (ψ1ψ2/kdkt)0.5 I

first-order low-intensity region


74

2

1

0.5

WML

0.5

1ln (R

/µm

ol h

-1)

FB

-5

-7

-9

-11-4 -2 0 2

ln (I /mW)86420-2

-2 0 2 4 6 8-4 864

-5

-7

-9

-11

2




4 mW 80 mW1 µm 19.5 m2g-1

42.4 m2g-1100 nm


！

75

visible light-sensitive Pt-WO3 photocatalystaction spectrum similar to diffuse reflectance spectrum

25

20

15

10

5

0550500450400350300

TiO2 P25 Pt-WO3

wavelength/nm

appa

rent

qua

ntum

effi

cien

cy/% 1.5

1.0

0.5

0.0550500450400350300

TiO2 WO3

wavelength/nm

Abs.

WO3

Pt

Pt

Abe, R.; Takami, H.; Murakami, N.; Ohtani, B., J. Am. Chem. Soc., 130, 7780–7781 (2008).

76

tungstena (WO3) with/without platinum (Pt)

77

VB(mainly orbital of

oxygen)

CB(mainly orbital of

titanium)

VB(mainly orbital of

sulfur)

CB(mainly orbital of

metal)

metal sulfide

band structure of metal oxides and sulfides

TiO2

metal oxide

level of one-electron oxygen

reduction

level of hydrogen production

WO3

78




ln (r

/μm

olh-

1cm

-2)

ln (IL /mW cm-2)

air

air

O2

79




ln (r

/μm

olh-

1cm

-2)

ln (IL /mW cm-2)

air

air

O2

80


rate at n = 0

diffusion of oxygen onto platinum

surface

81




ln (r

/μm

olh-

1cm

-2)

ln (IL /mW cm-2)

air

air

O2！

！

82

possible band position of BWO/tungstena

VB

CB

TiO2

number of electrons for O2 reduction

1 2 0

1

24

2

WO3-Pt

Pt

WO3BWO

83

ETDOSMETSEP





85

electrochemical equilibrium = simultaneous front/backward

n-electron transfer

nnumber of electrons

ΔG ＝－nFEE = E0 + ln(aOX/aR) × RT / nF

digital!

86

2

1

titania photocatalyzed oxygen evolution

singularity!

★★

★

87




ln (r

/μm

olh-

1cm

-2)

ln (IL /mW cm-2)

air

air

O2

singularity!

★★

★

88

2

1

0.5

WML

0.5

1ln (R

/µm

ol h

-1)

FB

-5

-7

-9

-11-4 -2 0 2

ln (I /mW)86420-2

-2 0 2 4 6 8-4 864

-5

-7

-9

-11

2




4 mW 80 mW1 µm 19.5 m2g-1

42.4 m2g-1100 nm


singularity!

★★

★

89

ETDOSMETSEP





90

electrochemical equilibrium = simultaneous front/backward

n -electron transfer

nnumber of electrons

digital!

91

2H2O + 4h+ → 4H+ + O2 4 1.23 V

2H2O + 2h+ → 2H+ + H2O2 1.76 VH2O2 + 2h+ → 2H+ + O2 2 0.70 V

H2O + h+ → H+ + HO・ 2.8 VHO・ + h+ + H2O → H+ + H2O2 1 1.14 V

H2O2 + h+ → H+ + HO2・ 1.51 VHO2・ + h+ → H+ + O2 (n ) －0.13 V

possible oxygen liberation processes

92


CB

VBh

e

How one SEP is chosen?

93

special orbital overlapping=

(no change in position)

+ energy overlapping=

(no change in energy)

photoexciation

electron transfer

both depends on

surface orbitals

singularity in a chemical reaction

related to particle sizedue to digitally controlled kinetics of

multielectron transfer

95


CB

VBh

e

h+

e－

SEP/標準電極電位standard electrode

potential

96

ETDOSMETSEP





to go beyond the band-structure model


format

Please send email in Japanese or English within 72 hoursto: [email protected]: pc2020MMDD-XXXXXXXX

[email protected](full name)(nickname)(what is learnt in this lecture series) + (questions if any)[blank line](answer for question 1)(answer for question 2)(answer for question 3)・・


email example

to

subject

(same as subject)email addressfull namenicknamecomment(s) +

question(blank line)answer 1answer 2answer 3・・

pc20200813-57388301

pc20200813-57388301

pc20200813-57388301


special report (20 + α points)

special report for extra (bonus) score (20 point)report on critical review on "photocatalysis" in Wikipedia, pointing out errors, misunderstanding and speculationsbased on the contents of this lecture.http://en.wikipedia.org/wiki/Photocatalysishttp://ja.wikipedia.org/wiki/光触媒

• Japanese or English• A4 size 2 pages• submission by email attachment• a PDF file is more preferable than a Word file• email title: pc20200820-XXXXXXXX• file name: pc20200820-XXXXXXXX.pdf (or .docx or .doc)• deadline of submission: August 20, 2020 23:59

集合写真!group photo

pcat.cat.hokudai.ac.jppcat.cat.hokudai.ac.jp/class/pc2020/20200813_bo_sapporo.pdf2020/08/13 ·...

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