ELECTROCHEMICAL CHARACTERIZATION OF NANOSTRUCTURED DIAMOND LAYERS FOR

ENERGY CONVERSION APPLICATION

Silviya Pehlivanova

ОПЕРАТИВНА ПРОГРАМА„РАЗВИТИЕ НА ЧОВЕШКИТЕ РЕСУРСИ“

ПРОЕКТ BG051PO001-3.3.06-0014ЦЕНТЪР ПО МАТЕМАТИЧНО МОДЕЛИРАНЕ И КОМПЮТЪРНА

СИМУЛАЦИЯ ЗА ПОДГОТОВКА И РАЗВИТИЕ НА МЛАДИ ИЗСЛЕДОВАТЕЛИ

Европейски социален фондЕвропейски съюз

Use of Solar energyConversion of solar energy into electricity by artificial photosynthesis

natural photosynthesis artificial photosynthesis

Efficient use of sunlight Materials with improved physical, chemical and biological properties

MaterialsDiamond Phthalocyanine (PhC) Structure and properties of the

diamond

Nanocrystalline diamond layers (NCD)

Diamond layers doped with boron

Organic dyes PhotosensitivityHigh chemical and thermal

stability

NCD+PhC Chlorophyll

Sequence of the experiment

1. Deposition of nanocrystalline layers

2. Modification of diamond surfaces

- O2-plasma - NH3-plasma

- UV/O3-treatment

3. Immobilization with photosensitive molecules

4. Analyzing the effectiveness of the modification

- Measurement of contact angles

- X-ray photoelectron spectroscopy

- Raman spectroscopy

5. Fotoelektrochemical research

Deposition of diamond layers Substrate preparation Hot-Filament CVD-method Operating parameters (gas Mixture 1% CH4 + 99% H2)

Substrate’s Temperature

Filament’s Temperature

PressureTime

880…890 °C > 2000 °C 25 mbar 180 min

NCD-layer HFCVD-installation

Modification of diamond layers

Immobilization with photosensitive molecules (Why Phthalocyanines? )

Immobilization of

Mn-PhC

-Preparation of the solution

-Treatment of the NCD-layers (about 12 hours)

chlorophyll Mn-phthalocyanine

(C96H144ClMnN8S8 )

Fotoelektrochemical characterisationProducing of diamond electrodes

•P-doped NCD-layers

•Immobilization of phthalocyanine

Testing

•Performance of the experiments

•Three-electrode cell

•PBS-solution as electrolyte

NCD-electrodes and a using light source

Three-electrode cell

Cyclic voltammetry

• Cyclic curves of unmodified NCD-sample without phthalocyanine

• Under  illumination the electrode surface is stable and changes are not observed

-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000 3000

-12

-10

-8

-6

-4

-2

0

2

4

6

8

in the dark under illumination

I, m

A

E, mV

unmodified sample without PhC

(C80H96ClMnN8О16)

Cyclic voltammetry

• Cyclic curves of NCD-sample with phthalocyanine under and without illumination

• There is a difference between the measurements obtained in dark and under illumination

• The voltammetric curves clearly indicate both oxidation and reduction processes answerable for the detected photocurrent.

unmodified sample with PhC

(C80H96ClMnN8О16)

-3000 -2000 -1000 0 1000 2000

-3

-2

-1

0

1

2

3

4

5

6

in the dark under illumination

I, m

A

E, mV

El-d 2a, -2.5V - +1.8V, 100 mVs,

Change of the electrochemical potential with time for short-duration illumination

0 200 400 600 800 1000 1200 1400 1600 18000

20

40

60

80

100

120

140

160

180

200

Pot

entia

l, m

V

Time, sec

turn

on

turn

off

• Change of the potential at every switch on and off of the light source

• The obtained results show that the functionalized diamond films are photosensitive

THANK YOU FOR YOUR ATTENTIONTHANK YOU FOR YOUR ATTENTION

ОПЕРАТИВНА ПРОГРАМА„РАЗВИТИЕ НА ЧОВЕШКИТЕ РЕСУРСИ“

ПРОЕКТ BG051PO001-3.3.06-0014ЦЕНТЪР ПО МАТЕМАТИЧНО МОДЕЛИРАНЕ И КОМПЮТЪРНА

СИМУЛАЦИЯ ЗА ПОДГОТОВКА И РАЗВИТИЕ НА МЛАДИ ИЗСЛЕДОВАТЕЛИ

Европейски съюз Европейски социален фонд