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Photocatalytic Reduction of Carbon Dioxide Using Heterostructure CdS-TiO2

Photocatalyst to Hydrocarbon

Supervisor : Xin Feng

Reporter： Song Guixian

2013/03/27

Contents

Photocatalytic reduction of CO2 reaction process

Selected catalyst

Catalyst preparation

Scheme of prepared catalyst

Next plans

Photocatalytic reduction of CO2 reaction process

OH +h+ O +H+

O +h+ O +H+

H+ +e- HCO2+e-

CO2- +2 +2h+ HCOOHH

CO2-

Catalyst h++e-h¦Í

Photocatalytic reduction of CO2 reaction process

+CO2h¦Í

O +HCOOHOHcatalyst

+HCOOHhν

OHcatalyst

HCOO +H2O

Selected catalyst

OH O-2H+

E0ox=0.85V vs.NHE

CO2+2e-+2H+ HCOOHE0

red=-0.61V vs.NHE

Oxidation process of cyclohexanol

Reduction process of carbon dioxide

Selected catalyst

TiO2

CdS

-

-

+

+

e-

h¦Í

CB

VB

CB

VB

Heterostructure CdS-TiO2 photocatalyst CdS with band gap of 2.4 eV （ CB， -1.0V；VB， 1.4V， vs NHE at pH =7.0）， TiO2 with band gap of 3.2eV （ CB， -0.5V； VB， 2.7V， vs NHE at pH =7.0）

Fig.1. The mechanism of photocatalytic reduction of CO2

Scheme of prepared catalyst

Fig.2. The grow process of heterostructure CdS-TiO2 photocatalyst

Catalyst preparationPrepared TiO2

Tetrabutyl titanate +acetic acid

Precursor solution

Hydrothermalsynthesis

Centrifugation

Dry Calcination toDetach impurity

Product

Catalyst preparationPrepared CdS-TiO2

Ultrasonic dispersion

Titanium dioxide + deionized water

Stir

CdCl2 ·2.5H2O aqueous solution

Precursor solution

Na2S ·9H2O aqueous solution

In situ hydrothermal

Centrifugation

Dry

Product

Characterization of UV–vis absorbance spectra

Fig. 3. The UV–visible diffuse reflectance spectra of the samples

200 300 400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6A

bsor

banc

e

Wave length(nm)

T1 T2 P25 CdSCdS-P25 CdS-T2(25%) CdS-T2(20%)

Next plans

1. Optimization of reaction conditions adopt single factor experiment.

2. The samples will be characterized on SEM、TEM、 XRD、 PL.

3. Photocatalytic reduction of CO2 reaction will be carried out.

4. Product will be analyzed by GC-MS and GC.

THANK YOU FOR YOUR ATTENTION !