Page 576 - eProceeding for IRSTC2017 and RESPeX2017

Masbah / JOURNAL ONLINE JARINGAN COT POLIPD

These energies correspond to electromagnetic waves having frequencies in the region of the near UV,
therefore only near UV photons can effectively promote charge separation in TiO crystals. In principle, a
2
photo-catalytic reaction may proceed on the surface of TiO via several steps, namely: (i) production of
2
photo-generated electron-hole pairs by exciting the semiconductor with light; (ii) separation of electrons and
holes by traps available on the TiO surface; (iii) redox process induced by the separated electrons and holes
2
with the adsorbates (electron acceptors and electron donors) present on the surface; and (iv) desorption of the
products and reconstruction of the surface. In semiconductor TiO the energy of the incoming photons is
2
used to excite the electrons from band valence to conduction band and created the electron-hole pairs. The
following scheme are given below [2]:
 – +
TiO + h e + h (1)
2
2H 2 O + 4H + O 2 + 4H + (2)

2H + 2e H (3)
2

The total reaction is
2 H 2 O + 4 h  O 2 + 2 H 2 (4)
Organicmat. + O 2  CO 2
+ H 2O + mineral acid (5)
H O
2
Diagram of mechanism of splitting are given in Figure 1

H O
2

H 2

O 2

Figure 1 :Diagram of water splitting mechanism

The absorption coefficient of TiO as function of photon energy was measured and plotted in
2
Figure 2.
14
Absorption Coeficient (x 104 10
12

8
)
-1
cm
6
4

2

0
0 2 4 6
Photon Energy (eV)

Figure 2. The absorption coefficient a function of photon energy (eV) in TiO .
2

The calculation of the rate carrier generation was given by Zeghboeck, B. [2]in equation :

G G
p,light n,light 
 
P (x) P (x) E A
opt opt ph

573 | V O L 1 1 - I R S T C 2 0 1 7 & R E S P E X 2 0 1 7