Recent Advances in Development of Antimicrobial Textiles
145
Fig. 12 Schematic illustration of photocatalytic degradation of bacterium
1.7 eV band-gap energy. Electron hole pair is formed with photon energies exceeding
the band-gap of CuO under irradiation. The excited e
− s react with O 2 forming O 2
•−
radical [105], that is responsible for bacterial inactivation.
CuO + hν(<660 nm) → CuO
e cb
−
, h vb
+
(1)
CuO produced electron and hole pair (e cb
− , h vb
+ ) with photon energies greater
than band-gap energy of CuO as given in Eq. (1). Thus produced excited electron
(e cb
− ) can either react with (1) directly the atmospheric O 2 forming O
•−2 (Eq. 2)
or (2) by reducing the Cu
2+ to Cu
+ as shown in Eq. (3) that on reacting with O 2
converted into CuO (Cu
2+ ) [105] shown in Eq. (4).
CuO
e cb
−
+ O 2 → CuO + O
•−2
(2)
CuO
e cb
−
→ CuO
Cu
+
(3)
CuO
Cu
+
+ O 2 → CuO
Cu
2+
(4)
Overall reaction is given in Eq. (5). And generated O
•−2 radical is responsible for
antibacterial activity.
CuO
Cu
+
+ O 2 → CuO
Cu
2+
+ O
•−2
(5)