A novel idea of enhancing the separation of electron and hole is the
P–N junction concept. In this concept, the contact between a p-type
material with its n-type counterpart will induce an internal electric
field that can extend the probability of electron–hole separation.
Similar concept has been reported by Shifu et al. for NiO-doped TiO
[9], and Liu et al. for V-doped TiO
[10].
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