Single Crystal Materials as Photoanodes

4 Single Crystal Materials as Photoanodes 4.4.1 Crystalline n-Ti02 

Inhibition of H2 formation can be seen when the anode-volume is saturated with O2 application of an external bias up to 0.7 V can usually prevent this effect, increased yield of H2 when Pt is present as a cathode has been rationalized in terms of three factors (a) the removal of conduction band electron from Ti02 to Pt [equation (4.4.14)], (b) The ease of reactions (4.4.15) and (4.4.16) because of a low overpotential for H2 evolution from water at the Pt cathode, and (c) H atom migration to the Pt cathode. 

This leads to an increase in the concentration of the majority (electron) carriers and therefore the conductivity. The photocurrent densities sometimes vary due to incomplete dissolution as well as large dopant concentrations [10]. Raising the sintering temperature of Ti02 Nb to 1350°C and maintaining the doping concentration ND/[Ti j in the range of 0.05 at%, leads to an increase in photocurrent by a factor three [11]. 

SrTiOs is a mechanically and chemically robust material with a simple perovskite structure. N-type SrTiOz can be achieved by reducing it with Hz for 4h at 1050-1100°C the resulting single 

Crystalline Sn02 and WO3 photoanodes for water photoelectrolysis have been reported [24-26], The band gap of Sn02 (Erg = 3.5 eV) makes single crystals of this material of little interest with respect to solar induced optical properties. Wrighton and coworkers observed 

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