TY - JOUR

T1 - Influence of the Dopant Concentration on the Photoelectrochemical Behavior of Al-Doped TiO2

AU - Murashkina, Anna A.

AU - Rudakova, Aida V.

AU - Ryabchuk, Vladimir K.

AU - Nikitin, Konstantin V.

AU - Mikhailov, Ruslan V.

AU - Emeline, Alexei V.

AU - Bahnemann, Detlef W.

PY - 2018/4/12

Y1 - 2018/4/12

N2 - In the present study, we explored the effect of Al-dopant concentration within the range of <1.1 wt % on the photoelectrochemical (PEC) activity of an Al-doped TiO2 photoanode. The experimental dependencies of PEC efficiency on Al-dopant concentration indicate that there is an optimal Al concentration of 0.5 wt % corresponding to the highest photoactivity. The analysis of the spectral dependencies of the photocurrent confirms that 0.5 wt % Al provides the highest activity at photoexcitation in both intrinsic and extrinsic absorption spectral range. It was also shown that Al doping does not affect the optical band gap of TiO2. The dependence of PEC activity on Al concentration correlates with the corresponding dependencies of the flat-band potential and work function, indicating the Fermi-level shift toward the conduction band for the Al concentration <0.5 wt % and toward the valence band for the Al concentration >0.5 wt %. Such alteration of the Fermi-level position is explained in terms of alteration of the type of major compensating intrinsic defects from [Vo••-TiTi′] for the Al concentration <0.5 wt % acting as shallow traps to [AlTi′-Vo••-AlTi′]× for the Al concentration >0.5 wt % acting as deep traps. Transformation of compensating defects from shallow traps, which are ineffective in charge recombination processes, to deep traps, which act as effective recombination centers, is responsible for the optimal dopant concentration, 0.5 wt %, to achieve the higher PEC activity of Al-doped TiO2.

AB - In the present study, we explored the effect of Al-dopant concentration within the range of <1.1 wt % on the photoelectrochemical (PEC) activity of an Al-doped TiO2 photoanode. The experimental dependencies of PEC efficiency on Al-dopant concentration indicate that there is an optimal Al concentration of 0.5 wt % corresponding to the highest photoactivity. The analysis of the spectral dependencies of the photocurrent confirms that 0.5 wt % Al provides the highest activity at photoexcitation in both intrinsic and extrinsic absorption spectral range. It was also shown that Al doping does not affect the optical band gap of TiO2. The dependence of PEC activity on Al concentration correlates with the corresponding dependencies of the flat-band potential and work function, indicating the Fermi-level shift toward the conduction band for the Al concentration <0.5 wt % and toward the valence band for the Al concentration >0.5 wt %. Such alteration of the Fermi-level position is explained in terms of alteration of the type of major compensating intrinsic defects from [Vo••-TiTi′] for the Al concentration <0.5 wt % acting as shallow traps to [AlTi′-Vo••-AlTi′]× for the Al concentration >0.5 wt % acting as deep traps. Transformation of compensating defects from shallow traps, which are ineffective in charge recombination processes, to deep traps, which act as effective recombination centers, is responsible for the optimal dopant concentration, 0.5 wt %, to achieve the higher PEC activity of Al-doped TiO2.

KW - VISIBLE-LIGHT

KW - PHOTOCATALYTIC ACTIVITY

KW - TITANIUM-DIOXIDE

KW - WATER PHOTOLYSIS

KW - RUTILE

KW - PHOTOANODES

KW - ABSORPTION

KW - ORIGIN

KW - GROWTH

UR - http://www.scopus.com/inward/record.url?scp=85045376059&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/influence-dopant-concentration-photoelectrochemical-behavior-aldoped-tio2

U2 - 10.1021/acs.jpcc.7b12840

DO - 10.1021/acs.jpcc.7b12840

M3 - Article

AN - SCOPUS:85045376059

VL - 122

SP - 7975

EP - 7981

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 14

ER -