Mechanistic Investigations of Photoelectrochemical Water and Methanol Oxidation on Well-Defined TiO2 Anatase (101) and Rutile (110) Surfaces

被引：20

作者：

Ahmed, Amira Y. ^{[1
]}

Kandiel, Tarek A. ^{[2
,3
]}

Oekermann, Torsten ^{[4
,7
]}

Guennemann, Carsten ^{[5
]}

Bahnemann, Detlef ^{[5
,6
]}

机构：

[1] Sohag Univ, Fac Sci, Dept Chem, Sohag 82524, Egypt

[2] King Fahd Univ Petr & Minerals, Dept Chem, Dhahran 31261, Saudi Arabia

[3] KA CARE Energy Res & Innovat Ctr Dhahran, Dhahran 31261, Saudi Arabia

[4] Leibniz Univ Hannover, Inst Phys Chem & Electrochem, Callinstr 3A, D-30167 Hannover, Germany

[5] Leibniz Univ Hannover, Inst Tech Chem, Photocatalysis & Nanotechnol Res Unit, Callinstr 3A, D-30167 Hannover, Germany

[6] St Petersburg State Univ, Dept Photon, Fac Phys, Lab Nanocomposite Mat, Ulianovskaia Str 3, St Petersburg 198504, Russia

[7] Friemann & Wolf Batterietech GmbH, Ind Str 22, D-63654 Buedingen, Germany

来源：

ACS APPLIED ENERGY MATERIALS | 2019年 / 2卷 / 07期

关键词：

anatase (101); single crystal; rutile (110); water oxidation; photocatalysis; IMPS; PHOTOCATALYTIC ACTIVITIES; QUANTUM YIELD; HYDROGEN; FORMALDEHYDE; ADSORPTION; ELECTRODES; LIGHT;

D O I：

10.1021/acsaem.9b01163

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The mechanisms of photoelectrochemical water and methanol oxidation on TiO2 anatase (101) and rutile (110) surfaces have been studied using the intensity modulated photocurrent spectroscopy (IMPS) technique. The phenomenological rate constants for the photogenerated charge carriers transfer and recombination have been determined at different band bending values in the presence and absence of methanol as well as at different methanol concentrations. The obtained results have been analyzed based on the IMPS theory for a bulk semiconductor surface together with a model to define the nature of the surface-bound intermediates. The results of the analysis indicated that (i) water oxidation proceeds via coupling of two >OHbr center dot radicals on both surfaces and the coupling of >OHbr center dot radicals is about 1 order of magnitude faster on the anatase (101) surface than that on the rutile (110) surface; (ii) the rate constant of surface recombination at the flatband potential on anatase (101) surface is much lower than that on rutile (110) surface; and (iii) in the presence of methanol, the coupling of the >OHbr center dot radicals on the anatase (101) surface is still the dominating reaction whereas on the rutile (110) surface the photogenerated >OHbr center dot reacts rapidly with methanol, faster by a factor of 18 times than on anatase (101) surface so that the >OHbr center dot coupling is less dominant. On the basis of those findings, it is concluded that the coupling of the>OHbr center dot radicals is an essential step to trap the photogenerated holes and reduce the surface recombination on anatase (101) surface in the absence and presence of methanol. The faster reaction of methanol with the >OHbr center dot on rutile (110) compared with that on anatase (101), while the former usually exhibits lower photocatalytic activity, indicates that the charge separation (not the charge transfer) is the rate controlling step in the photocatalytic process.

引用

页码：5308 / 5318

页数：21

共 44 条

[1] Comparison of the photoelectrochemical oxidation of methanol on rutile TiO2 (001) and (100) single crystal faces studied by intensity modulated photocurrent spectroscopy [J].