TY - JOUR

T1 - Effect of the TiO2–ZnO Heterostructure on the Photoinduced Hydrophilic Conversion of TiO2 and ZnO Surfaces

AU - Rudakova, Aida V.

AU - Emeline, Alexei V.

AU - Bahnemann, Detlef

N1 - Funding Information: The present study was performed within the project “Establishment of the Laboratory ‘Photoactive Nanocomposite Materials’” no. 14.Z50.31.0016 supported by a Mega Grant of the Government of the Russian Federation and a research grant of the Saint Petersburg State University (Pure ID 39054581). A.V.R. thanks the RFBR no. 18-03-00855\18 grant, which supported the studies of photoinduced hydrophilicity of composite thin films. The authors are also grateful to the RC “Nanophotonics” (personally to Dr. Maxim Lozhkin), RC “Nanotechnology” (personally to Dr. Vladimir Mikhailovski), RC “X-ray Diffraction Studies” (personally to Dr. Igor Kasatkin), and RC “Centre for Physical Methods of Surface Investigation” (personally to Dr. Alexandra Koroleva) of the Research Park at Saint Petersburg State University for the helpful assistance in conducting synthesis and characterization of the samples. The authors thank Dr. Evgenii Ubyivovk for performing the TEM analysis.

PY - 2019/4/11

Y1 - 2019/4/11

N2 - The present study demonstrates the effect of the composition and structure of TiO 2-ZnO heterostructured coatings on the photoinduced hydrophilic conversion of TiO 2 and ZnO surfaces. It has been observed that the kinetic parameters of the photoinduced hydrophilic conversion can be significantly changed. Based on the analysis of the experimental data and the proposed mechanism, it is concluded that the ratio between the surface concentrations of electrons and holes participating in the photoinduced generation and deactivation of hydrophilic surface sites plays the major role in this alteration of the surface hydrophilicity of such heterostructured coatings. The ratio between the surface concentrations of electrons and holes can be changed considerably by the formation of the so-called type II heterojunction between TiO 2 and ZnO, yielding an effective charge separation. The proposed approach based on the creation of these type II heterostructures seems to be promising and productive both for fundamental studies of the photoinduced surface superhydrophilicity and for the application of self-cleaning coatings with controlled wettability.

AB - The present study demonstrates the effect of the composition and structure of TiO 2-ZnO heterostructured coatings on the photoinduced hydrophilic conversion of TiO 2 and ZnO surfaces. It has been observed that the kinetic parameters of the photoinduced hydrophilic conversion can be significantly changed. Based on the analysis of the experimental data and the proposed mechanism, it is concluded that the ratio between the surface concentrations of electrons and holes participating in the photoinduced generation and deactivation of hydrophilic surface sites plays the major role in this alteration of the surface hydrophilicity of such heterostructured coatings. The ratio between the surface concentrations of electrons and holes can be changed considerably by the formation of the so-called type II heterojunction between TiO 2 and ZnO, yielding an effective charge separation. The proposed approach based on the creation of these type II heterostructures seems to be promising and productive both for fundamental studies of the photoinduced surface superhydrophilicity and for the application of self-cleaning coatings with controlled wettability.

UR - http://www.scopus.com/inward/record.url?scp=85064333545&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.8b12125

DO - 10.1021/acs.jpcc.8b12125

M3 - Article

VL - 123

SP - 8884

EP - 8891

JO - The Journal of Physical Chemistry C

JF - The Journal of Physical Chemistry C

IS - 14

ER -