TY - JOUR

T1 - TiO2-reduced graphene oxide nanocomposites

T2 - Microsecond charge carrier kinetics

AU - Tolosana-Moranchel, A.

AU - Faraldos, M.

AU - Bahamonde, A.

AU - Pascual, L.

AU - Sieland, F.

AU - Schneider, J.

AU - Dillert, R.

AU - Bahnemann, D.W.

N1 - Funding Information: This work has been supported by the Spanish Plan Nacional de I+D+i through the project CTM2015-64895-R. Alvaro Tolosana-Moranchel thanks to Ministerio de Educación, Cultura y Deporte for his FPU grant ( FPU14/01605 ) and ( EST16/00065 ). The authors are also grateful to Technical Research Support Unit of Instituto de Catálisis y Petroleoquímica (CSIC).

PY - 2020/1/1

Y1 - 2020/1/1

N2 - In this work, transient absorption spectroscopy studies in the microsecond time scale were carried out to investigate the dynamics of photogenerated electron-hole pairs in TiO 2-rGO nanocomposites, prepared by a hydrothermal method, under different atmospheres: N 2, O 2, and N 2 saturated in CH 3OH. Under N 2 atmosphere, the transient absorption signal detected in the region between 450 and 700 nm dropped as the rGO mass concentration in the composite was raised. The electron transfer from TiO 2 to rGO was confirmed by using a model based on fractal surfaces which describes the decay kinetics. In the presence of methanol as hole acceptor, P25-rGO 0.5% and 1% were able to reach the maximum transient absorption faster than the other studied nanocomposites. However, after 10 μs, the P25-rGO 0.1% nanocomposite yielded the highest transient absorption signal and the best conversion and initial reaction rate in the photocatalytic degradation of dichloroacetic acid in aqueous suspensions. The effect of rGO on free electrons was investigated by detecting the transient signal at 980 nm under N 2 saturated in CH 3OH, for the different samples. It was found that the measured signals followed the same response than at 660 nm further evincing the electron transfer process. No sensitization effect of rGO was observed when the samples were excited at 450 nm.

AB - In this work, transient absorption spectroscopy studies in the microsecond time scale were carried out to investigate the dynamics of photogenerated electron-hole pairs in TiO 2-rGO nanocomposites, prepared by a hydrothermal method, under different atmospheres: N 2, O 2, and N 2 saturated in CH 3OH. Under N 2 atmosphere, the transient absorption signal detected in the region between 450 and 700 nm dropped as the rGO mass concentration in the composite was raised. The electron transfer from TiO 2 to rGO was confirmed by using a model based on fractal surfaces which describes the decay kinetics. In the presence of methanol as hole acceptor, P25-rGO 0.5% and 1% were able to reach the maximum transient absorption faster than the other studied nanocomposites. However, after 10 μs, the P25-rGO 0.1% nanocomposite yielded the highest transient absorption signal and the best conversion and initial reaction rate in the photocatalytic degradation of dichloroacetic acid in aqueous suspensions. The effect of rGO on free electrons was investigated by detecting the transient signal at 980 nm under N 2 saturated in CH 3OH, for the different samples. It was found that the measured signals followed the same response than at 660 nm further evincing the electron transfer process. No sensitization effect of rGO was observed when the samples were excited at 450 nm.

KW - Charge carrier dynamics

KW - Fractal kinetic model

KW - Reduced graphene oxide

KW - TiO -rGO

KW - Transient absorption spectroscopy

UR - http://www.scopus.com/inward/record.url?scp=85073011549&partnerID=8YFLogxK

U2 - 10.1016/j.jphotochem.2019.112112

DO - 10.1016/j.jphotochem.2019.112112

M3 - Article

VL - 386

JO - Journal of Photochemistry and Photobiology A: Chemistry

JF - Journal of Photochemistry and Photobiology A: Chemistry

SN - 1010-6030

M1 - 112112

ER -