TY - JOUR

T1 - TiO2 photocatalysis

T2 - Impact of the platinum loading method on reductive and oxidative half-reactions

AU - Al-Madanat, Osama

AU - Curti, Mariano

AU - Günnemann, Carsten

AU - AlSalka, Yamen

AU - Dillert, Ralf

AU - Bahnemann, Detlef W.

N1 - Funding Information: Financial support from the Katholischer Akademischer Ausländer-Dienst ( KAAD ) and Graduiertenakademie at Gottfried Wilhelm Leibniz Universität Hannover are gratefully acknowledged for providing scholarships for Osama Al-Madanat to perform his Ph.D. Mariano Curti is grateful to the DAAD together with the Ministerio de Educación, Cultura, Ciencia y Tecnología (Argentina) for his ALEARG scholarship. Yamen Alsalka gratefully acknowledges the financial support from the Deutscher Akademischer Austauschdienst (DAAD) and the Federal Foreign Office.

PY - 2021/11/15

Y1 - 2021/11/15

N2 - Environmental pollution and shortage of energy resources are considered as the most serious threats faced by mankind. Heterogeneous photocatalysis has become one of the most frequently investigated technologies, thanks to its dual ability to convert solar energy into chemical energy and to perform environmental remediation. However, the low quantum efficiencies achieved so far with TiO2 photocatalysts represent a big challenge that needs to be overcome before their potential can be fully realized. Among other possibilities, the loading of noble metals (e.g. platinum) is a proven strategy to enhance the TiO2 photoactivity. However, the method by which Pt/TiO2 is prepared appears to play a crucial role in tuning the photocatalytic activity. In this work, platinum-loaded anatase TiO2 photocatalysts were prepared using two alternative methods: photodeposition by reduction of PtCl62- and physical mixing of TiO2 with Pt nanoparticles synthesized by laser ablation. The effect of the Pt deposition method was evaluated for the photoreforming reaction of two organic substrates: naphthalene, and methanol. To explain the different activities, a full physicochemical characterization was performed for these samples. Moreover, the charge carrier dynamics in pristine and platinized TiO2 were investigated by transient absorption spectroscopy (TAS), and by the electron paramagnetic resonance (EPR) technique, respectively. The photodeposition of Pt caused a significant decrease in the charge carrier recombination rates, which in turn led to an increased rate of the photocatalytic reactions. This effect was mainly attributed to the strong metal-semiconductor interaction resulting from the photodeposition process, aided by the preferential deposition on crystalline facets with stronger reducing properties.

AB - Environmental pollution and shortage of energy resources are considered as the most serious threats faced by mankind. Heterogeneous photocatalysis has become one of the most frequently investigated technologies, thanks to its dual ability to convert solar energy into chemical energy and to perform environmental remediation. However, the low quantum efficiencies achieved so far with TiO2 photocatalysts represent a big challenge that needs to be overcome before their potential can be fully realized. Among other possibilities, the loading of noble metals (e.g. platinum) is a proven strategy to enhance the TiO2 photoactivity. However, the method by which Pt/TiO2 is prepared appears to play a crucial role in tuning the photocatalytic activity. In this work, platinum-loaded anatase TiO2 photocatalysts were prepared using two alternative methods: photodeposition by reduction of PtCl62- and physical mixing of TiO2 with Pt nanoparticles synthesized by laser ablation. The effect of the Pt deposition method was evaluated for the photoreforming reaction of two organic substrates: naphthalene, and methanol. To explain the different activities, a full physicochemical characterization was performed for these samples. Moreover, the charge carrier dynamics in pristine and platinized TiO2 were investigated by transient absorption spectroscopy (TAS), and by the electron paramagnetic resonance (EPR) technique, respectively. The photodeposition of Pt caused a significant decrease in the charge carrier recombination rates, which in turn led to an increased rate of the photocatalytic reactions. This effect was mainly attributed to the strong metal-semiconductor interaction resulting from the photodeposition process, aided by the preferential deposition on crystalline facets with stronger reducing properties.

KW - Charge carrier dynamics

KW - H production

KW - Photoreforming

KW - Polycyclic aromatic hydrocarbons

KW - Preparation method

KW - Titania

UR - http://www.scopus.com/inward/record.url?scp=85111562092&partnerID=8YFLogxK

U2 - 10.1016/j.cattod.2021.07.013

DO - 10.1016/j.cattod.2021.07.013

M3 - Article

AN - SCOPUS:85111562092

VL - 380

SP - 3

EP - 15

JO - Catalysis Today

JF - Catalysis Today

SN - 0920-5861

ER -