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Catalysts
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Photo-Induced Electron Transfer Kinetics in Catalysis
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Photo-Induced Electron Transfer Kinetics in Catalysis

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Computational Catalysis".

Deadline for manuscript submissions: closed (15 October 2020) | Viewed by 12670

Special Issue Editors

Dr. Stephan Kupfer

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Guest Editor
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, D-07743 Jena, Germany
Interests: quantum chemistry; photo-induced electron transfer; photo-induced energy transfer; photochemistry; photophysics; plasmon-enhanced spectroscopy
Dr. Martin Richter

E-Mail Website
Guest Editor
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, D-07743 Jena, Germany
Interests: quantum chemistry; charge transfer; excitation energy transfer; molecular dynamics; dissipative quantum dynamics; nonlinear spectroscopy
Dr. Alexander Schubert

E-Mail Website
Guest Editor
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, D-07743 Jena, Germany
Interests: theoretical chemistry; quantum dynamics; nonlinear spectroscopy; charge and energy transfer; organic photovoltaics; photosynthesis

Special Issue Information

Dear Colleagues,

Electron transfer processes are of outstanding importance in various natural systems as well as in countless artificial applications. Biological electron transfer chains of metalloporphyrins and their derivatives, for example, guide photo-generated charges efficiently towards the catalytic site in the photosynthesis process. In various optoelectronic applications, on the other hand, photo-induced charge transfer phenomena are of paramount importance and initiate, for example, in dye-sensitized solar cells catalytic reactions. Beyond photovoltaic applications, light-harvesting inspired by nature aims to generate high energy compounds by utilizing a unidirectional photo-induced energy and subsequent charge transfer to relocate one or multiple electrons towards a catalytically active site, where reduction leads to formation of molecular hydrogen or other high energy compounds.

This Special Issue aims to cover recent progress and advances in the field of electron transfer kinetics in photocatalysis. This topic covers experimental and theoretical studies to elucidate the dynamics of (light-driven) electron and energy transfer processes in biological as well as artificial light-harvesting systems.

Dr. Stephan Kupfer
Dr. Martin Richter
Dr. Alexander Schubert
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • electron transfer kinetics
  • energy transfer kinetics
  • photocatalysis
  • quantum chemical simulation
  • quantum dynamics
  • molecular dynamics
  • time-resolved spectroscopy
  • (spectro-)electrochemistry

Published Papers (4 papers)

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Research

14 pages, 3634 KiB  
Article
Investigating Light-Induced Processes in Covalent Dye-Catalyst Assemblies for Hydrogen Production
by Sebastian Bold, Tatiana Straistari, Ana B. Muñoz-García, Michele Pavone, Vincent Artero, Murielle Chavarot-Kerlidou and Benjamin Dietzek
Catalysts 2020, 10(11), 1340; https://doi.org/10.3390/catal10111340 - 18 Nov 2020
Cited by 8 | Viewed by 2472
Abstract
The light-induced processes occurring in two dye-catalyst assemblies for light-driven hydrogen production were investigated by ultrafast transient absorption spectroscopy. These dyads consist of a push-pull organic dye based on a cyclopenta[1,2-b:5,4-b’]dithiophene (CPDT) bridge, covalently linked to two different H2-evolving cobalt catalysts. [...] Read more.
The light-induced processes occurring in two dye-catalyst assemblies for light-driven hydrogen production were investigated by ultrafast transient absorption spectroscopy. These dyads consist of a push-pull organic dye based on a cyclopenta[1,2-b:5,4-b’]dithiophene (CPDT) bridge, covalently linked to two different H2-evolving cobalt catalysts. Whatever the nature of the latter, photoinduced intramolecular electron transfer from the excited state of the dye to the catalytic center was never observed. Instead, and in sharp contrast to the reference dye, a fast intersystem crossing (ISC) populates a long-lived triplet excited state, which in turn non-radiatively decays to the ground state. This study thus shows how the interplay of different structures in a dye-catalyst assembly can lead to unexpected excited state behavior and might open up new possibilities in the area of organic triplet sensitizers. More importantly, a reductive quenching mechanism with an external electron donor must be considered to drive hydrogen production with these dye-catalyst assemblies. Full article
(This article belongs to the Special Issue Photo-Induced Electron Transfer Kinetics in Catalysis)
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23 pages, 2512 KiB  
Article
Influence of Surface Ligands on Charge-Carrier Trapping and Relaxation in Water-Soluble CdSe@CdS Nanorods
by Mathias Micheel, Bei Liu and Maria Wächtler
Catalysts 2020, 10(10), 1143; https://doi.org/10.3390/catal10101143 - 3 Oct 2020
Cited by 16 | Viewed by 4364
Abstract
In this study, the impact of the type of ligand at the surface of colloidal CdSe@CdS dot-in-rod nanostructures on the basic exciton relaxation and charge localization processes is closely examined. These systems have been introduced into the field of artificial photosynthesis as potent [...] Read more.
In this study, the impact of the type of ligand at the surface of colloidal CdSe@CdS dot-in-rod nanostructures on the basic exciton relaxation and charge localization processes is closely examined. These systems have been introduced into the field of artificial photosynthesis as potent photosensitizers in assemblies for light driven hydrogen generation. Following photoinduced exciton generation, electrons can be transferred to catalytic reaction centers while holes localize into the CdSe seed, which can prevent charge recombination and lead to the formation of long-lived charge separation in assemblies containing catalytic reaction centers. These processes are in competition with trapping processes of charges at surface defect sites. The density and type of surface defects strongly depend on the type of ligand used. Here we report on a systematic steady-state and time-resolved spectroscopic investigation of the impact of the type of anchoring group (phosphine oxide, thiols, dithiols, amines) and the bulkiness of the ligand (alkyl chains vs. poly(ethylene glycol) (PEG)) to unravel trapping pathways and localization efficiencies. We show that the introduction of the widely used thiol ligands leads to an increase of hole traps at the surface compared to trioctylphosphine oxide (TOPO) capped rods, which prevent hole localization in the CdSe core. On the other hand, steric restrictions, e.g., in dithiolates or with bulky side chains (PEG), decrease the surface coverage, and increase the density of electron trap states, impacting the recombination dynamics at the ns timescale. The amines in poly(ethylene imine) (PEI) on the other hand can saturate and remove surface traps to a wide extent. Implications for catalysis are discussed. Full article
(This article belongs to the Special Issue Photo-Induced Electron Transfer Kinetics in Catalysis)
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19 pages, 6569 KiB  
Article
Picosecond Lifetime Hot Electrons in TiO2 Nanoparticles for High Catalytic Activity
by Bochao Li, Hao Li, Chang Yang, Boyu Ji, Jingquan Lin and Toshihisa Tomie
Catalysts 2020, 10(8), 916; https://doi.org/10.3390/catal10080916 - 10 Aug 2020
Cited by 4 | Viewed by 2651
Abstract
A large number of studies have examined the origins of high-catalytic activities of nanoparticles, but very few have discussed the lifetime of high-energy electrons in nanoparticles. The lifetime is one of the factors determining electron transfer and thus catalytic activity. Much of the [...] Read more.
A large number of studies have examined the origins of high-catalytic activities of nanoparticles, but very few have discussed the lifetime of high-energy electrons in nanoparticles. The lifetime is one of the factors determining electron transfer and thus catalytic activity. Much of the lifetime of electrons reported in the literature is too short for a high transfer-efficiency of photo-excited electrons from a catalyst to the attached molecules. We observed TiO2 nanoparticles using the femtosecond laser two-color pump-probe technique with photoemission electron microscopy having a 40 nm spatial resolution. A lifetime longer than 4 ps was observed together with a fast decay component of 100 fs time constant when excited by a 760 nm laser. The slow decay component was observed only when the electrons in an intermediate state pumped by the fundamental laser pulse were excited by the second harmonic pulse. The electronic structure for the asymmetry of the pump-probe signal and the origin of the two decay components are discussed based on the color center model of the oxygen vacancy. Full article
(This article belongs to the Special Issue Photo-Induced Electron Transfer Kinetics in Catalysis)
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18 pages, 815 KiB  
Article
Asymmetry in Charge Transfer Pathways Caused by Pigment–Protein Interactions in the Photosystem II Reaction Center Complex
by Yoshihiro Sato and Danielle Sicotte
Catalysts 2020, 10(6), 718; https://doi.org/10.3390/catal10060718 - 26 Jun 2020
Viewed by 2326
Abstract
This article discusses the photoinduced charge transfer (CT) kinetics within the reaction center complex of photosystem II (PSII RC). The PSII RC exhibits a structural symmetry in its arrangement of pigments forming two prominent branches, D1 and D2. Despite this symmetry, the CT [...] Read more.
This article discusses the photoinduced charge transfer (CT) kinetics within the reaction center complex of photosystem II (PSII RC). The PSII RC exhibits a structural symmetry in its arrangement of pigments forming two prominent branches, D1 and D2. Despite this symmetry, the CT has been observed to occur exclusively in the D1 branch. The mechanism to realize such functional asymmetry is yet to be understood. To approach this matter, we applied the theoretical tight-binding model of pigment excitations and simulated CT dynamics based upon the framework of an open quantum system. This simulation used a recently developed method of computation based on the quasi-adiabatic propagator path integral. A quantum CT state is found to be dynamically active when its site energy is resonant with the exciton energies of the PSII RC, regardless of the excitonic landscape we utilized. Through our investigation, it was found that the relative displacement between the local molecular energy levels of pigments can play a crucial role in realizing this resonance and therefore greatly affects the CT asymmetry in the PSII RC. Using this mechanism phenomenologically, we demonstrate that a near 100-to-1 ratio of reduction between the pheophytins in the D1 and D2 branches can be realized at both 77 K and 300 K. Our results indicate that the chlorophyll Chl D 1 is the most active precursor of the primary charge separation in the D1 branch and that the reduction of the pheophytins can occur within pico-seconds. Additionally, a broad resonance of the active CT state implies that a large static disorder observed in the CT state originates in the fluctuations of the relative displacements between the local molecular energy levels of the pigments in the PSII RC. Full article
(This article belongs to the Special Issue Photo-Induced Electron Transfer Kinetics in Catalysis)
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