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Special Issue "Advances in Molecular Artificial Photosynthesis"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "B1: Solar Energy and Photovoltaic Systems".

Deadline for manuscript submissions: closed (31 December 2021).

Special Issue Editor

Dr. Julien Warnan
E-Mail Website
Guest Editor
Department of Chemistry, Technical University of Munich, 85747 Garching, Germany
Interests: energy storage; solar energy conversion; (photo)(electro)catalysis; artificial photosynthesis; hybrid materials; organic dyes; molecular catalysts; polymers; MOFs

Special Issue Information

Dear Colleagues,

I would like to invite contributions from all researchers who would like to submit their research articles to the Special Issue of Energies (ISSN 1996-1073; CODEN: ENERGA) on "Advances in Molecular Artificial Photosynthesis".

Solar fuel production enables the vision of sustainable preparation of chemical energy carriers with long-term storage capacity to be realised. Such processes, collectively referred to as artificial photosynthesis, synergistically harness the powers of biological, organic, and material systems to develop a broad range of synthetic systems and create a platform for the fundamental study of interfacial electron transfers and catalytic mechanisms. This topical issue will be dedicated to the recent advances in a very broad and exciting field of research with a specific glance towards molecule-integrating systems related to the (photo)production of chemicals from abundant sources (CO2, biomass, water, N2, and so forth). This should take the form of experimental and/or computational research articles and combinations thereof, as well as short specific reviews and perspectives. The main criteria for paper acceptance will be rigorous academic excellence, originality and novelty of systems, methods or fundamental findings. Overall, I anticipate a broad readership of this multidisciplinary research from relevant disciplines, including but not limited to: molecular oxidative and reductive catalysis, (bio)hybrid materials, photochemistry, electrochemistry, synthesis (organic, inorganic, supramolecular) and spectroscopies.

Dr. Julien Warnan
Guest Editor

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 papers will be 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. Energies is an international peer-reviewed open access semimonthly 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 2200 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

  • artificial photosynthesis
  • molecular systems
  • electrochemistry
  • photochemistry
  • colloids
  • electrode functionalisation

Published Papers (3 papers)

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Research

Article
FeI Intermediates in N2O2 Schiff Base Complexes: Effect of Electronic Character of the Ligand and of the Proton Donor on the Reactivity with Carbon Dioxide
Energies 2021, 14(18), 5723; https://doi.org/10.3390/en14185723 - 11 Sep 2021
Viewed by 555
Abstract
The characterization of competent intermediates of metal complexes, involved in catalytic transformations for the activation of small molecules, is an important target for mechanistic comprehension and catalyst design. Iron complexes deserve particular attention, due to the rich chemistry of iron that allows their [...] Read more.
The characterization of competent intermediates of metal complexes, involved in catalytic transformations for the activation of small molecules, is an important target for mechanistic comprehension and catalyst design. Iron complexes deserve particular attention, due to the rich chemistry of iron that allows their application both in oxidation and reduction processes. In particular, iron complexes with tetradentate Schiff base ligands show the possibility to electrochemically generate FeI intermediates, capable of reacting with carbon dioxide. In this work, we investigate the electronic and spectroscopic features of FeI intermediates in five Fe(LN2O2) complexes, and evaluate the electrocatalytic reduction of CO2 in the presence of phenol (PhOH) or trifluoroethanol (TFE) as proton donors. The main findings include: (i) a correlation of the potentials of the FeII/I couples with the electronic character of the LN2O2 ligand and the energy of the metal-to-ligand charge transfer absorption of FeI species (determined by spectroelectrochemistry, SEC-UV/Vis); (ii) the reactivity of FeI species with CO2, as proven by cyclic voltammetry and SEC-UV/Vis; (iii) the identification of Fe(salen) as a competent homogeneous electrocatalyst for CO2 reduction to CO, in the presence of phenol or trifluoroethanol proton donors (an overpotential of 0.91 V, a catalytic rate constant estimated at 5 × 104 s−1, and a turnover number of 4); and (iv) the identification of sudden, ligand-assisted decomposition routes for complexes bearing a ketylacetoneimine pendant, likely associated with the protonation under cathodic conditions of the ligands. Full article
(This article belongs to the Special Issue Advances in Molecular Artificial Photosynthesis)
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Article
Molecular Dye-Sensitized Photocatalysis with Metal-Organic Framework and Metal Oxide Colloids for Fuel Production
Energies 2021, 14(14), 4260; https://doi.org/10.3390/en14144260 - 14 Jul 2021
Viewed by 662
Abstract
Colloidal dye-sensitized photocatalysis is a promising route toward efficient solar fuel production by merging properties of catalysis, support, light absorption, and electron mediation in one. Metal-organic frameworks (MOFs) are host materials with modular building principles allowing scaffold property tailoring. Herein, we combine these [...] Read more.
Colloidal dye-sensitized photocatalysis is a promising route toward efficient solar fuel production by merging properties of catalysis, support, light absorption, and electron mediation in one. Metal-organic frameworks (MOFs) are host materials with modular building principles allowing scaffold property tailoring. Herein, we combine these two fields and compare porous Zr-based MOFs UiO-66-NH2(Zr) and UiO-66(Zr) to monoclinic ZrO2 as model colloid hosts with co-immobilized molecular carbon dioxide reduction photocatalyst fac-ReBr(CO)3(4,4′-dcbpy) (dcbpy = dicarboxy-2,2′-bipyridine) and photosensitizer Ru(bpy)2(5,5′-dcbpy)Cl2 (bpy = 2,2′-bipyridine). These host-guest systems demonstrate selective CO2-to-CO reduction in acetonitrile in presence of an electron donor under visible light irradiation, with turnover numbers (TONs) increasing from ZrO2, to UiO-66, and to UiO-66-NH2 in turn. This is attributed to MOF hosts facilitating electron hopping and enhanced CO2 uptake due to their innate porosity. Both of these phenomena are pronounced for UiO-66-NH2(Zr), yielding TONs of 450 which are 2.5 times higher than under MOF-free homogeneous conditions, highlighting synergistic effects between supramolecular photosystem components in dye-sensitized MOFs. Full article
(This article belongs to the Special Issue Advances in Molecular Artificial Photosynthesis)
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Article
Two Excited State Collaboration of Heteroleptic Ir(III)-Coumarin Complexes for H2 Evolution Dye-Sensitized Photocatalysts
Energies 2021, 14(9), 2425; https://doi.org/10.3390/en14092425 - 24 Apr 2021
Cited by 1 | Viewed by 703
Abstract
Interfacial electron injection from a photoexcited surface-immobilized dye to a semiconductor substrate is a key reaction for dye-sensitized photocatalysts. We previously reported that the molecular orientation of heteroleptic Ir(III) photosensitizer on the TiO2 nanoparticle surface was important for efficient interfacial electron injection. [...] Read more.
Interfacial electron injection from a photoexcited surface-immobilized dye to a semiconductor substrate is a key reaction for dye-sensitized photocatalysts. We previously reported that the molecular orientation of heteroleptic Ir(III) photosensitizer on the TiO2 nanoparticle surface was important for efficient interfacial electron injection. In this work, to overcome the weak light absorption ability of heteroleptic Ir(III) photosensitizer and to improve the photoinduced charge-separation efficiency at the dye–semiconductor interface, we synthesized two heteroleptic Ir(III) complexes with different coumarin dyes, [Ir(C6)2(H4CPbpy)]Cl and [Ir(C30)2(H4CPbpy)]Cl [Ir-CX; X = 6 or 30; HC6 = 3-(2-enzothiazolyl)-7-(diethylamino)coumarin, HC30 = 3-(2-N-methylbenzimidazolyl)-7-N,N-diethylaminocoumarin, H4CPbpy = 4,4′-bis(methylphosphonic acid)-2,2′-bipyridine], as the cyclometalated ligands and immobilized them on the surface of Pt-cocatalyst-loaded TiO2 nanoparticles. Ultraviolet-visible absorption and emission spectroscopy revealed that the singlet ligand-centered (1LC) absorption and triplet 3LC emission bands of Ir-C30 occurred at shorter wavelengths than those of Ir-C6, while time-dependent density-functional-theory data suggested that the ligand-to-ligand charge transfer (LLCT) excited states of the two complexes were comparable. The photocatalytic H2 evolution activity of the Ir-C6-sensitized Pt-TiO2 nanoparticles ([email protected]2) under visible light irradiation (λ > 420 nm) was higher than that of [email protected]2. In contrast, their activities were comparable under irradiation with monochromatic light (λ = 450 ± 10 nm), which is absorbed comparably by both Ir-CX complexes. These results suggest that the internal conversion from the higher-lying LC state to the LLCT state effectively occurs in both Ir-CX complexes to trigger electron injection to TiO2. Full article
(This article belongs to the Special Issue Advances in Molecular Artificial Photosynthesis)
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