Homogeneous Photocatalytic H2 Production Using a RuII

Bathophenanthroline Metal-to-Ligand Charge-TransferPhotosensitizer

What was the inspiration for this cover design?Water splitting photocatalysis is a light-driven process aimed at theformation of hydrogen and oxygen gas from water. Hydrogen isa high energy feedstock chemical and it is considered an attractiveform of renewables. This cover highlights the major steps involvedin homogeneous hydrogen production from water, important forrevealing mechanistic details ultimately leading to new and im-proved photocatalytic materials and systems. For the successfuloptimization of this reduction half-reaction, water oxidation was re-placed using a sacrificial electron donation pathway. The processinitiates with the absorption of photons by a ruthenium(II) tris-bathophenanthroline photosensitizer forming an excited statewhich receives an electron from the N,N-dimethyl-p-toluidine(DMT) electron donor. Subsequently, the reduced photosensitizertransfers an electron to a molecular cobalt-based water reductioncatalyst. For each molecule of hydrogen evolved, two electronsand two aqueous protons are required in the process.

What are the most significant results of this study?We describe in detail a new &composite for&homogeneous hy-drogen production. A ruthenium(II) tris-bathophenanthroline pho-tosensitizer was found to impart greater operational stability withrespect to the prototypical ruthenium(II) tris-bipyridine sensitizer.In addition, the electron donor (DMT) enhanced the longevity ofthe system owing to the lack of formation of high-energy radicalsthat typically result from the oxidation of related amines used assacrificial electron donors. Moreover, the multi-step electron trans-fer mechanism was probed by transient absorption and photolumi-nescence spectroscopy to extract critical kinetic rate parameters.Our findings can lead to further advancements in the field of watersplitting photocatalysis, particular in the associated measurementscience.

What topics are you working on at the moment?Prof. Khnayzer: Major research includes the photophysics and pho-tochemistry of transition-metal complexes for utilization in homo-geneous and heterogeneous solar hydrogen generation, design ofsensors, and photodynamic therapy of cancer.Prof. Castellano: Current research focuses on metal–organic chro-mophore photophysics and energy transfer, photochemical upcon-

version phenomena, solar fuels photocatalysis, energy transductionat semiconductor/molecular interfaces, transient bond formingphotoreactions, and excited state electron transfer processes.

AcknowledgementsR.S.K. acknowledges funds from the School Research and Develop-ment Council at LAU (SRDC-t2014-02) and the Lebanese NationalCouncil for Scientific Research (Ref: 05-06-14). F.N.C. acknowledgessupport from the National Science Foundation (CHE-1465058).K.A.E. is a Chemistry Graduate Scholars Research Fellow at NCState.

Invited for this month’s cover are the research groups of Prof. Rony S. Khnayzer at Lebanese American University and Prof.Felix (Phil) N. Castellano at North Carolina State University. The cover picture illustrates the absorption of visible light bya ruthenium bathophenanthroline MLCT chromophore followed by a sequence of electron transfer steps that ultimatelyleads to the efficient production of hydrogen gas from water. Read the full text of the article at 10.1002/cplu.201600227.

Babatunde S. Olaiya Felix N. Castellano Karim + A. El Roz Rony S. Khnayzer

ChemPlusChem 2016, 81, 1 – 2 � 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim1

These are not the final page numbers! ��These are not the final page numbers! ��

Cover ProfileDOI: 10.1002/cplu.201600424

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COVER PROFILE

R. S. Khnayzer,* B. S. Olaiya, K. A. El Roz,F. N. Castellano*

&& –&&

Homogeneous Photocatalytic H2

Production Using a RuII

Bathophenanthroline Metal-to-LigandCharge-Transfer Photosensitizer

“…Our findings can lead to further ad-vancements in the field of water split-ting photocatalysis, particular in the as-sociated measurement science….”Read more about the story behind the

cover in the Cover Profile and about theresearch itself (DOI: 10.1002/cplu.201600227).

Ru bathophenanthroline #photosensitizer to enhance photocatalytic H2 production by Khnayzer (@LebAmU-niv), Castellano (@NCState) SPACE RESERVED FOR IMAGE AND LINK

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Please check that the ORCID identifiers listed below are correct. We encourage all authors to provide an ORCID identifierfor each coauthor. ORCID is a registry that provides researchers with a unique digital identifier. Some funding agenciesrecommend or even require the inclusion of ORCID IDs in all published articles, and authors should consult their fundingagency guidelines for details. Registration is easy and free; for further information, see http://orcid.org/.

Prof. Rony S. Khnayzer http://orcid.org/0000-0001-7775-0027Babatunde S. OlaiyaKarim A. El RozProf. Felix N. Castellano http://orcid.org/0000-0001-7546-8618

ChemPlusChem 2016, 81, 1 – 2 www.chempluschem.org � 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim2

�� These are not the final page numbers!�� These are not the final page numbers!

1 12 23 34 45 56 67 78 89 9

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