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Publications (10 of 16) Show all publications
Zhang, B. & Sun, L. (2019). Across the Board: Licheng Sun on the Mechanism of O-O Bond Formation in Photosystem II. ChemSusChem, 12(14), 3401-3404
Open this publication in new window or tab >>Across the Board: Licheng Sun on the Mechanism of O-O Bond Formation in Photosystem II
2019 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 12, no 14, p. 3401-3404Article in journal (Refereed) Published
Abstract [en]

In this series of articles, the board members of ChemSusChem discuss recent research articles that they consider of exceptional quality and importance for sustainability. This entry features Prof. L. Sun, who proposes a special mechanism for O-O bond formation in photosystem II with involvement of an Mn-VII-oxo species induced by charge- and structural rearrangements. In this viewpoint, Proton transfer is involved in changes of the first coordination spheres around the Mn-VII-oxo site on the dangling Mn4 with de- and re-coordination of carboxylates (Glu333 and Asp170).

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
disproportionation, oxygen evolution, photosystem II, structural rearrangement, water splitting
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-257575 (URN)10.1002/cssc.201901438 (DOI)000478633900023 ()31240851 (PubMedID)2-s2.0-85068351514 (Scopus ID)
Note

QC 20190923

Available from: 2019-09-23 Created: 2019-09-23 Last updated: 2019-09-23Bibliographically approved
Zhang, B. & Sun, L. (2019). Artificial photosynthesis: opportunities and challenges of molecular catalysts. Chemical Society Reviews, 48(7), 2216-2264
Open this publication in new window or tab >>Artificial photosynthesis: opportunities and challenges of molecular catalysts
2019 (English)In: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 48, no 7, p. 2216-2264Article, review/survey (Refereed) Published
Abstract [en]

Molecular catalysis plays an essential role in both natural and artificial photosynthesis (AP). However, the field of molecular catalysis for AP has gradually declined in recent years because of doubt about the long-term stability of molecular-catalyst-based devices. This review summarizes the development history of molecular-catalyst-based AP, including the fundamentals of AP, molecular catalysts for water oxidation, proton reduction and CO2 reduction, and molecular-catalyst-based AP devices, and it provides an analysis of the advantages, challenges, and stability of molecular catalysts. With this review, we aim to highlight the following points: (i) an investigation on molecular catalysis is one of the most promising ways to obtain atom-efficient catalysts with outstanding intrinsic activities; (ii) effective heterogenization of molecular catalysts is currently the primary challenge for the application of molecular catalysis in AP devices; (iii) development of molecular catalysts is a promising way to solve the problems of catalysis involved in practical solar fuel production. In molecular-catalysis-based AP, much has been attained, but more challenges remain with regard to long-term stability and heterogenization techniques.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-251498 (URN)10.1039/c8cs00897c (DOI)000464383500009 ()30895997 (PubMedID)2-s2.0-85063728666 (Scopus ID)
Note

QC 20190516

Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-16Bibliographically approved
Cuartero, M., Chai, L., Zhang, B., De Marco, R. & Crespo, G. A. (2019). Ferrocene self assembled monolayer as a redox mediator for triggering ion transfer across nanometer-sized membranes. Electrochimica Acta, 315, 84-93
Open this publication in new window or tab >>Ferrocene self assembled monolayer as a redox mediator for triggering ion transfer across nanometer-sized membranes
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2019 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 315, p. 84-93Article in journal (Refereed) Published
Abstract [en]

Modulation of ion-transfer processes across nanometer-sized voltammetry membranes by ferrocene-based self-assembled monolayer on regular glassy carbon electrode is herein demonstrated. The composition of the membrane is advantageously tuned to promote either cation or anion transfer: the presence of an exchangeable cation results in cation transfer, whereas a lipophilic salt induces anion transfer through the fulfilment of the electroneutrality of the system. When an anodic scan oxidizes ferrocene moieties in the monolayer, these are stabilized by the pairing of lipophilic anions present in the membrane. As a result, either, hydrophilic cations present in the membrane are expelled into the solution or anions enter from the solution generating hence reversible and voltammetric waves for these transfers. The use of a redox active monolayer rather than a conducting polymer film or a redox active compound into the membrane overcomes a number of drawbacks previously manifested by these systems. The confinement of the redox process in a thin film at the immediate vicinity of the membrane allows to avoid the need of elevated number of redox moieties to be sued in the membrane, therefore suppressing its acute leaching and being compatible with the incorporation of both cation and anion ionophores for the first time. In this sense, assisted transfer of lithium and chloride are shown as proof-of-concept. Here, the peak potential of the associated voltammetric waves shifts according to the Nernst equation, in analogy to potentiometric sensors. Analytical detection of lithium and chloride ions in real samples is additionally presented.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Voltammetry membranes, Self-assembled monolayer, Ion transfer, Ionophores
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-254066 (URN)10.1016/j.electacta.2019.05.091 (DOI)000470108800011 ()2-s2.0-85066091769 (Scopus ID)
Note

QC 20190624

Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-06-24Bibliographically approved
Liu, T., Zhang, B. & Sun, L. (2019). Iron-Based Molecular Water Oxidation Catalysts: Abundant, Cheap, and Promising. Chemistry - An Asian Journal, 14(1), 31-43
Open this publication in new window or tab >>Iron-Based Molecular Water Oxidation Catalysts: Abundant, Cheap, and Promising
2019 (English)In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 14, no 1, p. 31-43Article, review/survey (Refereed) Published
Abstract [en]

An efficient and robust water oxidation catalyst based on abundant and cheap materials is the key to converting solar energy into fuels through artificial photosynthesis for the future of humans. The development of molecular water oxidation catalysts (MWOCs) is a smart way to achieve promising catalytic activity, thanks to the clear structures and catalytic mechanisms of molecular catalysts. Efficient MWOCs based on noble-metal complexes, for example, ruthenium and iridium, have been well developed over the last 30 years; however, the development of earth-abundant metal-based MWOCs is very limited and still challenging. Herein, the promising prospect of iron-based MWOCs is highlighted, with a comprehensive summary of previously reported studies and future research focus in this area.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
artificial photosynthesis, electrochemistry, iron, molecular catalysts, oxidation, water splitting
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-241314 (URN)10.1002/asia.201801253 (DOI)000454953700003 ()30362258 (PubMedID)2-s2.0-85057257052 (Scopus ID)
Note

QC 20190125

Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-01-25Bibliographically approved
Zhang, P., Sheng, X., Chen, X., Fang, Z., Jiang, J., Wang, M., . . . Sun, L. (2019). Paired Electrocatalytic Oxygenation and Hydrogenation of Organic Substrates with Water as the Oxygen and Hydrogen Source. Angewandte Chemie International Edition, 58(27), 9155-9159
Open this publication in new window or tab >>Paired Electrocatalytic Oxygenation and Hydrogenation of Organic Substrates with Water as the Oxygen and Hydrogen Source
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2019 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 58, no 27, p. 9155-9159Article in journal (Refereed) Published
Abstract [en]

The use of water as an oxygen and hydrogen source for the paired oxygenation and hydrogenation of organic substrates to produce valuable chemicals is of utmost importance as a means of establishing green chemical syntheses. Inspired by the active Ni3+ intermediates involved in electro-catalytic water oxidation by nickel-based materials, we prepared NiBx as a catalyst and used water as the oxygen source for the oxygenation of various organic compounds. NiBx was further employed as both an anode and a cathode in a paired electrosynthesis cell for the respective oxygenation and hydrogenation of organic compounds, with water as both the oxygen and hydrogen source. Conversion efficiency and selectivity of >= 99% were observed during the oxygenation of 5-hydroxy-methylfurfural to 2,5-furandicarboxylic acid and the simultaneous hydrogenation of p-nitrophenol to p-aminophenol. This paired electrosynthesis cell has also been coupled to a solar cell as a stand-alone reactor in response to sunlight.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2019
Keywords
electrochemistry, green chemical synthesis, hydrogenation, oxygenation, water
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-255764 (URN)10.1002/anie.201903936 (DOI)000476691200033 ()31025774 (PubMedID)2-s2.0-85066906976 (Scopus ID)
Note

QC 20190816

Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Zhang, B. & Sun, L. (2019). Ru-bda: Unique Molecular Water-Oxidation Catalysts with Distortion Induced Open Site and Negatively Charged Ligands. Journal of the American Chemical Society, 141(14), 5565-5580
Open this publication in new window or tab >>Ru-bda: Unique Molecular Water-Oxidation Catalysts with Distortion Induced Open Site and Negatively Charged Ligands
2019 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 141, no 14, p. 5565-5580Article, review/survey (Refereed) Published
Abstract [en]

A water-oxidation catalyst with high intrinsic activity is the foundation for developing any type of water-splitting device. To celebrate its 10 years anniversary, in this Perspective we focus on the state-of-the-art molecular water-oxidation catalysts (MWOCs), the Ru-bda series (bda = 2,2'-bipyridine-6,6'-dicarboxylate), to offer strategies for the design and synthesis of more advanced MWOCs. The O-O bond formation mechanisms, derivatives, applications, and reasons behind the outstanding catalytic activities of Ru-bda catalysts are summarized and discussed. The excellent performance of the Ru-bda catalyst is owing to its unique structural features: the distortion induced 7-coordination and the carboxylate ligands with coordination flexibility, proton transfer function as well as small steric hindrance. Inspired by the Ru-bda catalysts, we emphasize that the introduction of negatively charged groups, such as the carboxylate group, into ligands is an effective strategy to lower the onset potential of MWOCs. Moreover, distortion of the regular configuration of a transition metal complex by ligand design to generate a wide open site as the catalytic site for binding the substrate as an extra-coordination is proposed as a new concept for the design of efficient molecular catalysts. These inspirations can be expected to play a great role in not only water oxidation catalysis but also other small molecule activation and conversion reactions involving artificial photosynthesis, such as CO2 reduction and N-2 fixation reactions.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-251494 (URN)10.1021/jacs.8b12862 (DOI)000464769000001 ()30889353 (PubMedID)2-s2.0-85064226482 (Scopus ID)
Note

QC 20190516

Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-16Bibliographically approved
Zhang, W., Hua, Y., Wang, L., Zhang, B., Li, Y., Liu, P., . . . Kloo, L. (2019). The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells. ACS APPLIED ENERGY MATERIALS, 2(9), 6768-6779
Open this publication in new window or tab >>The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells
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2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 9, p. 6768-6779Article in journal (Refereed) Published
Abstract [en]

Two zinc-based coordination complexes Y3 and Y4 have been synthesized and characterized, and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) has been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a disconnected porphyrin ring. On the other hand, Y4 consists of a porphyrin core and therefore is a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD-based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 is analyzed and can be attributed to the difference in packing of the nonplanar and planar building blocks in the corresponding materials.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
ligand conjugation, coordination complex, porphyrin, hole-transport material, perovskite
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-261967 (URN)10.1021/acsaem.9b01223 (DOI)000487770000073 ()
Note

QC 20191014

Available from: 2019-10-14 Created: 2019-10-14 Last updated: 2019-10-14Bibliographically approved
Fan, L., Zhang, P., Zhang, B., Daniel, Q., Timmer, B., Zhang, F. & Sun, L. (2018). 3D Core-Shell NiFeCr Catalyst on a Cu Nanoarray for Water Oxidation: Synergy between Structural and Electronic Modulation. ACS ENERGY LETTERS, 3(12), 2865-2874
Open this publication in new window or tab >>3D Core-Shell NiFeCr Catalyst on a Cu Nanoarray for Water Oxidation: Synergy between Structural and Electronic Modulation
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2018 (English)In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 3, no 12, p. 2865-2874Article in journal (Refereed) Published
Abstract [en]

Low cost transition metal-based electrocatalysts for water oxidation and understanding their structure-activity relationship are greatly desired for clean and sustainable chemical fuel production. Herein, a core-shell (CS) NiFeCr metal/metal hydroxide catalyst was fabricated on a 3D Cu nanoarray by a simple electrodeposition-activation method. A synergistic promotion effect between electronic structure modulation and nanostructure regulation was presented on a CS-NiFeCr oxygen evolution reaction (OER) catalyst: the 3D nanoarchitecture facilitates the mass transport process, the in situ formed interface metal/metal hydroxide heterojunction accelerates the electron transfer, and the electronic structure modulation by Cr incorporation improves the reaction kinetics. Benefiting from the synergy between structural and electronic modulation, the catalyst shows excellent activity toward water oxidation under alkaline conditions: overpotential of 200 mV at 10 mA/cm(2) current density and Tafel slope of 28 mV/dec. This work opens up a new window for understanding the structure-activity relationship of OER catalysts and encourages new strategies for development of more advanced OER catalysts.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-241005 (URN)10.1021/acsenergylett.8b01897 (DOI)000453805100003 ()2-s2.0-85056263175 (Scopus ID)
Note

QC 20190109

Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-08-20Bibliographically approved
Zhang, P., Li, L., Nordlund, D., Chen, H., Fan, L., Zhang, B., . . . Sun, L. (2018). Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation. Nature Communications, 9(1), Article ID 381.
Open this publication in new window or tab >>Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation
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2018 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, no 1, article id 381Article in journal (Refereed) Published
Abstract [en]

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm-2. The core-shell NiFeCu electrode exhibits pH-dependent oxygen evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-222290 (URN)10.1038/s41467-017-02429-9 (DOI)000423430900001 ()2-s2.0-85041107994 (Scopus ID)
Note

QC 20180206

Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2019-09-18Bibliographically approved
Wang, L., Zhang, J., Liu, P., Xu, B., Zhang, B., Chen, H., . . . Sun, L. (2018). Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells. Chemical Communications, 54(69)
Open this publication in new window or tab >>Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells
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2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 69Article in journal (Refereed) Published
Abstract [en]

Two novel dopant-free hole-transport materials (HTMs) with spiro[dibenzo[c,h]xanthene-7,9-fluorene] (SDBXF) skeletons were prepared via facile synthesis routes. A power conversion efficiency of 15.9% in perovskite solar cells is attained by using one HTM without dopants, which is much higher than undoped Spiro-OMeTAD-based devices (10.8%). The crystal structures of both new HTMs were systematically investigated to reveal the reasons behind such differences in performance and to indicate the design principles of more advanced HTMs.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:kth:diva-234569 (URN)10.1039/c8cc04026e (DOI)000442605100002 ()30043013 (PubMedID)2-s2.0-85052539543 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180917

Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2019-08-20Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4093-1251

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