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Publications (10 of 14) Show all publications
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
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)2-s2.0-85041107994 (Scopus ID)
Note

QC 20180206

Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-02-06Bibliographically 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
Daniel, Q., Duan, L., Timmer, B. J. J., Chen, H., Luo, X., Ambre, R., . . . Sun, L. (2018). Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst. ACS Catalysis, 8(5), 4375-4382
Open this publication in new window or tab >>Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst
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2018 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 5, p. 4375-4382Article in journal (Refereed) Published
Abstract [en]

The mononuclear ruthenium complex [Ru(pdc)L-3] (H(2)pdc = 2,6-pyridinedicarboxylic acid, L = N-heterocycles such as 4-picoline) has previously shown promising catalytic efficiency toward water oxidation, both in homogeneous solutions and anchored on electrode surfaces. However, the detailed water oxidation mechanism catalyzed by this type of complex has remained unclear. In order to deepen understanding of this type of catalyst, in the present study, [Ru(pdc)(py)(3)] (py = pyridine) has been synthesized, and the detailed catalytic mechanism has been studied by electrochemistry, UV-vis, NMR, MS, and X-ray crystallography. Interestingly, it was found that once having reached the Ru-IV state, this complex promptly formed a stable ruthenium dimer [Ru-III(pdc)(py)(2)-O-Ru-IV(pdc)(py)(2)](+). Further investigations suggested that the present dimer, after one pyridine ligand exchange with water to form [Ru-III(pdc)(py)(2)-O-Ru-IV(pdc)(py)(H2O)](+), was the true active species to catalyze water oxidation in homogeneous solutions.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
Keywords
solar fuels, water oxidation, electrochemistry, ruthenium dimer, mechanism of O-O bond formation
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-231630 (URN)10.1021/acscatal.7b03768 (DOI)000431727300070 ()2-s2.0-85046695744 (Scopus ID)
Note

QC 20180702

Available from: 2018-07-02 Created: 2018-07-02 Last updated: 2018-07-02Bibliographically approved
Zhang, B. & Sun, L. (2018). Why nature chose the Mn4CaO5 cluster as water-splitting catalyst in photosystem II: a new hypothesis for the mechanism of O-O bond formation. Dalton Transactions, 47(41), 14381-14387
Open this publication in new window or tab >>Why nature chose the Mn4CaO5 cluster as water-splitting catalyst in photosystem II: a new hypothesis for the mechanism of O-O bond formation
2018 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 47, no 41, p. 14381-14387Article, review/survey (Refereed) Published
Abstract [en]

Resolving the questions, namely, the selection of Mn by nature to build the oxygen-evolving complex (OEC) and the presence of a cubic Mn3CaO4 structure in OEC coupled with an additional dangling Mn (Mn4) via mu-O atom are not only important to uncover the secret of water oxidation in nature, but also essential to achieve a blueprint for developing advanced water-oxidation catalysts for artificial photosynthesis. Based on the important experimental results reported so far in the literature and on our own findings, we propose a new hypothesis for the water oxidation mechanism in OEC. In this new hypothesis, we propose for the first time, a complete catalytic cycle involving a charge-rearrangement-induced Mn-VII-dioxo species on the dangling Mn4 during the S-3 -> S-4 transition. Moreover, the O-O bond is formed within this Mn-VII-dioxo site, which is totally different from that discussed in other existing proposals.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-241340 (URN)10.1039/c8dt01931b (DOI)000454842000001 ()30129959 (PubMedID)2-s2.0-85055182383 (Scopus ID)
Note

QC 20190121

Available from: 2019-01-21 Created: 2019-01-21 Last updated: 2019-01-21Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4093-1251

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