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Ye, L., Gao, Y., Cao, S., Chen, H., Yao, Y., Hou, J. & Sun, L. (2018). Assembly of highly efficient photocatalytic CO2 conversion systems with ultrathin two-dimensional metal-organic framework nanosheets. Applied Catalysis B: Environmental, 227, 54-60
Open this publication in new window or tab >>Assembly of highly efficient photocatalytic CO2 conversion systems with ultrathin two-dimensional metal-organic framework nanosheets
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2018 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 227, p. 54-60Article in journal (Refereed) Published
Abstract [en]

An ultrathin two-dimensional Zn porphyrin-based metal-organic framework (Zn-MOF nanosheets) is developed and used for the first time in photoreduction of CO2 to CO. Consequently, two novelty noble-metal-free hybrid photocatalytic systems are established and displayed outstanding photocatalytic activity and selectivity for CO evolution under mild photocatalytic reaction conditions. The insight revealed Zn-MOF nanosheets as photo sensitizer displays a better charge transport ability and longer lifetime of the photogenerated electron-hole pairs than the Zn-MOF bulk, which are confirmed by photoelectrochemical impedance and photoluminescence (PL) measurements. These studies show that the development of noble-metal-free photocatalytic systems and various MOF-based materials for photocatalytic applications are promising.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
CO2 reduction, Photocatalysis, Metal-organic frameworks, Nanosheets, Zn porphyrin
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-226178 (URN)10.1016/j.apcatb.2018.01.028 (DOI)000428491000006 ()2-s2.0-85042913816 (Scopus ID)
Note

QC 20180516

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-05-16Bibliographically approved
Hou, J., Cao, S., Sun, Y., Wu, Y., Liang, F., Lin, Z. & Sun, L. (2018). Atomically Thin Mesoporous In2O3-x/In2S3 Lateral Heterostructures Enabling Robust Broadband-Light Photo-Electrochemical Water Splitting. Advanced Energy Materials, 8(9), Article ID 1701114.
Open this publication in new window or tab >>Atomically Thin Mesoporous In2O3-x/In2S3 Lateral Heterostructures Enabling Robust Broadband-Light Photo-Electrochemical Water Splitting
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2018 (English)In: Advanced Energy Materials, ISSN 1614-6832, Vol. 8, no 9, article id 1701114Article in journal (Refereed) Published
Abstract [en]

Atomically thin 2D heterostructures have opened new realms in electronic and optoelectronic devices. Herein, 2D lateral heterostructures of mesoporous In2O3-x/In2S3 atomic layers are synthesized through the in situ oxidation of In2S3 atomic layers by an oxygen plasma-induced strategy. Based on experimental observations and theoretical calculations, the prolonged charge carrier lifetime and increased electron density reveal the efficient photoexcited carrier transport and separation in the In2O3-x/In2S3 layers by interfacial bonding at the atomic level. As expected, the synergistic structural and electronic modulations of the In2O3-x/In2S3 layers generate a photocurrent of 1.28 mA cm(-2) at 1.23 V versus a reversible hydrogen electrode, nearly 21 and 79 times higher than those of the In2S3 atomic layers and bulk counterpart, respectively. Due to the large surface area, abundant active sites, broadband-light harvesting ability, and effective charge transport pathways, the In2O3-x/In2S3 layers build efficient pathways for photoexcited charge in the 2D semiconductive channels, expediting charge transport and kinetic processes and enhancing the robust broadband-light photo-electrochemical water splitting performance. This work paves new avenues for the exploration and design of atomically thin 2D lateral heterostructures toward robust photo-electrochemical applications and solar energy utilization.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
atomically thin layers, charge separation, In2O3-x/In2S3, lateral heterostructures, photo-electrochemical water splitting
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-226792 (URN)10.1002/aenm.201701114 (DOI)000429318400001 ()
Note

QC 20180521

Available from: 2018-05-21 Created: 2018-05-21 Last updated: 2018-05-21Bibliographically approved
Hua, Y., Liu, P., Li, Y., Sun, L. & Kloo, L. (2018). Composite Hole-Transport Materials Based on a Metal-Organic Copper Complex and Spiro-OMeTAD for Efficient Perovskite Solar Cells. SOLAR RRL, 2(5), Article ID UNSP 1700073.
Open this publication in new window or tab >>Composite Hole-Transport Materials Based on a Metal-Organic Copper Complex and Spiro-OMeTAD for Efficient Perovskite Solar Cells
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2018 (English)In: SOLAR RRL, ISSN 2367-198X, Vol. 2, no 5, article id UNSP 1700073Article in journal (Refereed) Published
Abstract [en]

Spiro-OMeTAD has been the most commonly used hole-transport material in perovskite solar cells. However, this material shows intrinisic drawbacks, such as low hole mobility and conductivity in its pristine form, as well as self-aggregation when deposited as thin film. These are not beneficial properties for efficient hole transport and extraction. In order to address these issues, we have designed a new type of composite hole-transport materials based on a new metal-organic copper complex (CuH) and Spiro-OMeTAD. The incorporation of the molecularly bulky HTM CuH into the Spiro-OMeTAD material efficiently improves the hole mobility and suppresses the aggregation in the Spiro-OMeTAD film. As a result, the conversion efficiencies obtained for perovskite solar cells based on the composite HTM system reached as high as 18.83%, which is superior to solar cells based on the individual hole-transport materials CuH (15.75%) or Spiro-OMeTAD (14.47%) under the same working conditions. These results show that composite HTM systems may constitute an effective strategy to further improve the efficiency of perovskite solar cells.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
Hole transport materials, mobility, perovskite solar cells, small molecules
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-228439 (URN)10.1002/solr.201700073 (DOI)000432036200001 ()
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-05-29Bibliographically approved
Zhang, Y., Yang, X., Wang, W., Wang, X. & Sun, L. (2018). DDQ as an effective p-type dopant for the hole-transport material X1 and its application in stable solid-state dye-sensitized solar cells. Journal of Energy Challenges and Mechanics, 27(2), 413-418
Open this publication in new window or tab >>DDQ as an effective p-type dopant for the hole-transport material X1 and its application in stable solid-state dye-sensitized solar cells
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2018 (English)In: Journal of Energy Challenges and Mechanics, ISSN 2095-4956, E-ISSN 2056-9386, Vol. 27, no 2, p. 413-418Article in journal (Refereed) Published
Abstract [en]

X1 (MeO-TPD) is an inexpensive and easily synthesized pi-conjugated molecule that has been used as a hole-transport material (HTM) in solid-state dye-sensitized solar cells (ssDSSCs), achieving relatively high efficiency. In this paper, we characterize the physicochemical properties of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and show that it is a promising p-dopant in a spin-coating solution with X1 as the HTM. The doped ssDSSCs showed an increase in short-circuit current density from 5.38 mA cm(-2) to 7.39 mA cm(-2), and their overall power conversion efficiency increased from 2.9% to 4.3%. Also, ssDSSCs with DDQ-doped X1 were more stable than the undoped samples, demonstrating that DDQ can act as a p-type dopant in X1 as an HTM for highly efficient, stable ssDSSCs.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
p-Type dopant, X1, DDQ, ssDSSCs
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-224007 (URN)10.1016/j.jechem.2017.12.003 (DOI)000425896100012 ()2-s2.0-85038409600 (Scopus ID)
Note

QC 20180323

Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-03-23Bibliographically approved
Li, F., Yang, H., Li, W. & Sun, L. (2018). Device Fabrication for Water Oxidation, Hydrogen Generation, and CO2 Reduction via Molecular Engineering. JOULE, 2(1), 36-60
Open this publication in new window or tab >>Device Fabrication for Water Oxidation, Hydrogen Generation, and CO2 Reduction via Molecular Engineering
2018 (English)In: JOULE, ISSN 2542-4351, Vol. 2, no 1, p. 36-60Article in journal (Refereed) Published
Abstract [en]

Research on the storage of solar energy in terms of hydrogen or carbon-based fuels by using sunlight to split water or to reduce CO2, respectively, has gained significant attention in recent years. Among reported water-splitting systems, one approach has focused on hybrid systems with molecular catalysts or molecular light-harvesting systems that are combined with nanostructured materials. In this perspective we summarize recent developments in operation and fabrication strategies for various water-splitting devices constructed from electrodes (electrochemical cells) or photoelectrodes (photoelectrochemical cells) using molecular engineering. We also provide insights into the factors that influence device efficiency and stability, and provide guidelines for future fabrication strategies for more advanced devices.

Place, publisher, year, edition, pages
CELL PRESS, 2018
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-224048 (URN)10.1016/j.joule.2017.10.012 (DOI)000425303800009 ()2-s2.0-85041694672 (Scopus ID)
Note

QC 20180320

Available from: 2018-03-20 Created: 2018-03-20 Last updated: 2018-03-20Bibliographically approved
Leandri, V., Daniel, Q., Chen, H., Sun, L., Gardner, J. M. & Kloo, L. (2018). Electronic and Structural Effects of Inner Sphere Coordination of Chloride to a Homoleptic Copper(II) Diimine Complex. Inorganic Chemistry, 57(8), 4556-4562
Open this publication in new window or tab >>Electronic and Structural Effects of Inner Sphere Coordination of Chloride to a Homoleptic Copper(II) Diimine Complex
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2018 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 8, p. 4556-4562Article in journal (Refereed) Published
Abstract [en]

The reaction of CuCl2 with 2,9-dimethyl-1,10-phenanthroline (dmp) does not lead to the formation of [Cu(dmp)(2)](Cl)(2) but instead to [Cu(dmp)(2)Cl]Cl, a 5-coordinated complex, in which one chloride is directly coordinated to the metal center. Attempts at removing the coordinated chloride by changing the counterion by metathesis were unsuccessful and resulted only in the exchange of the noncoordinated chloride, as confirmed from a crystal structure analysis. Complex [Cu-(dmp)(2)Cl]PF6 exhibits a reversible cyclic voltammogram characterized by a significant peak splitting between the reductive and oxidative waves (0.85 and 0.60 V vs NHE, respectively), with a half-wave potential E-1/2 = 0.73 V vs NHE. When reduced electrochemically, the complex does not convert into [Cu(dmp)(2)](+), as one may expect. Instead, [Cu(dmp)(2)](+) is isolated as a product when the reduction of [Cu(dmp)(2)Cl]PF6 is performed with L-ascorbic acid, as confirmed by electrochemistry, NMR spectroscopy, and diffractometry. [Cu(dmp)(2)](2+) complexes can be synthesized starting from Cu(II) salts with weakly and noncoordinating counterions, such as perchlorate. Growth of [Cu(dmp)(2)](ClO4)(2) crystals in acetonitrile results in a 5-coordinated complex, [Cu(dmp)(2)(CH3CN)](ClO4)(2), in which a solvent molecule is coordinated to the metal center. However, solvent coordination is associated with a dynamic decoordination-coordination behavior upon reduction and oxidation. Hence, the cyclic voltammogram of [Cu(dmp)(2)(CH3CN)](2+) is identical to the one of [Cu(dmp)(2)](+), if the measurements are performed in acetonitrile. The current results show that halide ions in precursors to Cu(II) metal-organic coordination compound synthesis, and most likely also other multivalent coordination centers, are not readily exchanged when exposed to presumed strongly binding and chelating ligand, and thus special care needs to be taken with respect to product characterization.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-227776 (URN)10.1021/acs.inorgchem.8b00225 (DOI)000430437400040 ()29608296 (PubMedID)2-s2.0-85045547975 (Scopus ID)
Note

QC 20180514

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-05-14Bibliographically approved
Wang, W., Yang, X., Li, J., Wang, H., An, J., Zhang, L., . . . Sun, L. (2018). Enhancing the Energy-Conversion Efficiency of Solid-State Dye-Sensitized Solar Cells with a Charge-Transfer Complex based on 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone. ENERGY TECHNOLOGY, 6(4), 752-758
Open this publication in new window or tab >>Enhancing the Energy-Conversion Efficiency of Solid-State Dye-Sensitized Solar Cells with a Charge-Transfer Complex based on 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
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2018 (English)In: ENERGY TECHNOLOGY, ISSN 2194-4288, Vol. 6, no 4, p. 752-758Article in journal (Refereed) Published
Abstract [en]

As a champion hole-transporting material (HTM), 2,27,7-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (Spiro-OMeTAD) has been widely used in solid-state dye-sensitized solar cells (ssDSCs). Owing to the low conductivity of Spiro-OMeTAD, a chemical doping strategy is commonly used to enhance its hole-transporting properties. In this study, we report a strong electron acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an additive for Spiro-OMeTAD along with its application in ssDSCs. We show that the conductivity of Spiro-OMeTAD increases from 5.31 x 10(-5) to 2.22 x 10(-4) Scm upon the addition of 0.04% DDQ, and the power conversion efficiency (PCE) of the ssDSCs also increases. By utilizing a donor-pi-acceptor sensitizer with a high coefficient and an HTM with an optimized doping ratio, we were able to achieve a high PCE of 6.37% for the ssDSCs under 10 0mWcm(-2) AM1.5G simulated illumination, in comparison to the PCE of the pristine device, which was only 3.50%. An increase in the application of benzoquinone-based materials for organic electronics is expected, especially for solar-cell applications.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
charge transfer, dye-sensitized solar cells, donor-acceptor systems, photovoltaics, sensitizers
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-227234 (URN)10.1002/ente.201700633 (DOI)000430104000017 ()2-s2.0-85041754073 (Scopus ID)
Note

QC 20180514

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-05-14Bibliographically approved
Yao, Y., Gao, Y., Ye, L., Chen, H. & Sun, L. (2018). Highly efficient photocatalytic reduction of CO2 and H2O to CO and H-2 with a cobalt bipyridyl complex. Journal of Energy Challenges and Mechanics, 27(2), 502-506
Open this publication in new window or tab >>Highly efficient photocatalytic reduction of CO2 and H2O to CO and H-2 with a cobalt bipyridyl complex
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2018 (English)In: Journal of Energy Challenges and Mechanics, ISSN 2095-4956, E-ISSN 2056-9386, Vol. 27, no 2, p. 502-506Article in journal (Refereed) Published
Abstract [en]

The development of efficient molecular catalysts for visible-light driven CO2 reduction, based on abundant materials, is necessary to meet energy demands and address environment problems. In this work, a Co(bpy)(2)Cl-2 catalyst was developed and showed high efficiency and durability for the photocatalytic reduction of CO2 and protons. Yields of CO and H-2 as high as 62.3 and 69.9 mu mol were achieved and the turnover numbers (TONs) reached 6230 and 6990, respectively, under light irradiation (lambda > 420 nm) for 4 h, indicating that the mixture gases could be a candidate as syngas. The apparent quantum yield was determined to be 2.1% for CO. Mechanistic studies revealed oxidative quenching of the photosensitizer Ru(bpy)(3)Cl-2 by the catalyst. The photocatalytic performance, flexible synthesis and non-noble metal catalyst in our system show great promise for the practical application of Co(bpy)(2)Cl-2 to photocatalytic reduction of CO2.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Cobalt catalyst, Photocatalysis, CO2 reduction, Oxidative quenching
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-224008 (URN)10.1016/j.jechem.2017.11.012 (DOI)000425896100024 ()2-s2.0-85041674763 (Scopus ID)
Note

QC 20180323

Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-05-24Bibliographically approved
Qu, J., Jiang, X., Yu, Z., Lai, J., Zhao, Y., Hu, M., . . . Sun, L. (2018). Improved performance and air stability of perovskite solar cells based on low-cost organic hole-transporting material X60 by incorporating its dicationic salt. Science in China Series B: Chemistry, 61(2), 172-179
Open this publication in new window or tab >>Improved performance and air stability of perovskite solar cells based on low-cost organic hole-transporting material X60 by incorporating its dicationic salt
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2018 (English)In: Science in China Series B: Chemistry, ISSN 1674-7291, E-ISSN 1869-1870, Vol. 61, no 2, p. 172-179Article in journal (Refereed) Published
Abstract [en]

The development of an efficient, stable, and low-cost hole-transporting material (HTM) is of great significance for perovskite solar cells (PSCs) from future commercialization point of view. Herein, we specifically synthesize a dicationic salt of X60 termed X60(TFSI)(2), and adopt it as an effective and stable "doping" agent to replace the previously used lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) for the low-cost organic HTM X60 in PSCs. The incorporation of this dicationic salt significantly increases the hole conductivity of X60 by two orders of magnitude from 10(-6) to 10(-4) S cm(-1). The dramatic enhancement of the conductivity leads to an impressive power conversion efficiency (PCE) of 19.0% measured at 1 sun illumination (100 mW cm(-2), AM 1.5 G), which is comparable to that of the device doped with LiTFSI (19.3%) under an identical condition. More strikingly, by replacing LiTFSI, the PSC devices incorporating X60(TFSI)(2) also show an excellent long-term durability under ambient atmosphere for 30 days, mainly due to the hydrophobic nature of the X60(TFSI)(2) doped HTM layer, which can effectively prevent the moisture destroying the perovskite layer. The present work paves the way for the development of highly efficient, stable, and low-cost HTM for potential commercialization of PSCs.

Place, publisher, year, edition, pages
Science Press, 2018
Keywords
perovskite solar cells, hole-transporting materials, X60, stability, sustainable energy
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-223271 (URN)10.1007/s11426-017-9141-9 (DOI)000424012300006 ()
Funder
Swedish Foundation for Strategic Research Swedish Energy AgencyKnut and Alice Wallenberg Foundation
Note

QC 20180216

Available from: 2018-02-16 Created: 2018-02-16 Last updated: 2018-02-16Bibliographically approved
Yang, H., Li, F., Wu, X., Zhang, P., Li, W., Cao, S., . . . Sun, L. (2018). Improving the performance of water splitting electrodes by composite plating with nano-SiO2. Electrochimica Acta, 281, 60-68
Open this publication in new window or tab >>Improving the performance of water splitting electrodes by composite plating with nano-SiO2
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2018 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 281, p. 60-68Article in journal (Refereed) Published
Abstract [en]

The electrochemical splitting of water requires efficient functional electrodes. Herein, we report the fabrication of electrocatalyst consisted of an electrodeposited NiFeP alloy film which was composite plated with nano-SiO2 on nickel foam. The structure and morphology of the film were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the surface area of this NiFeP-SiO2 co-deposition alloy film can be significantly increased after electrochemical etching in a KOH solution. The water splitting properties of the alloy film were evaluated using electrochemistry. By using the NiFeP-SiO2/NF(Etched) as a bifunctional electrode, total water splitting has been demonstrated in a two-electrode cell with a current density of 10 mAcm(-2) at an applied voltage of 1.57 V, which exhibited enhanced water splitting activity in comparison to the analogue cell using the pristine NiFeP/NF electrode.

Place, publisher, year, edition, pages
Pergamon Press, 2018
Keywords
Composite plating, Nano-SiO2, Water splitting, Electrodes, Alloy films
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-232748 (URN)10.1016/j.electacta.2018.05.163 (DOI)000439134600008 ()2-s2.0-85047509091 (Scopus ID)
Funder
Swedish Research Council, 2017-00935Swedish Energy Agency
Note

QC 20180807

Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2018-08-07Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4521-2870

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