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Wang, Lei
Publications (5 of 5) Show all publications
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
Wang, L., Yin, X., Esquius-Morote, M., Zhao, H. & Mosig, J. R. (2017). Circularly Polarized Compact LTSA Array in SIW Technology. IEEE Transactions on Antennas and Propagation, 65(6), 3247-3252
Open this publication in new window or tab >>Circularly Polarized Compact LTSA Array in SIW Technology
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2017 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 65, no 6, p. 3247-3252Article in journal (Refereed) Published
Abstract [en]

Typical linearly tapered slot antenna (LTSA) usually features a wideband and a high gain. However, its geometry size is large, especially very long in the tapering direction, which limits its application in compact antenna and array systems. This communication has minimized the tapered length to less than 0.19 lambda(0) when the aperture width is less than 0.35 lambda(0) both for horizontally and vertically polarized LTSA arrays. Moreover, the typical polarization of the LTSA is linear, which is perpendicular to the slot. In this communication, an X-band circularly polarized 1x8 LTSA array, made of cross-LTSAs, is proposed with the feeding of a substrate integrated waveguide horn. All the three different polarized LTSA arrays are designed and investigated both in simulation and experiment, and the simulation results agree well with the measured results.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
Antipodal linearly tapered slot antenna (ALTSA), circular polarization, linearly tapered slot antenna (LTSA), substrate integrated waveguide (SIW)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-210485 (URN)10.1109/TAP.2017.2696955 (DOI)000402731400055 ()2-s2.0-85021743445 (Scopus ID)
Note

QC 20170705

Available from: 2017-07-05 Created: 2017-07-05 Last updated: 2018-09-19Bibliographically approved
Jonsson, B. L., Shi, S., Wang, L., Ferrero, F. & Lizzi, L. (2017). On Methods to Determine Bounds on the Q-Factor for a Given Directivity. IEEE Transactions on Antennas and Propagation, 65(11), 5686-5696
Open this publication in new window or tab >>On Methods to Determine Bounds on the Q-Factor for a Given Directivity
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2017 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 65, no 11, p. 5686-5696Article in journal (Refereed) Published
Abstract [en]

This paper revisit and extend the interesting case of bounds on the Q-factor for a given directivity for a small antenna of arbitrary shape. A higher directivity in a small antenna is closely connected with a narrow impedance bandwidth. The relation between bandwidth and a desired directivity is still not fully understood, not even for small antennas. Initial investigations in this direction have related the radius of a circumscribing sphere to the directivity, and bounds on the Q-factor have also been derived for a partial directivity in a given direction. In this paper, we derive lower bounds on the Q-factor for a total desired directivity for an arbitrarily shaped antenna in a given direction as a convex problem using semidefinite relaxation (SDR) techniques. We also show that the relaxed solution is also a solution of the original problem of determining the lower Q-factor bound for a total desired directivity. SDR can also be used to relax a class of other interesting nonconvex constraints in antenna optimization, such as tuning, losses, and front-to-back ratio. We compare two different new methods to determine the lowest Q-factor for arbitrary-shaped antennas for a given total directivity. We also compare our results with full electromagnetic simulations of a parasitic element antenna with high directivity.

Place, publisher, year, edition, pages
IEEE, 2017
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-218217 (URN)10.1109/TAP.2017.2748383 (DOI)000414047400003 ()
Note

QC 20171128

Available from: 2017-11-28 Created: 2017-11-28 Last updated: 2018-11-15Bibliographically approved
Shi, S., Jonsson, B. L., Ferrero, F. & Wang, L.An Investigation of the Bandwidth Optimal Position of an Embedded Antenna.
Open this publication in new window or tab >>An Investigation of the Bandwidth Optimal Position of an Embedded Antenna
(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-239131 (URN)
Note

QC 20181116

Available from: 2018-11-16 Created: 2018-11-16 Last updated: 2018-11-16Bibliographically approved
Shi, S., Wang, L. & Jonsson, B. L. Antenna Current Optimization and Realizations for Far-Field Pattern Shaping.
Open this publication in new window or tab >>Antenna Current Optimization and Realizations for Far-Field Pattern Shaping
(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-239130 (URN)
Note

QC 20181116

Available from: 2018-11-16 Created: 2018-11-16 Last updated: 2018-11-16Bibliographically approved
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