Publikationen an der Fakultät für Mathematik und Naturwissenschaften ab 2019

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Hu, Ping; Dong, Yulian; Yang, Guowei; Chao, Xin; He, Shijiang; Zhao, Huaping; Fu, Qun; Lei, Yong
Hollow CuSbSy coated by nitrogen-doped carbon as anode electrode for high-performance potassium-ion storage. - In: Batteries, ISSN 2313-0105, Bd. 9 (2023), 5, 238, S. 1-15

As a potential anode material for potassium-ion batteries (PIBs), bimetallic sulfides are favored by researchers for their high specific capacity, low cost, and long cycle life. However, the non-ideal diffusion rate and poor cycle stability pose significant challenges in practical applications. In this work, bimetallic sulfide CuSbSyC with a yolk-shell structure was synthesized by in situ precipitation and carbonization. When CuSbSy is applied in the anode of PIBs, it can provide the desired capacity and reduce the volume expansion of the compound through the synergistic effect between copper and antimony. At the same time, the existence of the nitrogen-doped carbon shell confines the material within the shell while improving its electrical conductivity, inhibiting its volume expansion and aggregation. Therefore, CuSbSy@C exhibits a satisfactory capacity (438.8 mAh g^-1 at 100 mA g^-1 after 60 cycles) and an excellent long cycle life (174.5 mAh g^-1 at 1000 mA g^-1 after 1000 cycles).
Hu, Yongxu; Wang, Zhongwu; Huang, Yinan; Shi, Rui; Wang, Shuguang; Chen, Xiaosong; Bi, Jinshun; Xuan, Yundong; Lei, Yong; Li, Liqiang; Yang, Chuluo; Hu, Wenping
Deep ultraviolet phototransistor based on thiophene-fluorobenzene oligomer with high mobility and performance. - In: Chinese journal of chemistry, ISSN 1614-7065, Bd. 41 (2023), 13, S. 1539-1544

Deep ultraviolet (UV) photodetectors have important applications in the industrial and military fields. However, little research has been reported on organic phototransistors (OPTs) in the deep ultraviolet range. Here, a novel organic semiconductor containing a small torsion angle and low π-conjugation 2,2':5',2”-terthiophene groups, oF-PTTTP, is designed and synthesized, which exhibits high carrier mobility and unique deep ultraviolet response. Accordingly, an OPT based on oF-PTTTP single crystal shows high responsivity to deep-UV light. The photodetectors achieve high photoresponsivity (R) of 857 A/W and detectivity (D*) of 3.2×10^15 Jones under 280 nm light illumination (only 95 nW&hahog;cm^-2). To the best of our knowledge, 280 nm is the deepest detection wavelength reported for organic phototransistors and this work presents a new molecule design concept for organic phototransistors with deep-UV detection.
Niu, Wenhui; Xu, Bowen; Li, Fupeng; Hou, Minjie; Ren, Kun; Zhang, Da; Lei, Yong; Yang, Bin; Liang, Feng
Hierarchical mesoporous NiO nanosheet arrays as integrated electrode for hybrid sodium-air batteries. - In: Ceramics international, ISSN 0272-8842, Bd. 49 (2023), 13, S. 21355-21362

Attributed to its environmental friendliness, high theoretical energy density, and abundant sodium resource, rechargeable hybrid sodium-air batteries (HSABs) are expected to become a promising pioneer of the new-generation green energy storage device. However, HSABs suffer from the high voltage gap, low energy conversion efficiency, and poor cycle stability due to the low catalytic activity of catalysts caused by the degradation of polymer binders. Herein, hierarchical mesoporous NiO nanosheet arrays grown on carbon papers (CP) (NiO NACP) were synthesized by a facile and efficient hydrothermal route and calcination process, which acts as an integrated electrode for HSABs. Compared with traditional air electrodes that contain a polymer binder and conductive carbon, the integrated NiO NA@CP electrode prevents the aggregation of catalysts, improves the electronic conductivity by good electric contact and ensures its robust mechanical stability. In addition, NiO NA@CP electrode with the abundant porosity and large specific area offers plenty of active sites and shortens ion transfer length and rapid mass transport in ORR/OER process, leading to excellent oxygen catalytic activities. HSABs with NiO NA@CP electrode show a low overpotential of 0.65 V, a state-of-the-art power density (7.53 mW cm^-2), as well as an excellent cyclability of 170 cycles (over 170 h) at a current density of 0.1 mA cm^-2.
Faulwasser, Timm; Ou, Ruchuan; Pan, Guanru; Schmitz, Philipp; Worthmann, Karl
Behavioral theory for stochastic systems? A data-driven journey from Willems to Wiener and back again. - In: Annual reviews in control, ISSN 1872-9088, Bd. 55 (2023), S. 92-117

The fundamental lemma by Jan C. Willems and co-workers is deeply rooted in behavioral systems theory and it has become one of the supporting pillars of the recent progress on data-driven control and system analysis. This tutorial-style paper combines recent insights into stochastic and descriptor-system formulations of the lemma to further extend and broaden the formal basis for behavioral theory of stochastic linear systems. We show that series expansions - in particular Polynomial Chaos Expansions (PCE) of L2-random variables, which date back to Norbert Wiener’s seminal work - enable equivalent behavioral characterizations of linear stochastic systems. Specifically, we prove that under mild assumptions the behavior of the dynamics of the L2-random variables is equivalent to the behavior of the dynamics of the series expansion coefficients and that it entails the behavior composed of sampled realization trajectories. We also illustrate the short-comings of the behavior associated to the time-evolution of the statistical moments. The paper culminates in the formulation of the stochastic fundamental lemma for linear time-invariant systems, which in turn enables numerically tractable formulations of data-driven stochastic optimal control combining Hankel matrices in realization data (i.e. in measurements) with PCE concepts.
Zhang, Chenglin; Chandan Solanki, Pankaj; Cao, Dawei; Zhao, Huaping; Lei, Yong
Integration of cointercalation and adsorption enabling superior rate performance of carbon anodes for symmetric sodium-ion capacitors. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 15 (2023), 20, S. 24459-24469

Carbon materials have been the most common anodes for sodium-ion storage. However, it is well-known that most carbon materials cannot obtain a satisfactory rate performance because of the sluggish kinetics of large-sized sodium-ion intercalation in ordered carbon layers. Here, we propose an integration of co-intercalation and adsorption instead of conventional simplex-intercalation and adsorption to promote the rate capability of sodium-ion storage in carbon materials. The experiment was demonstrated by using a typical carbon material, reduced graphite oxide (RGO400) in an ether-solvent electrolyte. The ordered and disordered carbon layers efficiently store solvated sodium ions and simplex sodium ions, which endows RGO400 with enhanced reversible capacity (403 mA h g^-1 at 50 mA g^-1 after 100 cycles) and superior rate performance (166 mA h g^-1 at 20 A g^-1). Furthermore, a symmetric sodium-ion capacitor was demonstrated by employing RGO400 as both the anode and cathode. It exhibits a high energy density of 48 W h g^-1 at a very high power density of 10,896 W kg^-1. This work updates the sodium-ion storage mechanism and provides a rational strategy to realize high rate capability for carbon electrode materials.
Peng, Xuanran; Liu, Jing; Kang, Yaru; Mao, Xu; Yan, Wei; Wang, Xiaohui; Liu, Kong; Xu, Rui; Yang, Fuhua; Li, Zhaofeng
Coupling of photonic and plasmonic modes for double nanowire cavities. - In: Photonics, ISSN 2304-6732, Bd. 10 (2023), 4, 415, S. 1-11

We analyze the coupling between double nanowire cavities for both photonic modes and plasmonic modes. When the spacing between nanowires reduces, a redshift of the resonant frequency of the symmetric mode and a blueshift of the resonant frequency of the antisymmetric mode are observed. Compared to single nanowire cavity modes, the Q factors of antisymmetric supermodes of double nanowires can be improved by 51% for photonic modes and by 24% for plasmonic modes. The mechanisms of Q factor improvement for photonic modes and plasmonic modes are studied based on the field distribution of radiations from the modes. This paper may contribute to research and applications for double nanowire lasers and nanowire laser arrays.
Meinecke, Stefan; Köster, Felix; Christiansen, Dominik; Lüdge, Kathy; Knorr, Andreas; Selig, Malte
Data-driven forecasting of nonequilibrium solid-state dynamics. - In: Physical review, ISSN 1550-235X, Bd. 107 (2023), 18, S. 184306-1-184306-18

We present a data-driven approach to efficiently approximate nonlinear transient dynamics in solid-state systems. Our proposed machine-learning model combines a dimensionality reduction stage with a nonlinear vector autoregression scheme. We report an outstanding time-series forecasting performance combined with an easy-to-deploy model and an inexpensive training routine. Our results are of great relevance as they have the potential to massively accelerate multiphysics simulation software and thereby guide the future development of solid-state-based technologies.
He, Shijiang; Wang, Zidong; Wang, Zhijie; Lei, Yong
Recent progress and future prospect of novel multi-ion storage devices. - In: Journal of semiconductors, ISSN 2058-6140, Bd. 44 (2023), 4, 040201, S. 1-5
Chan, Tsz Lung; Kriesell, Matthias; Schmidt, Jens M.
Contractible edges in longest cycles. - In: Journal of graph theory, ISSN 1097-0118, Bd. 103 (2023), 3, S. 542-563
Omidian, Maryam; Brand, Jonathan; Néel, Nicolas; Crampin, Simon; Kröger, Jörg
From a wide band gap to the superconducting proximity effect: Fe on Pb(111). - In: New journal of physics, ISSN 1367-2630, Bd. 25 (2023), 3, 033036, insges. 1-15 S.

Epitaxially grown Fe nanostructures on Pb(111) were studied by low-temperature scanning tunneling microscopy and spectroscopy. The deposited Fe assemblies are classified into two groups according to their electronic behavior close to the Fermi energy. One group exhibits a wide energy gap of 0.7 eV that is independent of the temperature ranging from 5 K to room temperature. These Fe islands indicate the absence of the superconductivity proximity effect in their interior. The other group shows a metallic behavior at the Fermi level. The substrate superconducting phase locally enters into these islands, which is evidenced by a sharp resonance at the Fermi energy presumably signaling Andreev reflection at the magnet-superconductor interface.