Publications at the Institute of Physics

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Zhou, Yujia; Wang, Zidong; Zheng, Chunfang; Fu, Qun; Wu, Minghong; Zhao, Huaping; Lei, Yong;
Construction of Co0.85Se@nickel nanopores array hybrid electrode for high-performance asymmetric supercapacitors. - In: Chemical engineering science. - Amsterdam [u.a.] : Elsevier Science, Bd. 247 (2022), 117081, S. 1-9

Nanostructured current collectors have larger specific surface area and short ion/electron transport path, which are highly desirable for supercapacitors applications. Herein, Co0.85SeNiNPs (Co0.85Se@NiNP) hybrid electrodes are proposed and fabricated, in which NiNP is served as nanostructured current collectors. NiNP has a vertical pore structure and a large specific surface area, which could effectively promote the ion/electron transport efficiency and reduce internal electrical resistance. Compared with Ni foam and Ni foil as current collectors, NiNP enables Co0.85Se@NiNP electrodes show significantly improved specific capacity, rate performance and cycle stability. Finally, an asymmetric supercapacitor device was assembled with Co0.85Se@NiNP hybrid electrode as the binder-free positive electrode and activated carbon (AC) coated on nickel foam as negative electrode. The Co0.85Se@NiNP//AC asymmetric supercapacitors can work in a wide potential window of 0 - 1.6 V with an ultrahigh specific capacity of 182.3 F g^-1 at 1 A g^-1. Most importantly, Co0.85Se@NiNP//AC has a high energy density of 64.81 Wh kg^-1 at 800 W kg^-1 and an outstanding cycle stability of up to 12000 cycles, indicating that Co0.85Se@NiNP electrode has great application potential in supercapacitors.
Zhang, Huanming; Zhou, Min; Zhao, Huaping; Lei, Yong;
Ordered nanostructures arrays fabricated by anodic aluminum oxide (AAO) template-directed methods for energy conversion. - In: Nanotechnology. - Bristol : IOP Publ., ISSN 1361-6528, Bd. 32 (2021), 50, S. 1-27

Clean and efficient energy conversion systems can overcome the depletion of the fossil fuel and meet the increasing demand of the energy. Ordered nanostructures arrays convert energy more efficiently than their disordered counterparts, by virtue of their structural merits. Among various fabrication methods of these ordered nanostructures arrays, anodic aluminum oxide (AAO) template-directed fabrication have drawn increasing attention due to its low cost, high throughput, flexibility and high structural controllability. This article reviews the application of ordered nanostructures arrays fabricated by AAO template-directed methods in mechanical energy, solar energy, electrical energy and chemical energy conversions in four sections. In each section, the corresponding advantages of these ordered nanostructures arrays in the energy conversion system are analysed, and the limitation of the to-date research is evaluated. Finally, the future directions of the ordered nanostructures arrays fabricated by AAO template-directed methods (the promising method to explore new growth mechanisms of AAO, green fabrication based on reusable AAO templates, new potential energy conversion application) are discussed.
Zhao, Xingxing; Zhang, Chenglin; Yang, Guowei; Wu, Yuhan; Fu, Qun; Zhao, Huaping; Lei, Yong;
Bismuth selenide nanosheets confined in thin carbon layers as anode materials for advanced potassium-ion batteries. - In: Inorganic chemistry frontiers : an international journal of inorganic chemistry.. - Cambridge : RSC, ISSN 2052-1553, Bd. 8 (2021), 18, S. 4267-4275

Metal selenides as promising anode materials for potassium ion batteries (PIBs) have attracted great research attention. However, it is still a challenge to promote its practical application due to the unsatisfactory cyclability resulting from large volume variation and sluggish kinetics. Herein, we tackle this issue by focusing on a promising but undemonstrated anode, bismuth selenide for PIBs which possesses a high theoretical capacity and good electronic conductivity. Benefitting from the carbon layer coating, Bi2Se3C has the capability to inhibit self-aggregation and buffer the volume expansion, leading to outstanding potassium-ion storage capability. It exhibits a very high reversible capacity of 526 mA h g^-1 at 50 mA g^-1, as well as superior cyclability and rate capability while maintaining a high capacity of 214 mA h g^-1 at 1.0 A g^-1 after 1000 cycles. Furthermore, its fast and reversible ion storage mechanism was verified, which first involves conversion and subsequent alloying redox reactions. This work enriches the understanding and development of stable conversion/alloying-based anodes for high-performance potassium-ion batteries.
Lindt, Kevin; Gizatullin, Bulat; Mattea, Carlos; Stapf, Siegfried;
Non-exponential 1H and 2H NMR relaxation and self-diffusion in asphaltene-maltene solutions. - In: Molecules : a journal of synthetic chemistry and natural product chemistry.. - Basel : MDPI, ISSN 1420-3049, Bd. 26 (2021), 17, S. 1-35
- Im Titel sind "1" und "2" hochgestellt

The distribution of NMR relaxation times and diffusion coefficients in crude oils results from the vast number of different chemical species. In addition, the presence of asphaltenes provides different relaxation environments for the maltenes, generated by steric hindrance in the asphaltene aggregates and possibly by the spatial distribution of radicals. Since the dynamics of the maltenes is further modified by the interactions between maltenes and asphaltenes, these interactions - either through steric hindrances or promoted by aromatic-aromatic interactions - are of particular interest. Here, we aim at investigating the interaction between individual protonic and deuterated maltene species of different molecular size and aromaticity and the asphaltene macroaggregates by comparing the maltenes NMR relaxation (T1 and T2) and translational diffusion (D) properties in the absence and presence of the asphaltene in model solutions. The ratio of the average transverse and longitudinal relaxation rates, describing the non-exponential relaxation of the maltenes in the presence of the asphaltene, and its variation with respect to the asphaltene-free solutions are discussed. The relaxation experiments reveal an apparent slowing down of the maltenes dynamics in the presence of asphaltenes, which differs between the individual maltenes. While for single-chained alkylbenzenes, a plateau of the relaxation rate ratio was found for long aliphatic chains, no impact of the maltenes aromaticity on the maltene-asphaltene interaction was unambiguously found. In contrast, the reduced diffusion coefficients of the maltenes in presence of the asphaltenes differ little and are attributed to the overall increased viscosity.
Emminger, Carola; Abadizaman, Farzin; Samarasingha, Nuwanjula S.; Menéndez, José; Espinoza, Shirly; Richter, Steffen; Rebarz, Mateusz; Herrfurth, Oliver; Zahradník, Martin; Schmidt-Grund, Rüdiger; Andreasson, Jakob; Zollner, Stefan;
Analysis of temperature-dependent and time-resolved ellipsometry spectra of Ge. - In: IEEE Xplore digital library. - New York, NY : IEEE, ISSN 2473-2001, (2021), , insges. 2 S.
Paszuk, Agnieszka; Nandy, Manali; Kleinschmidt, Peter; Hannappel, Thomas;
In situ monitoring of As-P exchange on Ge(100) surfaces in GaAs-rich CVD reactors for low-defect III-V multijunction solar cells. - In: IEEE Xplore digital library. - New York, NY : IEEE, ISSN 2473-2001, (2021), , S. 339-341
Nandy, Manali; Paszuk, Agnieszka; Feifel, Markus; Koppka, Christian; Kleinschmidt, Peter; Dimroth, Frank; Hannappel, Thomas;
Reduction of defects in GaP layers grown on Si(100) by MOCVD. - In: IEEE Xplore digital library. - New York, NY : IEEE, ISSN 2473-2001, (2021), , S. 1344-1347
Mehler, Alexander; Néel, Nicolas; Voloshina, Elena; Dedkov, Yuriy; Kröger, Jörg;
Second floor of flatland: epitaxial growth of graphene on hexagonal boron nitride. - In: Small : nano micro.. - Weinheim : Wiley-VCH, ISSN 1613-6829, Bd. 17 (2021), 36, S. 1-9

In the studies presented here, the subsequent growth of graphene on hexagonal boron nitride (h-BN) is achieved by the thermal decomposition of molecular precursors and the catalytic assistance of metal substrates. The epitaxial growth of h-BN on Pt(111) is followed by the deposition of a temporary Pt film that acts as a catalyst for the fabrication of the graphene sheet. After intercalation of the intermediate Pt film underneath the boron-nitride mesh, graphene resides on top of h-BN. Scanning tunneling microscopy and density functional calculations reveal that the moiré pattern of the van-der-Waals-coupled double layer is due to the interface of h-BN and Pt(111). While on Pt(111) the graphene honeycomb unit cells uniformly appear as depressions using a clean metal tip for imaging, on h-BN they are arranged in a honeycomb lattice where six protruding unit cells enframe a topographically dark cell. This superstructure is most clearly observed at small probe-surface distances. Spatially resolved inelastic electron tunneling spectroscopy enables the detection of a previously predicted acoustic hybrid phonon of the stacked materials. Its' spectroscopic signature is visible in surface regions where the single graphene sheet on Pt(111) transitions into the top layer of the stacking.
Cretu, Andrea; Mattea, Carlos; Stapf, Siegfried;
Low-field and variable-field NMR relaxation studies of H2O and D2O molecular dynamics in articular cartilage. - In: PLOS ONE. - San Francisco, California, US : PLOS, ISSN 1932-6203, Bd. 16 (2021), 8, S. 1-34
- Im Titel ist "2" tiefgestellt
Zhang, Keyu; Cui, Dingfang; Huang, Xiaopeng; Liang, Feng; Gao, Geng; Song, Tingyu; Zhang, Libo; Yao, Yaochun; Lei, Yong;
Insights into the interfacial chemistry and conversion mechanism of iron oxalate toward the reduction by lithium. - In: The chemical engineering journal. - Amsterdam : Elsevier, ISSN 1873-3212, Bd. 426 (2021), 131446

The origin of excellent lithium storage ability and high irreversible capacity is probably the least understood component for transition-metal oxalates as anode materials in lithium-ion batteries. Considerable efforts have been put into understanding their electrochemical reaction mechanisms, but these insights have mostly been unilateral and unsystematic. Herein, the interface characteristic between iron oxalate anode and electrolyte and detailed conversion process were investigated to explore the source of irreversible Li+ storage. In particular, a gelatinous "organic" layer identified oxygen, fluorine and phosphorus as the main chemical elements can be re-oxidized and exhibits an obviously reversible conversion between sedimentation and decomposition during its initial lithiation process, despite the general belief that it shows similar electrochemically inert to solid-electrolyte interphase (SEI). Meanwhile, this special interface layer leads to higher ability of Li+ ions diffusion and smaller charge-transfer resistance, which is the vital role for excellent rate capability. Furthermore, ex situ FTIR analysis confirms the formation and residue of new intermediate compound of Li2Fe(C2O4)2, thus making a part of initial irreversible capacity. It is also found that the iron oxalate electrode with larger capacitive contribution still has more widely application in energy storage of supercapacitors in future.