Centimeter-scale gold nanoparticle arrays for spatial mapping of the second harmonic and two-photon luminescence. - In: ACS applied nano materials, ISSN 2574-0970, Bd. 4 (2021), 11, S. 11563-11572
Fabricating highly homogeneous plasmonic nanostructures over a large area and optically evaluating their structural quality are challenging. Here, we propose an elegant approach to achieve various dense nanoparticle arrays with tunable symmetries over centimeter-scale dimensions and optically evaluate the structural quality by spatially mapping nonlinear emissions from L-, U-, and O-shaped individual nanoparticles. In particular, the spectral overlapping of the second harmonic (SH) and two-photon luminescence (TPL) emissions is separated, and excitation polarization dependence and spatial fluctuations of the nonlinear signal across the nanostructures are investigated. Narrow Gaussian-distributed peaks in the intensity histogram of SH and TPL emissions confirm the high-level uniformity of the fabricated arrays. Distinct spatial distributions of SH and TPL emissions are observed, and their spatial correlation is very weak over large-area nanostructures. Furthermore, SH signals are demonstrated as a more sensitive indicator of the structural quality of nanoparticle arrays. Our findings not only offer an efficient way of constructing versatile large-scale nanostructures but also enable spatial nonlinear optics tailoring for applications of nano-optics and quantum information.
https://doi.org/10.1021/acsanm.1c02020
Vertical few-layer WSe2 nanosheets for NO2 sensing. - In: ACS applied nano materials, ISSN 2574-0970, Bd. 4 (2021), 11, S. 12043-12050
WSe2 has been widely used in NO2 gas sensors in recent years, but it still suffers from low responsiveness and slow reaction kinetics. Herein, we used the chemical vapor deposition method to synthesize a vertically grown few-layer WSe2 (3D-WSe2) nanosheet film. Three-dimensional-WSe2 is transformed into vertical growth by introducing a TiO2 buffer layer and exposes much more edge active sites to improve gas sensitivity. As a result, it has not only high crystallinity and few defects but also a high response to NO2 (34.6% at 1 ppm), a fast response time (66 s), a short recovery time (17 min), a low limit of detection (4 ppb), excellent stability, and gas selectivity at room temperature.
https://doi.org/10.1021/acsanm.1c02603
A porous current collector cleaner enables thin cathode electrolyte interphase on LiCoO2 for stable high-voltage cycling. - In: Journal of materials chemistry, ISSN 2050-7496, Bd. 9 (2021), 47, S. 26989-26998
LiCoO2 (LCO) is the most successful commercial cathode for lithium-ion batteries due to its high theoretical specific capacity (274 mA h g^-1). However, LCO-based batteries show a significantly high degree of instability in cycling performance and severe capacity fading as voltages exceed 4.35 V versus Li/Li+. Herein, a carbon nanotube macrofilm (CMF) was used as a current collector for addressing the long-standing issues, which demonstrate LCO with the first specific capacities of 191.1 and 180.1 mA h g^-1 after 300 cycles, at 4.5 V. The excellent results are ascribed to the interactions between decomposed electrolytes and carbon nanotubes, which ensure that decomposition products around the cathode are cleaned timely by the current collector cleaner. Therefore an ultrathin cathode electrolyte interphase is obtained and keeps the feature in the subsequent cycles. The assembled LCO-based pouch cell also indicates a high energy density of 523 W h kg^-1 after 200 cycles. This work presents novel insights into cathodes with stable cycling at high voltages.
https://doi.org/10.1039/D1TA07268D
Optical properties of nanoporous gold sponges using model structures obtained from three-dimensional phase-field Simulation. - In: 2021 Photonics & Electromagnetics Research Symposium (PIERS), (2021), S. 517-523
Nanoporous sponge structures show fascinating optical properties related to a strong spatial localization of field modes and a resulting strong field enhancement. In this work, a novel efficient method for the generation of three-dimensional nanoporous sponge structures using time-resolved phase-field simulations is presented. The algorithm for creating the geometries and the underlying equations are discussed. Different sponge geometries are generated and compared with sponges that have been experimentally measured using FIB tomography. Meaningful parameters are defined for the comparison of the geometric properties of the random sponge structures. In addition, the optical properties of the simulated sponges are compared with the experimentally measured sponges. It is shown that a description using effective media does not provide a good agreement to the actual spectra. This shows that the optical properties are largely determined by the local structures. In contrast, the numerically obtained spectra of the phase-field sponge models accounting for the real-space structure show excellent agreement with the spectra of the experimentally measured sponges.
https://doi.org/10.1109/PIERS53385.2021.9694971
Optimal vibration analysis for a combustion motor. - In: Proceedings of the 16th IEEE Conference on Industrial Electronics and Applications (ICIEA 2021), (2021), S. 166-170
Combustion motors have quite important uses in Peru due to capacity of energy that is achieved to solve multiple tasks, such as for example public transport, mining and factories. However, a big disadvantage is given owing to pollution that is produced through them. Therefore, there are many proposal solutions as for example, optimal control over physical variables, which have information of consumed fuel. Nevertheless, it gets complications in interesting (but longer) algorithms as strategies. That is the reason, why in this research is proposed a mathematical procedure that is correlated with faster and robust sensors/actuators according to achieve an enhancement performance over the efficiency of combustion motors.
https://doi.org/10.1109/ICIEA51954.2021.9516132
Active noise cancellation techniques to enhance audition in noisy cities. - In: 2021 IEEE International Conference on Mechatronics and Automation, (2021), S. 148-151
It is proposed in this research some suggestions and applications to enhance and care of the hearing health in noisy cities, such as for example, the noise that is caused by traffic, engines from factories and imprudent behavior from drivers and street sellers (as it happens in Peruvian cities). In this research, it was analyzed many techniques according to propose enhancement of the health audition by engineering analysis of the noise cancellation and advanced sensors/actuators (microphones and loudspeakers) that were based in nanostructures, because to achieve this objective. Therefore, it is expected that this research could be a support for institutions, which need technical analysis results, regarding to study the necessity to care the hearing health in noisy cities, such as for example, many hospitals, homes, universities and schools that are located near noisy avenues cannot get attenuation of noise, if there are not noise cancellation systems to care the hearing health.
https://doi.org/10.1109/ICMA52036.2021.9512571
Carbon-free crystal-like Fe1-xS as an anode for potassium-ion batteries. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 13 (2021), 46, S. 55218-55226
Im Titel ist "1-x" tiefgestellt
Potassium-ion batteries (PIBs) as a new electrochemical energy storage system have been considered as a desirable candidate in the post-lithium-ion battery era. Nevertheless, the study on this realm is in its infancy; it is urgent to develop electrode materials with high electrochemical performance and low cost. Iron sulfides as anode materials have aroused wide attention by virtue of their merits of high theoretical capacities, environmental benignity, and cost competitiveness. Herein, we constructed carbon-free crystal-like Fe1-xS and demonstrated its feasibility as a PIB anode. The unique structural feature endows the prepared Fe1-xS with plentiful active sites for electrochemical reactions and short transmission pathways for ions/electrons. The Fe1-xS electrode retained capacities of 420.8 mAh g-1 after 100 cycles at 0.1 A g-1 and 212.9 mAh g-1 after 250 cycles at 1.0 A g-1. Even at a high rate of 5.0 A g-1, an average capacity of 167.6 mAh g-1 was achieved. In addition, a potassium-ion full cell is assembled by employing Fe1-xS as an anode and potassium Prussian blue as a cathode; it delivered a discharge capacity of 127.6 mAh g-1 at 100 mA g-1 after 50 cycles.
https://doi.org/10.1021/acsami.1c17799
Wafer-level fabrication of an EWOD-driven micropump. - In: MikroSystemTechnik, (2021), S. 574-577
Dimensioning and characterisation of an EWOD-driven chipintegrated micropump using time-resolved simulations. - In: MikroSystemTechnik, (2021), S. 531-534
Simulation model and dimensioning of a photoacoustic sensor for the detection of radiation-induced pressure surges. - In: MikroSystemTechnik, (2021), S. 523-526