Improving silicon photocathode performance for water reduction through dual interface engineering and integrating ReS2 photocatalyst. - In: ACS applied energy materials, ISSN 2574-0962, Bd. 5 (2022), 7, S. 8222-8231
Photoelectrochemical (PEC) water splitting for H2 production is a possible alternative for fossil energy in the future. However, there exists three problems in PEC water splitting with the silicon (Si) photocathode: poor light absorption of the untreated Si substrate, bad stability in strong acid solution, and poor photocatalytic activity of Si. Here, a strategy of dual interface engineering and photocatalyst deposition is proposed to improve the PEC performance, which consists of fabricating black Si (b-Si) by reactive ion etching, depositing of TiO2 on the b-Si by atomic layer deposition, and growing ReS2 on top of the TiO2 by chemical vapor deposition. Owing to the suitable band alignment of b-Si, TiO2, and ReS2, the ReS2/TiO2/b-Si shows obviously enhanced PEC performance compared to b-Si, TiO2/b-Si, and ReS2/b-Si photocathodes. Results of electrochemical impedance spectroscopy and Mott-Schottky plot analysis demonstrate that the TiO2 layer plays an important role and the charge-transfer kinetics of the system is clearly improved. Transient photocurrent measurements indicate that the ReS2/TiO2/b-Si photocathode has the most remarkable photocurrent response. In addition, the ReS2/TiO2/b-Si photocathode also shows excellent stability after being operated for 25 h.
https://doi.org/10.1021/acsaem.2c00761
Further dimensions for sensing in biofluids: distinguishing bioorganic analytes by the salt-induced adaptation of a cucurbit[7]uril-based chemosensor. - In: Journal of the American Chemical Society, ISSN 1520-5126, Bd. 144 (2022), 29, S. 13084-13095
Insufficient binding selectivity of chemosensors often renders biorelevant metabolites indistinguishable by the widely used indicator displacement assay. Array-based chemosensing methods are a common workaround but require additional effort for synthesizing a chemosensor library and setting up a sensing array. Moreover, it can be very challenging to tune the inherent binding preference of macrocyclic systems such as cucurbit[n]urils (CBn) by synthetic means. Using a novel cucurbit[7]uril-dye conjugate that undergoes salt-induced adaptation, we now succeeded in distinguishing 14 bioorganic analytes from each other through the facile stepwise addition of salts. The salt-specific concentration-resolved emission provides additional information about the system at a low synthetic effort. We present a data-driven approach to translate the human-visible curve differences into intuitive pairwise difference measures. Ion mobility experiments combined with density functional theory calculations gave further insights into the binding mechanism and uncovered an unprecedented ternary complex geometry for CB7. TThis work introduces the non-selectively binding, salt-adaptive cucurbit[n]uril system for sensing applications in biofluids such as urine, saliva, and blood serum.
https://doi.org/10.1021/jacs.2c01520
Analysis of TRWP particle distribution in urban and suburban landscapes, connecting real road measurements with particle distribution simulation. - In: Atmosphere, ISSN 2073-4433, Bd. 13 (2022), 8, 1204, S. 1-17
This article deals with methods and measurements related to environmental pollution and analysis of particle distribution in urban and suburban landscapes. Therefore, an already-invented sampling method for tyre road wear particles (TRWP) was used to capture online emission factors from the road. The collected particles were analysed according to their size distribution, for use as an input for particle distribution simulations. The simulation model was a main traffic intersection, because of the high vehicle dynamic related to the high density of start-stop manoeuvres. To compare the simulation results (particle mass (PM) and particle number (PN)) with real-world emissions, measuring points were defined and analysed over a measuring time of 8 h during the day. Afterwards, the collected particles were analysed in terms of particle shape, appearance and chemical composition, to identify the distribution and their place of origin. As a result of the investigation, the appearance of the particles showed a good correlation to the vehicle dynamics, even though there were a lot of background influences, e.g., resuspension of dust. Air humidity also showed a great influence on the recorded particle measurements. In areas of high vehicle dynamics, such as heavy braking or accelerating, more tyre and brake particles could be found.
https://doi.org/10.3390/atmos13081204
Measurement precision of a planar nanopositioning machine with a range of motion of Ø100 mm. - In: Applied Sciences, ISSN 2076-3417, Bd. 12 (2022), 15, 7843, S. 1-14
This work deals with various investigations into the accuracy of a newly developed planar nanopositioning machine. This machine, called Nanofabrication Machine 100 (NFM-100), has a positioning range of 100 mm in diameter. To determine the precision, various movement scenarios are performed with the machine table, and the trajectory deviation from the set trajectory is determined. In particular, the focus is on high velocities of up to 20 mm/s. Even at high speeds in the range of several millimetres per second, this machine can impress with its performance and only has a deviation in the nanometre range.
https://doi.org/10.3390/app12157843
Four-level structural hierarchy: microfluidically supported synthesis of polymer particle architectures incorporating fluorescence-labeled components and metal nanoparticles. - In: Langmuir, ISSN 1520-5827, Bd. 38 (2022), 29, S. 8794-8804
Hierarchical assemblies of functional polymer particles are promising due to their surface as well as physicochemical properties. However, hierarchical composites are complex and challenging to form due to the many steps necessary for integrating different components into one system. Highly structured four-level composite particles were formed in a four-step process. First of all, gold (Au) nanoparticles, poly(methyl methacrylate) (PMMA) nanoparticles, and poly(tripropylene glycol diacrylate) (poly-TPGDA) microparticles were individually synthesized. By applying microfluidic techniques, polymer nano- and microparticles were formed with tunable size and surface properties. Afterwards, the negatively charged gold nanoparticles and PMMA particles functionalized with a positively charged surface were mixed to form Au/PMMA assemblies. The Au/PMMA composites were mixed and incubated with poly-TPGDA microparticles to form ternary Au/PMMA/poly-TPGDA assemblies. For the formation of composite-containing microparticles, Au/PMMA/poly-TPGDA composites were dispersed in an aqueous acrylamide-methylenebisacrylamide solution. Monomer droplets were formed in a co-flow microfluidic device and photopolymerized by UV light. In this way, hierarchically structured four-level composites consisting of four different size ranges - 0.025/0.8/30/1000 μm - were obtained. By functionalizing polymer nano- and microparticles with different fluorescent dyes, it was possible to visualize the same composite particle under two different excitation modes (λex = 395-440 and λex = 510-560 nm). The Au/PMMA/poly-TPGDA composite-embedded polyacrylamide microparticles can be potentially used as a model for the creation of composite particles for sensing, catalysis, multilabeling, and biomedical applications.
https://doi.org/10.1021/acs.langmuir.2c00686
Modified polydopamine derivatives as high-performance organic anodes for potassium-ion batteries. - In: Sustainable energy & fuels, ISSN 2398-4902, Bd. 6 (2022), 15, S. 3527-3535
Polydopamine (PDA) as a carbon source and a versatile coating material has been widely studied in rechargeable battery electrodes. However, it is rare to directly utilize PDA as an organic anode for ion storage, especially in potassium-ion batteries (PIBs). In this work, modified PDA (MPDA-350) with a porous structure is synthesized by collective methods of template-assisted and low-temperature pyrolysis, which endows PDA with large ion diffusion tunnels and increased active sites for K+ ion storage. Moreover, contrast experiments demonstrate that the annealing process with an appropriate temperature can increase the content and activity of electroactive groups in MPDA-350. The prepared MPDA-350 is first applied to PIBs that deliver high reversible capacity (384.9 mA h g^-1 at 100 mA g^-1) and very stable cyclability (99.94% capacity retention after 500 cycles). This work provides a new insight for the expansion of high-performance organic anodes for PIBs.
https://doi.org/10.1039/D2SE00684G
Three-dimensional heating and patterning dynamics of particles in microscale acoustic tweezers. - In: Lab on a chip, ISSN 1473-0189, Bd. 22 (2022), 15, S. 2886-2901
Acoustic tweezers facilitate a noninvasive, contactless, and label-free method for the precise manipulation of micro objects, including biological cells. Although cells are exposed to mechanical and thermal stress, acoustic tweezers are usually considered as biocompatible. Here, we present a holistic experimental approach to reveal the correlation between acoustic fields, acoustophoretic motion and heating effects of particles induced by an acoustic tweezer setup. The system is based on surface acoustic waves and was characterized by applying laser Doppler vibrometry, astigmatism particle tracking velocimetry and luminescence lifetime imaging. In situ measurements with high spatial and temporal resolution reveal a three-dimensional particle patterning coinciding with the experimentally assisted numerical result of the acoustic radiation force distribution. In addition, a considerable and rapid heating up to 55 ˚C depending on specific parameters was observed. Although these temperatures may be harmful to living cells, counter-measures can be found as the time scales of patterning and heating are shown to be different.
https://doi.org/10.1039/D2LC00200K
Fabrication of long-life quasi-solid-state Na-CO2 battery by formation of Na2C2O4 discharge product. - In: Cell reports, ISSN 2666-3864, Bd. 3 (2022), 7, 100973, S. 1-15
Rechargeable Na-CO2 batteries are promising energy-storage devices due to their high energy density, environmental friendliness, and cost effectiveness. However, the insulating nature and irreversibility of the Na2CO3 discharge product cause large polarization and poor cyclicity. Here, we report a reversible quasi-solid-state Na-CO2 battery that is constructed by the synergistic action of a Co-encapsulated N-doped carbon framework catalyst and gel electrolyte to ensure the formation of a highly reversible Na2C2O4 discharge product. Experiments and density functional theory calculations indicate that the electron-agglomeration effect of Co nanoparticles enhances CO2 adsorption and lowers energy barrier, as well as promotes Na2C2O4 generation. A gel electrolyte containing an imidazole organic cation is used to inhibit the decomposition of the thermodynamically unstable Na2C2O4. The fabricated Na-CO2 battery exhibits a high discharge capacity of 3,094 mAh g^-1, a high-rate performance of 1,777 mAh g^-1 at a current density of 0.5 mA cm^-2, and excellent cycling performance of 366 cycles (2,200 h).
https://doi.org/10.1016/j.xcrp.2022.100973
Synthesis of CoSe2 reinforced nitrogen-doped carbon composites as advanced anodes for potassium-ion batteries. - In: Inorganic chemistry frontiers, ISSN 2052-1553, Bd. 9 (2022), 15, S. 3719-3727
Potassium-ion batteries (PIBs) are considered potential candidates for large-scale energy storage applications with cost superiority. However, the development of PIBs is severely restricted by the sluggish electrochemical kinetics and severe volume expansion of anode materials. Herein, CoSe2 reinforced nitrogen-doped carbon composites (CoSe2C) are synthesized via a simple solution-based etching-coating method and further studied as high-performance anodes for PIBs. Electrochemical characterization studies indicate that the potassium storage performance of CoSe2@C composite anodes relies on the initial mass ratio of CoSe2 nanosheets and carbon precursors (that is dopamine hydrochloride) during the synthesis process. In the case of the mass ratio of CoSe2 nanosheets and dopamine hydrochloride being 1 : 1, the as-obtained CoSe2@C-1 : 1 anode exhibits a high reversible capacity (366.1 mA h g^-1 at 0.1 A g^-1 after 100 cycles), an excellent long-cycle stability (237.6 mA h g^-1 at 1.0 A g^-1 after 1000 cycles), and a good rate capability (281.5 mA h g^-1 at 5.0 A g^-1). The optimum performance of CoSe2@C-1 : 1 as a PIB anode in terms of cycling stability and kinetics is attributed to the uniform distribution of CoSe2 nanoparticles inside the carbon matrix.
https://doi.org/10.1039/D2QI00848C
Artificial neural network performance based on correlation analysis qualitatively comparable with human performance in behavioral signal detection experiments. - In: Journal of neurophysiology, ISSN 1522-1598, Bd. 128 (2022), 2, S. 279-289
Standard Gaussian signal detection theory (SDT) is a widely used approach to assess the detection performance of living organisms or technical systems without looking at the inner workings of these systems like neural or electronic mechanisms. Nevertheless, a consideration of the inner mechanisms of a system and how they produce observed behaviors should help to better understand the functioning. It might even offer the possibility to demonstrate isolated pattern separation processes directly in the model. To do so, modeling the interaction between the entorhinal cortex (EC) and the hippocampal subnetwork dentate gyrus (DG) via the perforant path reveals the decorrelation network’s mode of operation. We show that the ability to do pattern separation is crucial for high-performance pattern recognition, but also for lure discrimination, and depends on the proportionality between input and output network.
https://doi.org/10.1152/jn.00393.2021