Infrared light dual excitation of Ni-phytate-sensitized ZnIn2S4 with sulfur vacancies for enhanced NIR-driven photocatalysis. - In: Chemical communications, ISSN 1364-548X, Bd. 60 (2024), 8, S. 1035-1038
Near-infrared (NIR) light accounts for about half of the solar spectrum, and the effective utilization of low-energy NIR light is an important but challenging task in the field of photocatalysis. Molecular semiconductor photocatalytic systems (MSPSs) are highly tunable, available and stable, and are considered to be one of the most promising ways to achieve efficient NIR hydrogen production. Here, we demonstrate efficient dual-excitation in MSPS consisting of ZnIn2S4−x (ZIS1−x) with sulfur vacancies and phytic acid nickel (PA-Ni), which differs from other NIR-responsive photosensitized systems. The system achieves a hydrogen evolution reaction (HER) of 119.85 μmol h−1 g−1 at λ > 800 nm illumination, which is an excellent performance among all reported NIR catalysts and even outperforms the noble metal catalysts when compared to the reported literature. The superior activity is attributed to the unique charge dynamics and higher carrier concentration of the system. This work demonstrates the potential of dual-excitation systems for efficient utilization of low-energy NIR light.
https://doi.org/10.1039/D3CC05089K
Ordered anodic aluminum oxide-based nanostructures for surface-enhanced Raman scattering: a review. - In: ACS applied nano materials, ISSN 2574-0970, Bd. 7 (2024), 1, S. 11-31
As a promising spectroscopic technique, surface enhanced raman spectroscopy (SERS) has been intensively used in bio/chemical sensing, attributing to its unique advantages of ultrasensitive and accurate detection of trace amounts of analytes, high specific fingerprint-like features, fast response, and noninvasive sensing. The robustness and consistency of SERS signals in practical analytical applications highly rely on the composition, structural morphology, and uniformity of SERS substrates. These factors play a pivotal role in determining the intensity and reproducibility of the detected signals. SERS substrates based on ordered nanostructures that are fabricated from anodic aluminum oxide (AAO)-template-assisted approaches are of significant interest due to their cost effectiveness, scalability, precise structural control, and exceptionally ordered features. In this review, recent progress in SERS substrates with high sensitivity and reproducibility prepared from AAO templates is highlighted. We emphasize the optimization strategies toward achieving efficient SERS-active substrates by fine-tuning the size, composition, and morphology of AAO-derived ordered nanostructures. Furthermore, we delve into the discussion of flexible and smart SERS substrates, while also exploring key aspects pertinent to further amplifying SERS signals. Overall, this review aims to offer insights into the future integration of the AAO templates technique with SERS, providing crucial perspectives for forthcoming research in this field.
https://doi.org/10.1021/acsanm.3c04652
Efficient analytical evaluation of the singular BEM integrals for the three-dimensional Laplace and Stokes equations over polygonal elements. - In: Engineering analysis with boundary elements, ISSN 0955-7997, Bd. 161 (2024), S. 70-77
Singularities in the fundamental solutions pose a mathematical challenge for all applications of the boundary element method, if the source and field point lie on the same element. To avoid complex and error-prone numerical procedures, analytical solutions for the integrals that arise are desirable. In this work, easy and efficiently to implement analytical solutions are presented for the fundamental solutions of the three-dimensional Stokes equation as well as Laplace’s equation. Explicit expressions are derived for general triangular elements using constant shape functions. In addition, options for extending to arbitrary polygonal elements are shown. In particular, the three cases that the incenter, the centroid or the vertices of the triangles are used as source points for the calculation are addressed. The impressive numerical efficiency of the method is demonstrated by explicit examples.
https://doi.org/10.1016/j.enganabound.2024.01.013
Insights into nano- and micro-structured scaffolds for advanced electrochemical energy storage. - In: Nano-Micro letters, ISSN 2150-5551, Bd. 16 (2024), 1, 130, S. 1-44
Adopting a nano- and micro-structuring approach to fully unleashing the genuine potential of electrode active material benefits in-depth understandings and research progress toward higher energy density electrochemical energy storage devices at all technology readiness levels. Due to various challenging issues, especially limited stability, nano- and micro-structured (NMS) electrodes undergo fast electrochemical performance degradation. The emerging NMS scaffold design is a pivotal aspect of many electrodes as it endows them with both robustness and electrochemical performance enhancement, even though it only occupies complementary and facilitating components for the main mechanism. However, extensive efforts are urgently needed toward optimizing the stereoscopic geometrical design of NMS scaffolds to minimize the volume ratio and maximize their functionality to fulfill the ever-increasing dependency and desire for energy power source supplies. This review will aim at highlighting these NMS scaffold design strategies, summarizing their corresponding strengths and challenges, and thereby outlining the potential solutions to resolve these challenges, design principles, and key perspectives for future research in this field. Therefore, this review will be one of the earliest reviews from this viewpoint.
https://doi.org/10.1007/s40820-024-01341-4
Enhancing the performance of quantum reservoir computing and solving the time-complexity problem by artificial memory restriction. - In: Physical review research, ISSN 2643-1564, Bd. 6 (2024), 1, 013051, S. 013051-1-013051-11
We propose a scheme that can enhance the performance and reduce the computational cost of quantum reservoir computing. Quantum reservoir computing is a computing approach which aims at utilizing the complexity and high dimensionality of small quantum systems, together with the fast trainability of reservoir computing, in order to solve complex tasks. The suitability of quantum reservoir computing for solving temporal tasks is hindered by the collapse of the quantum system when measurements are made. This leads to the erasure of the memory of the reservoir. Hence, for every output, the entire input signal is needed to reinitialize the reservoir, leading to quadratic time complexity. Another critical issue for the hardware implementation of quantum reservoir computing is the need for an experimentally accessible means of tuning the nonlinearity of the quantum reservoir. We present an approach which addresses both of these issues. We propose artificially restricting the memory of the quantum reservoir by only using a small number inputs to reinitialize the reservoir after measurements are performed. This strongly influences the nonlinearity of the reservoir response due to the influence of the initial reservoir state, while also substantially reducing the number of quantum operations needed to perform time-series prediction tasks due to the linear rather than quadratic time complexity. The reinitialization length therefore provides an experimental accessible means of tuning the nonlinearity of the response of the reservoir, which can lead to significant task-specific performance improvement. We numerically study the linear and quadratic algorithms for a fully connected transverse Ising model and a quantum processor model.
https://doi.org/10.1103/PhysRevResearch.6.013051
Research progress on vanadium sulfide anode materials for sodium and potassium-ion batteries. - In: Advanced Materials Technologies, ISSN 2365-709X, Bd. n/a (2024), n/a, 2301840, S. 1-28
Considering environmental changes and the demand for more sustainable energy sources, stricter requirements have been placed on electrode materials for sodium and potassium-ion batteries, which are expected to provide higher energy and power density while being affordable and sustainable. Vanadium sulfide-based materials have emerged as intriguing contenders for the next generation of anode materials due to their high theoretical capacity, abundant reserves, and cost-effectiveness. Despite these advantages, challenges such as limited cycle life and restricted ion diffusion coefficients continue to impede their effective application in sodium and potassium-ion batteries. To overcome the limitations associated with electrochemical performance and circumvent bottlenecks imposed by the inherent properties of materials at the bulk scale, this review comprehensively summarizes and analyzes the crystal structures, modification strategies, and energy storage processes of vanadium sulfide-based electrode materials for sodium and potassium-ion batteries. The objective is to guide the development of high-performance vanadium-based sulfide electrode materials with refined morphologies and/or structures, employing environmentally friendly and cost-efficient methods. Finally, future perspectives and research suggestions for vanadium sulfide-based materials are presented to propel practical applications forward.
https://doi.org/10.1002/admt.202301840
Impact of the tip-to-semiconductor contact in the electrical characterization of nanowires. - In: ACS omega, ISSN 2470-1343, Bd. 9 (2024), 5, S. 5788-5797
Well-defined semiconductor heterostructures are a basic requirement for the development of high-performance optoelectronic devices. In order to achieve the desired properties, a thorough study of the electrical behavior with a suitable spatial resolution is essential. For this, various sophisticated tip-based methods can be employed, such as conductive atomic force microscopy or multitip scanning tunneling microscopy (MT-STM). We demonstrate that in any tip-based measurement method, the tip-to-semiconductor contact is decisive for reliable and precise measurements and in interpreting the properties of the sample. For that, we used our ultrahigh-vacuum-based MT-STM coupled in vacuo to a reactor for the preparation of nanowires (NWs) with metal organic vapor phase epitaxy, and operated our MT-STM as a four-point nanoprober on III-V semiconductor NW heterostructures. We investigated a variety of upright, free-standing NWs with axial as well as coaxial heterostructures on the growth substrates. Our investigation reveals charging currents at the interface between the measuring tip and the semiconductor via native insulating oxide layers, which act as a metal-insulator-semiconductor capacitor with charging and discharging conditions in the operating voltage range. We analyze in detail the observed I-V characteristics and propose a strategy to achieve an optimized tip-to-semiconductor junction, which includes the influence of the native oxide layer on the overall electrical measurements. Our advanced experimental procedure enables a direct relation between the tip-to-NW junction and the electronic properties of as-grown (co)axial NWs providing precise guidance for all future tip-based investigations.
https://doi.org/10.1021/acsomega.3c08729
Multi-strategy coordination enables WSe2 to achieve high-performance real-world detection of NO2. - In: Sensors and actuators, ISSN 0925-4005, Bd. 403 (2024), 135183, S. 1-10
In recent years, WSe2 has become an ideal material for room-temperature NO2 gas sensing, but its low response and long response time limit its application. In this study, we combined multiple strategies of constructing a three-dimensional structure, introducing Se vacancies, Au nanoparticle sensitization, and 1 T/2 H-phase modulation. The synergistic effect was utilized to effectively enhance the gas adsorption, charge transfer degree, and carrier transport capacity of WSe2 and achieve high-performance NO2 detection. The prepared V-WAAP achieved high response (78.32%) with a short response time (33 s), and outstanding stability and selectivity for low concentration (1 ppm) NO2. The intrinsic factors of sensing performance improvement were comprehensively analyzed by combining the results of compositional and structural characterization. In addition, we verified its potential for practical applications by assembling a V-WAAP-based NO2 gas sensing equipment.
https://doi.org/10.1016/j.snb.2023.135183
Research progress of transition metal compounds as bifunctional catalysts for zinc-air batteries. - In: Nano research energy, ISSN 2790-8119, Bd. 3 (2024), 1, e9120092, S. 1-23
Zinc-air batteries (ZABs) are widely studied because of their high theoretical energy density, high battery voltage, environmental protection, and low price. However, the slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the air electrode limits the further application of ZABs, so that how to develop a cheap, efficient, and stable catalyst with bifunctional catalytic activity is the key to solving the development of ZABs. Transition metal compounds are widely used as cathode materials for ZABs due to their low cost, high electrocatalytic activity, and stable structure. This review summarizes the research progress of transition metal compounds as bifunctional catalysts for ZABs. The development history, operation principle, and mechanism of ORR and OER reactions are introduced first. The application and development of transition metal compounds as bifunctional catalysts for ZABs in recent years are systematically introduced, including transition metal oxides (TMOs), transition metal nitrides (TMNs), transition metal sulfides (TMSs), transition metal carbides (TMCs), transition metal phosphates (TMPs), and others. In addition, the shortcomings of transition metal compounds as bifunctional catalysts for ZABs were summarized and reasonable design strategies and improvement measures were put forward, aiming at providing a reference for the design and construction of high-performance ZABs cathode materials. Finally, the challenges and future in this field are discussed and prospected.
https://doi.org/10.26599/NRE.2023.9120092
Dissociation of singlet excitons dominates photocurrent improvement in high-efficiency non-fullerene organic solar cells. - In: Nano research energy, ISSN 2790-8119, Bd. 3 (2024), 1, e9120099, S. 1-8
In organic solar cells, the singlet and triplet excitons dissociate into free charge carriers with different mechanisms due to their opposite spin state. Therefore, the ratio of the singlet and triplet excitons directly affects the photocurrent. Many methods were used to optimize the performance of the low-efficiency solar cell by improving the ratio of triplet excitons, which shows a long diffusion length. Here we observed that in high-efficiency systems, the proportion of singlet excitons under linearly polarized light excitation is higher than that of circularly polarized light. Since the singlet charge transfer state has lower binding energy than the triplet state, it makes a significant contribution to the charge carrier generation and enhancement of the photocurrent. Further, the positive magnetic field effect reflects that singlet excitons dissociation plays a major role in the photocurrent, which is opposite to the case of low-efficiency devices where triplet excitons dominate the photocurrent.
https://doi.org/10.26599/NRE.2023.9120099