Surface-Enhanced Raman Spectroscopy and Artificial Neural Networks for Detection of MXene Flakes' Surface Terminations

The properties of MXene flakes, a new class of two-dimensional materials, are strictly determined by their surface termination. The most common termination groups are oxygen-containing (=O or -OH) and fluorine (-F), and their relative ratio is closely related to flake stability and catalytic activity. The surface termination can vary significantly among MXene flakes depending on the preparation route and is commonly determined after flake preparation by using X-ray photoelectron spectroscopy (XPS). In this paper, as an alternative approach, we propose the combination of surface-enhanced Raman spectroscopy (SERS) and artificial neural networks (ANN) for the precise and reliable determination of MXene flakes' (Ti3C2Tx) surface chemistry. Ti3C2Tx flakes were independently prepared by three scientific groups and subsequently measured using three different Raman spectrometers, employing resonant excitation wavelengths. Manual analysis of the SERS spectra did not enable accurate determination of the flake surface termination. However, the combined SERS-ANN approach allowed us to determine the surface termination with a high accuracy. The reliability of the method was verified by using a series of independently prepared samples. We also paid special attention to how the results of the SERS-ANN method are affected by the flake stability and differences in the conditions of flake preparation and Raman measurements. This way, we have developed a universal technique that is independent of the above-mentioned parameters, providing the results with accuracy similar to XPS, but enhanced in terms of analysis time and simplicity.

Decoding Niobium Carbide MXene Dual-Functional Photoactive Cathode in Photoenhanced Hybrid Zinc-Ion Capacitor

The coupling of energy harvesting and energy storage discrete modules in a single architecture as a "two-in-one" concept is significant in off-grid energy storage devices. This approach can decrease the device size and the loss of energy transmission in common integrated energy harvesting and storage systems. This work systematically investigates the photoactive characteristics of niobium carbide MXene, Nb2CTx, in a photoenhanced hybrid zinc-ion capacitor (P-ZIC). The unique configuration of the Nb2CTx photoactive cathode absorbs light to charge the capacitor and enables it to operate continuously in the light-powered mode. The Nb2CTx-based P-ZIC shows a photodriven capacitance enhancement of over 60% at the scan rate of 10 mV s-1 under 50 mW cm-2 illumination with 435 nm wavelength. Furthermore, a photoenhanced specific capacitance of ∼27 F g-1, an impressive photocharging voltage response of 1.0 V, and capacitance retention of ∼85% (over 3000 cycles) are obtained.

Tuning Germanane Band Gaps via Cyanoethyl Functionalization for Cutting-Edge Photoactive Cathodes: Photoenhanced Hybrid Zinc-Ion Capacitor Evaluation

Energy harvesting and storing by dual-functional photoenhanced (photo-E) energy storage devices are being developed to battle the current energy hassles. In this research work, our investigations on the photoinduced efficiency of germanane (Ge-H) and its functionalized analogue cyanoethyl (Ge-C2-CN) are assessed as photocathodes in photo-E hybrid zinc-ion capacitors (ZICs). The evaluated self-powered photodetector devices made by these germanene-based samples revealed effective performances in photogenerated electrons and holes. The photo-E ZICs findings provided a photoinduced capacitance enhancement of ∼52% (for Ge-H) and ∼26% (for Ge-C2-CN) at a scan rate of 10 mV s-1 under 100 mW cm-2 illumination with 435 nm wavelength. Further characterizations demonstrated that the photo-E ZIC with Ge-C2-CN supply higher specific capacitance (∼6000 mF g-1), energy density (∼550 mWh kg-1), and power density (∼31,000 mW kg-1), compared to the Ge-H. In addition, capacitance retention of photo-E ZIC with Ge-C2-CN is ∼91% after 3000 cycles which is almost 6% greater than Ge-H. Interestingly, the photocharging voltage response in photo-E ZIC made by Ge-C2-CN is 1000 mV, while the photocharging voltage response with Ge-H is approximately 970 mV. The observed performances in Ge-H-based photoactive cathodes highlight the pivotal role of such two-dimensional materials to be applied as single architecture in new unconventional energy storage systems. They are particularly noteworthy when compared to the other advanced photo-E supercapacitors and could even be enhanced greatly with other suitable inorganic and organic functional precursors.

Powering the Future: Unleashing the Potential of MXene-Based Dual-Functional Photoactive Cathodes in Photo-Rechargeable Zinc-Ion Capacitor

Dual-functional photo-rechargeable (photo-R) energy storage devices, which acquire stored energy from solar energy harvesting, are being developed to battle the current energy crisis. In this study, these findings on the photo-driven characteristics of MXene-based photocathodes in photo-R zinc-ion capacitors (ZICs) are presented. Along with the pristine Ti3 C2 Tx MXene, tellurium/Ti3 C2 Tx (Te/Ti3 C2 Tx ) hybrid nanostructure is synthesized via facile chemical vapor transport technique to examine them for photocathodes in ZICs. Interestingly, the evaluated self-powered photodetector devices using MXene-based samples revealed a pyro-phototronic behavior introduced into the samples, with higher desirability observed in Te/Ti3 C2 Tx . The photo-R ZICs results exhibited a capacitance enhancement of 50.86% for Te/Ti3 C2 Tx at two scan rates of 5 and 10 mV s-1 under illumination, compared to dark conditions. In contrast, a capacitance enhancement of 30.20% is obtained for the pristine Ti3 C2 Tx at only a 5 mV s-1 scan rate. Furthermore, both samples achieved photo-charging voltage responses of ≈960 mV, and photoconversion efficiencies of 0.01% (for Te/ Ti3 C2 Tx ) and 0.07% (for Ti3 C2 Tx ). These characteristics in MXene-based single photo-R ZICs are significant and considerable with the distinguished integrated photo-R supercapacitors with solar cells, or coupled energy-harvesting and energy-storing devices reported recently in the literature.

Two-Dimensional Van Der Waals Thin Film and Device

In the rapidly evolving field of thin-film electronics, the emergence of large-area flexible and wearable devices has been a significant milestone. Although organic semiconductor thin films, which can be manufactured through solution processing, have been identified, their utility is often undermined by their poor stability and low carrier mobility under ambient conditions. However, inorganic nanomaterials can be solution-processed and demonstrate outstanding intrinsic properties and structural stability. In particular, a series of two-dimensional (2D) nanosheet/nanoparticle materials have been shown to form stable colloids in their respective solvents. However, the integration of these 2D nanomaterials into continuous large-area thin with precise control of layer thickness and lattice orientation still remains a significant challenge. This review paper undertakes a detailed analysis of van der Waals thin films, derived from 2D materials, in the advancement of thin-film electronics and optoelectronic devices. The superior intrinsic properties and structural stability of inorganic nanomaterials are highlighted, which can be solution-processed and underscor the importance of solution-based processing, establishing it as a cornerstone strategy for scalable electronic and optoelectronic applications. A comprehensive exploration of the challenges and opportunities associated with the utilization of 2D materials for the next generation of thin-film electronics and optoelectronic devices is presented.

Atomic-layered V2C MXene containing bismuth elements: 2D/0D and 2D/2D nanoarchitectonics for hydrogen evolution and nitrogen reduction reaction

The exploitation of two-dimensional (2D) vanadium carbide (V₂CT_x, denoted as V₂C) in electrocatalytic hydrogen evolution reaction (HER) and nitrogen reduction reaction (NRR) is still in the stage of theoretical study with limited experimental exploration. Here, we present the experimental studies of V₂C MXene-based materials containing two different bismuth compounds to confirm the possibility of using V₂C as a potential electrocatalyst for HER and NRR. In this context, for the first time, we employed two different methods to synthesize 2D/0D and 2D/2D nanostructures. The 2D/2D V₂C/BVO consisted of BiVO₄ (denoted BVO) nanosheets wrapped in layers of V₂C which were synthesized by a facile hydrothermal method, whereas the 2D/0D V₂C/Bi consisted of spherical particles of Bi (Bi NPs) anchored on V₂C MXenes using the solid-state annealing method. The resultant V₂C/BVO catalyst was proven to be beneficial for HER in 0.5 M H₂SO₄ compared to pristine V₂C. We demonstrated that the 2D/2D V₂C/BVO structure can favor the higher specific surface area, exposure of more accessible catalytic active sites, and promote electron transfer which can be responsible for optimizing the HER activity. Moreover, V₂C/BVO has superior stability in an acidic environment. Whilst we observed that the 2D/0D V₂C/Bi could be highly efficient for electrocatalytic NRR purposes. Our results show that the ammonia (NH₃) production and faradaic efficiency (FE) of V₂C/Bi can reach 88.6 μg h^-1 cm^-2 and 8% at -0.5 V vs. RHE, respectively. Also V₂C/Bi exhibited excellent long-term stability. These achievements present a high performance in terms of the highest generated NH₃ compared to recent investigations of MXenes-based electrocatalysts. Such excellent NRR of V₂C/Bi activity can be attributed to the effective suppression of HER which is the main competitive reaction of the NRR.

Development of an object-specific remediation solution for the waste rock dumps at the formerly abandoned Wismut sites

The investigation of the radiation situation is an essential part of preparing the remediation of the formerly abandoned Wismut sites. If the exposure is relevant, then the exposure pathway “inhalation of radon/radon daughters” plays the dominant role. Therefore, the development of a straightforward approach suitable for the evaluation of the involved radon situation is one of the most important tasks. It has to include the whole chain beginning with the characterization of the relevant exposure situation and ending up with the identification of remedial options. For that purpose a new technique of visualizing the radon flux from the waste rock dumps has been developed. The specific conditions at formerly abandoned Wismut sites will be demonstrated and the remediation solutions envisaged to reduce the radon flux will be explained.

Application of the tracer gas technology to investigate convective radon transport processes between mine workings and houses

In areas featuring air-filled mine workings the convective radon transport through the disturbed bedrock is a frequent cause of high radon concentrations in dwellings. The vertical transport distance of the radon propagation can be more than one hundred meters. The application of tracer gases that can be detected by gas chromatography at extreme low concentrations allows the clear detection of mine-originated radon in dwellings and provides knowledge on the complex processes of radon transport. The successful application of the method is demonstrated on the basis of investigations of the impact of former uranium mine sites on the radon situation in dwellings.

Disease status in patients with chronic myeloid leukemia is better characterized by BCR-ABL/BCR transcript ratio than by BCR-ABL transcript level, which may suggest a role of normal BCR gene in the disease pathogenesis

Monitoring of BCR-ABL transcript level is widely used in chronic myeloid leukemia (CML) to follow up response to therapy. In this study we compare abilities of two quantitative RT-PCR assays to characterize the disease status in CML patients: RT-PCR quantifying the BCR-ABL transcript concentration and RT-PCR determining the BCR-ABL/BCR transcript ratio (R). We demonstrate that in non-responders only R, but not BCR-ABL, unambiguously characterizes the state of disease. Moreover, R values >1 found in all poor responders indicate lower BCR expression compared to BCR- ABL in these patients. Our results demonstrate the importance of BCR-ABL/BCR transcript ratio for the disease status and the disease prognosis characterization and suggest a possible role of the normal BCR gene expression in CML pathogenesis.

Innovations in integrated dual diagnosis treatment in public managed care: the Choate dual diagnosis case rate program

This article describes the implementation and preliminary evaluation of a dual diagnosis case rate program developed as a collaborative experiment between a public managed Medicaid organization (MHMA) and a specialized integrated dual diagnosis provider (Choate) with a vertically integrated, managed-care oriented system of care. The case rate program applied to dually-diagnosed inpatient referrals for a period of 65 days. On admission, 68% of the patients had little insight, motivation and compliance regarding addiction or psychiatric management. Nonetheless, 56% maintained sobriety for 65 days, and 49% of these were still sober at 95-day follow up.