Potassium-ion batteries, due to their low cost and other advantages, are considered a complementary technology to lithium-ion batteries in the field of large-scale energy storage. In recent years, they have received widespread attention from researchers. Bismuth sulfide has been identified as a promising anode for potassium-ion batteries due to its high theoretical specific capacity and low cost. Nevertheless, the polysulfide shuttle and severe volumetric expansion severely plague its commercial application on a large scale. Herein, using SnCl₄ as the Sn source and employing a mixed surfactant of oleylamine/oleic acid with significant spatial steric hindrance, ultra-small Sn-doped Bi₂S₃ (Bi_1.9Sn_0.1S₃) nanorods were first prepared under hydrothermal conditions. Next, through the polymerization reaction of dopamine, a coating layer of approximately 5 nm thickness was formed on the surface of the nanorods. Finally, by ordered electrostatic self-assembly, PDDA-modified nanorods were combined with MXene to obtain PDA-coated Sn-doped Bi₂S₃/MXene (BSPM-20) composites for alkali metal-ion storage. The obtained nanocomposite displays a considerable reversible capacity of 599 mAh g⁻¹ at 0.1 A g⁻¹ and impressive cycling stability over 1000 cycles with a capacity decay of 0.007% per cycle. It also delivers a high reversible capacity of 756 mAh g⁻¹ for Li storage and 650 mAh g⁻¹ for Na storage at 0.1 A g⁻¹, respectively. In addition, we have revealed the mechanism of the dual confinement effect of PDA and MXene on Bi_1.9Sn_0.1S₃ through experiments and DFT calculations. At the same time, it has also been clarified through structural characterization and kinetic analysis that oleic acid/oleylamine, as a capping agent, reduces the scale of Bi_1.9Sn_0.1S₃ by inhibiting grain growth, thereby improving the kinetic rate of potassium storage reaction. This work provides ideas for solving the issues of long-term cycles of metal sulfide.

Nanoparticles (NPs) of titanium dioxide (TiO₂) have attracted a lot of attention as a potential photocatalyst for the degradation of pollutants, especially synthetic dyes like methyl orange, rhodamine B, and methylene blue (MB). Understanding the applicability of TiO2 nanoparticles in MB degradation requires emphasizing their unique physicochemical qualities, such as their large surface area, substantial oxidative potential, and outstanding chemical stability. The formation of reactive oxygen species (ROS) via photoinduced synthesis of electron–hole pairs under ultraviolet (UV) light irradiation is the central focus of a thorough investigation of the photocatalytic process of TiO₂. Through redox processes started by these electron–hole pairs exposed to solar light, TiO₂ aids in the breakdown of MB into less harmful byproducts in wastewater treatment. The important variables influencing photocatalytic performance are particle size, crystal phase (anatase, rutile, and brookite), surface modifications, and the addition of metal or non-metal dopants to enhance visible light absorption. The electron–hole pair separation make TiO₂ NPs feasible for photocatalysis, and this is possible for their large band gap, which was not in their bulk form. In the nano form, they have the same number of electrons as their bulk form but a large band gap at the semiconductor level. The main objective of this study is to fill knowledge gaps on TiO₂-based photocatalysis for MB degradation and suggest improvements to make these systems better for future wastewater treatment that is both efficient and sustainable.

The pursuit of eco-friendly and cost-effective photovoltaic (PV) technologies has driven significant interest in high-bandgap thin-film solar cells, such as kesterite, chalcopyrite, and perovskite materials [1]. Among them, Cu₂ZnSnS₄ (CZTS) stands out as a highly promising candidate due to its composition of Earth-abundant, non-toxic elements. CZTS combines an optimal bandgap with a high absorption coefficient, offering excellent optical and electronic properties that are ideal for single-junction and tandem solar cell applications [1]. Cu₂CdSnS₄ has emerged as a promising thin-film solar cell material, demonstrating excellent photovoltaic potential and device efficiency [2]. Cation substitution, particularly with Ag and Cd, is an effective strategy for enhancing Cu₂ZnSnS₄ solar cell performance. Ag reduces the open-circuit voltage deficit and defect density, and Ag substitution in Cu₂ZnSnS₄ reduces the open-circuit voltage deficit by limiting radiative and non-radiative recombination [2]. In this study, we investigate the structural, electronic, and optical properties of Ag-doped Cu₂ZnSnS₄ and Cu₂CdSnS₄ using density functional theory with a hybrid functional approach. Our primary objective is to understand how Ag substitution influences the lattice geometry, electronic bandgap, and optical absorption characteristics of these chalcogenide compounds. To gain deeper insights into the doping mechanisms, we analyze the electronic structure through the density of states (DOSs), partial DOSs (PDOSs), and electron density difference maps. Additionally, device-level simulations are conducted to assess the photovoltaic performance of Ag-doped materials, further evaluating their potential as efficient absorber layers in thin-film solar cells.

References

[1] A. Wang et al. Sustain. Energy Fuels 2021, 5, 1044−1058

[2] A Ibrahim, et al, Mater. Chem. A, 2024, 12, 2673

Titanium dioxide (TiO2) nanoparticles have garnered significant attention as a photocatalyst for degrading organic pollutants, particularly synthetic dyes such as rhodamine B (RhB), methylene blue, methyl orange, and others. The impact of several synthesis methods, including sol–gel, hydrothermal, and CVD techniques, on the electrical and morphological properties of TiO2 nanoparticles has been studied, emphasizing the distinctive physicochemical properties of TiO2 nanoparticles, including their extensive surface area, significant oxidative capacity, and remarkable chemical stability, which are important in addressing recent advancements in their use for RhB degradation. A detailed examination of TiO2's photocatalytic mechanism is based on the generation of reactive oxygen species (ROS) by photoinduced electron–hole pair formation under ultraviolet (UV) light exposure. In wastewater treatment, TiO2 degrades RhB into less harmful byproducts by the generation of electron–hole pairs that initiate redox reactions under sunlight. This study includes a thorough overview of significant factors influencing photocatalytic efficacy. The parameters include particle size, crystal phase (anatase, rutile, and brookite), surface changes, and the incorporation of metal or non-metal dopants to enhance visible light absorption. Researchers continually seek methods to overcome challenges, including restricted visible light responsiveness and rapid electron–hole recombination. The investigated approaches include heterojunction generation, composite development, and co-catalyst insertion. The primary objective of this work is to address the deficiencies in our understanding of TiO2-based photocatalysis for the degradation of RhB and to propose enhancements for these systems to enable more efficient and sustainable wastewater treatment in the future.

Photothermal catalysis, recognized as an efficient approach for solar-to-chemical conversion, enhances catalytic reactions more effectively under mild conditions. However, there are problems concerning low atomic utilization efficiency, poor intrinsic catalytic activity, and selectivity. Therefore, it is highly imperative that the development of photothermal catalysts with excellent activity, selectivity, and stability remains the key challenge in this field. Based on this, the rational design of highly efficient photothermal catalysts should satisfy three criteria: (1) excellent sunlight absorption ability, (2) effective thermal management to prevent heat dissipation, (3) great intrinsic reactivity for efficient catalytic performance, and (4) a special photochemistry effect. Confronted with this key challenge, our work primarily focuses on the construction of efficient photothermal catalysts. First, we have developed an ideal type of photothermal material (MXene) to enhance the photothermal catalytic performance. Second, we have designed a catalyst architecture that enables “supra-photothermal” CO₂ catalysis to reduce heat loss. Third, we developed efficient sunlight-driven MXene-supported metal cluster catalysts with sufficient metal dispersity and stability. Our work will provide guidance for the rational design of efficient photothermal CO₂ catalysts. Fourth, we report the discovery of anisotropic localized surface plasmon resonance (LSPR) in Ti3C2Tx MXene as well as site-selective photocatalysis enabled by the photophysical anisotropy. Both experimental and theoretical studies provide direct evidence of the occurrence of transverse and longitudinal dipolar plasmon resonance modes in the two-dimensional MXene nanoflakes.

Zinc oxide (ZnO) is widely used in antibacterial applications due to its excellent physicochemical properties and bioactivities. The incorporation of ZnO nanoparticles into polymers leads to the creation of nanocomposites with improved properties (e.g. optical, thermal, and biomedical properties). The aim of this work was to prepare and explore the properties of hybrid polymer/ZnO membranes. Two water-soluble copolymers, poly(N,N-dimethylacrylamide-co-2-(dimethylamino)ethyl methacrylate) (P(DMAM-co-DMAEMAx)) and poly(oligo(ethylene glycol methyl ether methacrylate)-co-glycidyl methacrylate) (P(PEGMA₅₀₀-co-GMAx)), were synthesized by free-radical copolymerization and subsequently combined to form cross-linked membranes through the reaction between the amine and epoxy groups derived from DMAEMA and GMA units, respectively. The successful cross-linking reaction was confirmed by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and the hybrid membranes were examined in terms of their swelling and weight-loss properties. ZnO nanoparticles ~7nm in size (found by Transmission Electron Microscopy) were prepared in boiled methanolic solution. The presence of ZnO in the membranes was confirmed by ATR-FTIR and X-ray diffraction (XRD) while the thermal properties were explored by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The surface wettability properties of pure and composite membranes were studied by measuring the contact angle, while their surface morphology was investigated by Scanning Electron Microscopy (SEM). In addition, photoluminescence spectroscopy was employed to compare the optical properties of the polymer/ZnO with the pure ZnO, to assess the possibility of exploiting these materials in optical applications.

Low-dimensional materials such as gallium phosphide (GaP) and gallium nitride (GaN) nanoribbons have attracted growing interest for thermoelectric energy conversion due to their size-dependent transport properties and favorable electronic structures. In this work, we utilize a first-principles computational framework that couples density functional theory (DFT) with the nonequilibrium Green’s function (NEGF) method to systematically investigate the charge and heat transport characteristics of GaP and GaN nanoribbons. Phonon dispersion analysis reveals distinct spectral gaps—estimated at 35 meV for GaP and 50 meV for GaN—between acoustic and optical modes, which play a pivotal role in suppressing lattice thermal conductivity. Our electronic transport simulations reveal pronounced quantum confinement, leading to discretized transmission channels and energy-selective transport. The thermoelectric response, characterized by Seebeck and Peltier coefficients, exhibits sign reversals and sharp peaks near the Fermi level, reflecting intricate interactions between electron and hole contributions. Projected density of states (PDOSs) further indicates that the electronic structure is strongly influenced by edge configuration and atomic arrangement. Under optimized conditions, the figure of merit (ZT) reaches values nearing 0.5-1, suggesting strong potential for integrating GaP and GaN nanoribbons into miniaturized thermoelectric systems. These findings provide valuable theoretical insights for guiding future experimental efforts toward efficient nanoscale energy-harvesting devices.

Enhancing the efficiency of thermoelectric materials relies heavily on reducing their lattice thermal conductivity. Since lowering the electronic contribution to heat transport negatively affects electrical performance, the focus shifts toward phonon engineering. Understanding phonon transport mechanisms is key to designing materials with reduced thermal conductivity using disorder and nanostructuring strategies.

We investigate phonon thermal transport in a silicon–germanium solid solution through classical molecular dynamics simulations coupled with harmonic lattice dynamics. Anharmonic effects, which are significant at elevated temperatures, are incorporated via the Green–Kubo approach to model lattice thermal conductivity. Additionally, phonon-projected density of states and mode-resolved mean free paths are analyzed.

The atomistic model accounts for mass contrast and random Ge substitution, enabling realistic disorder-induced phonon scattering. The vibrational spectra exhibit pronounced localization in high-frequency modes and broadening of spectral lines, indicating increased scattering. We observe that germanium atoms predominantly contribute to low-frequency phonon states, while silicon atoms dominate high-frequency dynamics. These effects collectively suppress heat transport by limiting phonon lifetimes and propagation lengths.

Our simulations demonstrate that introducing mass disorder and structural randomness leads to a substantial reduction in phonon-mediated heat conduction. This validates the approach of tuning phonon-scattering mechanisms as a practical route for improving thermoelectric performance. The results provide atomistic insight into how compositional disorder modifies vibrational behavior and thermal transport in SiGe-based alloys.

Introduction
Gold nanoparticles (GNPs) are known to enhance radiosensitization in cancer treatment, particularly in their immediate vicinity. This study examines the influence of the GNP size and dose rate on secondary electron production during the delivery of FLASH electron beams.

Methods
Using Geant4-DNA Monte Carlo simulation, GNPs with varying diameters (5, 10, 50, and 100 nm) were placed at the center of a 10 µm diameter water sphere. The Geant4 Livermore model was applied to the GNPs, while the Geant4 DNA-physics and -chemistry models were used for the water sphere. Electrons, with an energy of 1 MeV and ultra-high dose rates (UHDRs) of 60, 100, and 150 Gy/s, were directed from the GNPs' surfaces into the water sphere. Simulations continued until electron interactions with the GNPs and water sphere reached predefined dose values for each UHDR. The yield enhancement factor (YEF), defined as the ratio of secondary electrons with and without the GNP, was analyzed in relation to the GNP size and dose rate.

Results
YEFs within the water sphere increased with larger GNP diameters across all UHDRs. For example, at 60 Gy/s, YEFs rose from 1.022 for 5 nm GNPs to 1.081 for 100 nm GNPs. However, YEFs declined as the UHDR increased from 60 Gy/s to 150 Gy/s. Notably, at a UHDR of 60 Gy/s, the YEF near the 100 nm GNP center (2.75) was higher compared to the 5 nm GNP (1.73).

Conclusions
These preliminary findings suggest that larger GNPs combined with lower UHDRs yield higher secondary electron enhancement factors, providing valuable insights for optimizing GNP-enhanced FLASH radiotherapy.

Composite materials hold significant promise for advancing renewable energy storage solutions and enhancing efficiency. This study investigates the impact of reduced graphene oxide (rGO) on the structural and dielectric properties of K0.5Na0.5NbO3 (KNN). The samples were synthesized using both electrospinning and conventional solid-state methods. X-ray diffraction analysis confirmed the formation of a well-crystallized perovskite phase structure, with the incorporation of rGO reducing the crystallite size from 42.57 nm to 31.80 nm, indicating structural modifications. Rietveld refinement further corroborated the crystal structures of the ceramics, with chi-square χ2 values of 2.28 and 1.76 for KNN and KNN/rGO, respectively. Field emission scanning electron microscopy (FE-SEM) analysis revealed large grains, suggesting enhanced crystallinity or material aggregation due to rGO. The particle size distribution analysis indicated average sizes of 163.62 nm for KNN and 183.51 nm for KNN/rGO. Dielectric studies, conducted as a function of temperature and frequency, exhibited phase transitions, with an increased dielectric constant (ɛr) reaching 23,769 for KNN/rGO compared to 7,600 for KNN at 550 °C in the low-frequency region. The impedance diagrams for KNN and KNN/rGO displayed a typical semicircle response, indicating the presence of a grain/bulk effect in the material. The findings presented here demonstrate that rGO significantly enhances the structural and dielectric properties of KNN, rendering it a promising candidate for advanced energy applications.