Thin Bi2Se3 films were successfully electrodeposited from a non-aqueous ethylene glycol-based electrolyte and subsequently underwent thermal treatment in an Ar atmosphere to improve crystallinity. The phase and compositional properties of the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. XRD and Raman analyses confirmed the formation of crystalline rhombohedral Bi2Se3, while FTIR measurements indicated minor surface oxidation. The electrical and semiconductor properties of the films were investigated through current-voltage and temperature-dependent conductivity measurements. The activation energy associated with intrinsic conduction was determined to be 0.25 eV, while the temperature sensitivity coefficient and temperature coefficient of resistance were found to be 2903 K and 0.032-0.013 K-1, respectively. Infrared photoconductivity measurements in the wavelength range of 2800-4000 nm revealed a pronounced photoresponse near the band-gap energy of Bi2Se3. The obtained results demonstrate the potential of electrodeposited Bi2Se3 thin films for infrared-sensitive semiconductor and optoelectronic applications.
The practical deployment of aqueous zinc-ion batteries (AZIBs) is critically limited by uneven Zn2+ flux, uncontrolled dendrite growth, and concurrent parasitic reactions-notably the hydrogen evolution reaction (HER) and anode corrosion-arising from interfacial and kinetic instability during repeated plating/stripping cycles. These issues originate at the zinc anode-electrolyte interface, underscoring the necessity of advanced interfacial engineering. Here, we report a surface-confined polyphenol-derived interphase formed on zinc foil through a 1 min dip treatment in a dilute aqueous solution of a commercial tea polyphenol (TP) mixture (0.02 M); after rinsing and drying, the modified electrode is cycled in a conventional electrolyte to which no TP is deliberately added. This interphase promotes more homogeneous nucleation behaviour through coordination between phenolic oxygen-containing moieties and Zn2+, improves electrolyte contact homogeneity and perturbs the local water structure to mitigate water-mediated parasitic reactions. The TP-derived surface modification creates a substantially altered interfacial charging environment (Cdl = 47.25 vs. 16.83 µF cm-2 for bare Zn) that facilitates more uniform zinc deposition. Symmetric cells with TP@Zn anodes demonstrated exceptional cycling stability exceeding 4000 h at 1 mA cm-2 and 1 mAh cm-2 (bare Zn fails within ~240 h under identical conditions), while TP@Zn//V2O5 full cells retained 56.2% capacity after 300 cycles at 0.5 A g-1 with a higher median discharge voltage than bare Zn cells, substantially outperforming the latter (31.1% retention). Density functional theory calculations using the selected cluster models yield a markedly more negative electronic interaction energy for Zn2+ with an EGCG model ligand (-10.97 eV) than with H2O (-4.49 eV), qualitatively supporting preferential coordination of Zn2+ by phenolic oxygen sites. This work presents a green, facile and potentially scalable interfacial regulation strategy and advances the understanding of natural polyphenols as pre-formed surface conditioners for highly reversible metal anodes.
In this work, nanocrystalline high-entropy spinels with the nominal composition (Co,Mn,Ni,Cr,Fe)3O4 and different Fe contents were synthesized by a facile solution combustion method and evaluated as catalysts for the complete oxidation of light hydrocarbons and methanol decomposition. Structural characterization by XRD, SEM, TEM, XPS, Mössbauer spectroscopy, and N2 physisorption confirmed the formation of single-phase cubic spinels and mesoporous morphology. Increasing the Fe content resulted in changes in surface elemental distribution without altering the oxidation states of the cations. Among the investigated catalysts, HES-Fe 1:1 exhibited the highest specific surface area, favorable surface enrichment in Co and Mn, and the best catalytic performance for the complete oxidation of light hydrocarbons. In methanol decomposition, HES-Fe 1:1 showed the highest methanol conversion at lower temperatures, whereas HES-Fe 1:2 exhibited the highest CO selectivity, making it the most efficient catalyst for syngas production. The results establish a relationship between Fe content, surface composition, redox properties, and catalytic performance, revealing high-entropy spinels as promising catalysts for environmental catalysis and syngas production.
Grain boundaries (GBs) are important recombination-active defects in polycrystalline and multicrystalline silicon solar cells, but the effects of their electrical activity, geometry, and spatial arrangement are often difficult to separate. In this work, two-dimensional (2D) drift–diffusion simulations are used to investigate how GB trap density, carrier capture cross-section, orientation, length, number, and network geometry affect silicon solar-cell performance. A controlled comparison between rotating GBs whose length changes with angle and fixed-length GBs shows that the strong apparent orientation dependence is dominated by the accompanying variation in active GB length. When the GB length is fixed at 100 μm, the variations in short-circuit current density (Jsc), open-circuit voltage (Voc), efficiency, and fill factor are comparatively small. As a second contribution, irregular polycrystalline microstructures are generated by Voronoi tessellation, producing distributions of grain sizes, shapes, boundary lengths, and junctions that are more representative than simplified structures based on isolated or regularly spaced boundaries. These networks are used to connect grain size, total electrically active GB length, recombination, local electric fields, carrier-flow redistribution, and device performance. As the characteristic grain size increases from 5 to 100 μm, Jsc rises from 15 to 34mAcm−2, Voc from 0.54 to above 0.61 V, and the power conversion efficiency from 6.5% to 17%. GB-induced photovoltaic loss is therefore governed not by GB number or nominal orientation alone, but by the combined effects of electrical activity, total active boundary length, and network geometry.
