This study presents a detailed investigation of Ni/Cu/Fe2O3:Bi2O3/n-GaN metal–oxide–semiconductor (MOS) heterojunctions, focusing on their structural, chemical, and electrical properties. Fe2O3:Bi2O3 composite films were successfully deposited on n-GaN substrates, as confirmed by glancing-angle X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), which verified the film’s crystallinity, composition, and the formation of a uniform insulating layer. XPS further confirmed the presence of key elements and proper interface formation between the metal electrodes and the semiconductor. Electrical measurements revealed that the MOS exhibited clear rectifying behavior with reduced leakage current compared to the conventional Schottky junction (SJ). Analysis of key parameters including Schottky barrier height (Φb), ideality factor (n), and series resistance (Rₛ) was conducted using multiple extraction methods (Cheung’s, F(V)–V, and ΨS–V), all showing good agreement. The forward I–V characteristics of both SJ and MOS HJs demonstrated ohmic behavior at lower voltage regions, transitioning to space-charge-limited conduction (SCLC) at higher voltages. This transition confirms the influence of interface states and trap-assisted conduction in determining the electrical transport mechanism. These results demonstrate the effectiveness of Fe2O3:Bi2O3 nanocomposites as insulating layers in GaN-based MOS devices and underscore their potential for future optoelectronic applications.
Zinc oxide nanoparticles (ZnO NPs) have already shown potential applications as antimicrobial agents. However, the large band gap and charge carrier recombination of ZnO NPs reduce the production of reactive oxygen species, which limits their antibacterial activity; therefore, further modifications of their structural and electronic properties are required. Herein, Cu doping of ZnO NPs has been carried out by a microwave-assisted method to modify their structural, electronic, and biological properties. The structural and morphological analysis of the prepared Cu-doped ZnO NPs confirmed that Cu is well incorporated into the ZnO NPs lattice, and the morphology is quasi-spherical with a diameter range of 20–25 nm. The changes in the band gap and defect states in ZnO NPs, formed upon Cu doping, were confirmed by UV-visible and theoretical analysis. The antimicrobial potential of ZnO and Cu-doped ZnO NPs against S. aureus, E. coli, P. aeruginosa, and C. albicans has been evaluated by measuring the zone of inhibition, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The results showed an enhancement of the antimicrobial potential of ZnO NPs upon Cu doping, which could be related to modifications of the electronic structure that could potentially affect redox properties.
A μ3-oxo-bridged trinuclear nickel(II) coordination cluster, [Ni3O(TDAD)6Cl3]Cl (TDAD = 1,3,4-thiadiazole-2,5-diamine), was synthesized and comprehensively characterized using complementary spectroscopic, structural, and physicochemical techniques. FT-IR and Raman spectroscopy confirmed coordination of TDAD through nitrogen donors and the presence of a robust Ni3O core, while UV-Vis-NIR data revealed ligand-centred and Ni(II) d-d transitions consistent with distorted octahedral geometry. Thermal analysis demonstrated multistep decomposition with the formation of a stable inorganic residue. SEM-EDS, elemental mapping, and XRF analyses verified homogeneous elemental distribution and phase purity, whereas PXRD confirmed crystallinity and consistency with the single-crystal structure. Single-crystal X-ray diffraction established a centrosymmetric hexagonal framework (space group P63/mcm) featuring vertex-sharing distorted octahedra around the Ni centres linked through the μ3-oxo bridge. Hirshfeld surface and fingerprint analyses highlighted dominant N–H···Cl hydrogen bonding supported by S- and van-der-Waals-type contacts in stabilizing the supramolecular packing. Antimicrobial evaluation demonstrated enhanced activity of the coordination cluster compared with the free ligand and nickel salt, producing inhibition zones of 18.0 ± 0.2 mm against Escherichia coli, 10.0 ± 0.1 mm against Bacillus subtilis, and 17.0 ± 0.1 mm against Candida albicans. Molecular docking calculations revealed favourable binding affinities (−6.3 to −8.1 kcal mol–1) and multiple stabilizing hydrogen-bonding and electrostatic interactions with microbial target proteins, supporting the experimental biological results. The combined structural, supramolecular, and biological findings indicate that μ3-oxo-bridged multinuclear nickel complexes incorporating thiadiazole ligands constitute promising candidates for further investigation as functional antimicrobial coordination materials.
Two zinc(II) coordination complexes, bis(4-aminobenzoate)bis(2-amino-5-methylthio-1,3,4-thiadiazole)zinc(II) [Zn(L)2(L1)2] (1) and bis(4-aminobenzoate)bis(2-amino-1,3,4-thiadiazole)zinc(II) monohydrate [Zn(L)2(L2)2] (2), were synthesized and structurally characterized. Single-crystal X-ray diffraction revealed tetrahedral Zn(II) coordination involving carboxylate and thiadiazole donors, stabilized by extensive hydrogen-bonding and it-it interactions. Hirshfeld surface analysis confirmed the predominance of C-H, N-H, and O-H contacts, with variations attributed to ligand substitution and hydration. Spectroscopic investigations, including FT-IR, Raman, and UV absorption, further validated coordination modes and highlighted electronic differences between the two systems. SEM-EDS analysis confirmed surface morphology and elemental composition, while XRF verified the absence of foreign elements, supporting high purity. Thermal studies indicated a three-step decomposition pattern in both complexes, finally yielding ZnO as the stable residue. The combined structural, spectroscopic, morphological, and thermal data emphasize the roles of ligand substitution and hydration in modulating supramolecular interactions, stability, and electronic properties. These findings provide valuable insights into the design of Zn(II)-based functional coordination compounds.
ABSTRACT Achieving efficient solar‐to‐hydrogen (STH) conversion is essential for renewable energy storage, yet solar‐driven water splitting remains fundamentally limited by energy losses associated with the anodic oxygen evolution reaction (OER). Herein, we deliberately combine Ir species with a NiFe model electrocatalyst to construct asymmetric Ir–O–Ni interfacial sites that optimize anodic reaction energetics. In situ spectroscopic analyses combined with theoretical calculations reveal that, in contrast to pristine NiFe operating via the conventional adsorbate evolution mechanism, the Ir–O–Ni interfacial sites directly participate in OER by lowering the *OOH deprotonation barrier and facilitating rapid proton transfer under alkaline conditions. Meanwhile, strong Ir–O orbital coupling stabilizes O‐containing intermediates, thereby reducing the O–O bond formation barrier from 3.21 eV in pristine NiFe to 1.40 eV in NiFe‐Ir. Consequently, NiFe‐Ir delivers a low overpotential of 300 mV at a high current density of 500 mA cm −2 , corresponding to a 43.3% reduction in energy consumption compared to NiFe (430 mV). Importantly, the substantially reduced anodic energy dissipation translates directly into enhanced device‐level performance, enabling the integrated photovoltaic‐electrolyzer system to achieve an exceptional STH conversion efficiency of 19.7%. These results underscore interfacial engineering as a powerful and generalizable strategy for advancing practical solar water‐splitting technologies.
