Dalton Transactions最新文献

The present work reports the preparation of ruthenium (0, 1, 3 and 5 wt%)-doped indium oxide thin films using the nebulizer spray pyrolysis (NSP) technique and the characterization of their physical properties. The novelty of this work lies in the systematic Ru-concentration-dependent defect engineering of In₂O₃ thin films, in which the synergistic effects of Ru-induced catalytic activation, oxygen-vacancy-related defect states, and interfacial charge transfer are optimized to achieve enhanced room-temperature NH₃ sensing. XRD analysis confirmed the cubic bixbyite structure with a slight increase in crystallite size upon Ru doping, suggesting the successful incorporation of Ru ions into the In₂O₃ lattice. UV-vis analysis confirmed the presence of a direct band gap with a small redshift attributed to Ru-induced defect states. FESEM images showed increased surface roughness and porosity upon doping, which are beneficial for gas adsorption. XPS measurements verified the incorporation of Ru into the In₂O₃ matrix. Photoluminescence spectra showed enhanced charge separation and an increase in oxygen-vacancy concentration at the optimum Ru concentration of 3 wt%. Gas sensing studies revealed that the 3 wt% Ru-doped In₂O₃ thin film exhibits an excellent response toward NH₃ at room temperature, with a maximum response of 1140 for 250 ppm NH₃, along with response and recovery times of 17.3 s and 20.1 s, respectively. The sensing measurements were carried out in a controlled chamber using calibrated NH₃ concentrations, and the reported values represent averaged results from multiple sensing cycles, ensuring good reproducibility and reliability. The improved sensing performance is attributed to the catalytic effect of Ru, defect-state-driven adsorption sites, and optimized surface morphology. The sensor also exhibited excellent selectivity, reproducibility, stability, and enhanced gas response under humid conditions. These findings demonstrate that Ru-doped In₂O₃ thin films are promising candidates for high-performance room-temperature ammonia gas sensors.

Oxypyriporphyrin (OxyPyP) possesses an unusually expanded N₄ coordination cavity, yet its influence on the electronic structures of coordinated metal ions remains poorly understood. Herein, we investigate a series of OxyPyHEP-Fe(III) complexes with different axial-ligation environments to clarify how the expanded coordination cavity influences their structures and spin states. Among these complexes, the six-coordinate complex [OxyPyHEPFe(III)(1-MeIm)(Cl)] (2), bearing 1-methylimidazole (1-MeIm) and chloride as axial ligands, was isolated and structurally characterized. 2 features a mixed neutral/anionic axial-ligation environment. Single-crystal X-ray diffraction analysis reveals an expanded N₄ cavity (8.738 Ų) with elongated Fe-N(1-MeIm) (2.181 Å) and Fe-Cl (2.354 Å) bonds. Magnetic susceptibility measurements (μ_eff = 5.9μ_B at 300 K) and EPR spectroscopy (g = 8.15, 3.44, and 1.66) establish a high-spin (HS) Fe(III) (S = 5/2) state despite the six-coordinate geometry. In contrast, the corresponding bis(1-MeIm) complex adopts a low-spin state (μ_eff = 2.0μ_B at 300 K), highlighting the critical role of axial ligation in controlling spin-state energetics. The isolation of 2 provides direct structural evidence for the mono(1-MeIm) intermediate proposed from solution titration studies. These findings reveal that expansion of the OxyPyP coordination cavity promotes stabilization of a six-coordinate HS Fe(III) state, providing a structural basis for tuning the electronic and magnetic properties of porphyrinoid iron complexes.

A ZnO : CeO₂/NiO ternary heterostructure with promising UV detection characteristics is introduced for the first time and was fabricated by a two-step process involving a hydrothermal method and spin-coating method. The XRD, SEM and EDX mapping results are in full agreement with the formation of a highly crystalline, phase-pure and homogeneously distributed ternary composite with a porous nanoflake morphology, which offers a high surface area for effective photon absorption and charge-carrier transport. The fabricated device demonstrates excellent optoelectronic properties under 5 V bias, with a high responsivity of about 165 mA W^-1, a specific detectivity of 4.8 × 10⁹ Jones and an external quantum efficiency (EQE) of 60% at 340 nm, which are much higher than those of pristine ZnO and binary ZnO : CeO₂. In addition, it is found that the photodetector has a high dynamic response speed (0.16 s for the response time and 0.25 s for the recovery time) and excellent operational stability and reproducibility for repeated switching cycles. The synergistic effect of CeO₂ and p-type NiO enhances photodetection performance. CeO₂ introduces intermediate energy states and helps control oxygen-vacancy-related defects, while NiO promotes efficient electron-hole separation and suppresses charge-carrier recombination. This also shows that the ZnO : CeO₂/NiO ternary heterostructure is a very attractive material for high-performance, environmentally friendly, energy-autonomous UV photodetectors for future portable and remote optoelectronic sensing systems.

Correction for 'Multimode coupled titanium-based multi-level nested cavity broadband solar absorber' by Yanxia Xu et al., Dalton Trans., 2026, https://doi.org/10.1039/d6dt01837h.

Nickel aluminate emerges concurrently with γ-alumina at the onset of the structural evolution of Ni²⁺-associated boehmite. Conventionally, spinel-type compounds on γ-alumina surfaces are generated through solid-state reactions between γ-alumina and metal salts at elevated temperatures. In this study, boehmite nanoparticles were generated through the hydrolysis and polycondensation of aluminum-tri-sec-butoxide in an aqueous solution containing Ni²⁺, producing dispersions in which Ni²⁺ ions were primarily associated with the particle surfaces rather than incorporated into the boehmite lattice. Upon calcination of the powder obtained by evaporation to dryness of the dispersion, the transformation of boehmite to γ-alumina at 400 °C was accompanied by the concurrent formation of NiAl₂O₄. Structural analyses using X-ray diffraction, solid-state ²⁷Al nuclear magnetic resonance, and electron microscopy indicate that the NiAl₂O₄ phase is segregated from the γ-alumina structure and is suggested to be preferentially localized near particle neck regions. This behavior contrasts with conventional impregnation approaches, in which spinel phases form at significantly higher temperatures through reactions between metal oxides and γ-alumina surfaces. In addition, the presence of NiAl₂O₄ delays the γ-to-θ transformation by approximately 100 °C. These results demonstrate that the structural evolution of Ni²⁺-associated boehmite provides a previously unrecognized pathway for generating spinel phases at the onset of γ-alumina formation. These findings therefore provide a new strategy for stabilizing the γ-phase and controlling the particle morphology of γ-alumina by introducing additives during precursor evolution rather than through post-impregnation processes.

Developing phosphite-based birefringent materials with simultaneously large birefringence and wide optical transparency remains a significant challenge. Inspired by the large intrinsic polarizability anisotropy of planar π-conjugated ligands, we introduced 1,10-phenanthroline (phen) into the magnesium phosphite system to explore the influence of ligand packing on birefringence. Colorless crystals of Mg(phen)(HPO₃) (1) and Mg(phen)(H₂PO₃)₂·H₂O (2) were successfully obtained under different solvothermal conditions. Although both compounds crystallize in the same monoclinic space group C2/c and consist of one-dimensional magnesium phosphite chains, they exhibit markedly different packing arrangements of the phen ligands. In compound 1, adjacent phen ligands are nearly perpendicular with a dihedral angle of approximately 90°, resulting in a birefringence of 0.36 at 546 nm. In contrast, compound 2 features a nearly parallel packing of the phen ligands and exhibits a remarkably large birefringence of 0.55 at 546 nm, placing it among the most birefringent phosphite-based materials reported to date. Theoretical calculations reveal that the birefringence is dominated by the π-conjugated phen ligands, while the phosphite groups make a much smaller contribution. These findings demonstrate that regulating the packing mode of π-conjugated ligands is an effective approach to enhancing birefringence in metal phosphite hybrids.