Inorganics

20 pages, 3801 KB

Open AccessArticle

Synthesis of MgO Doped with CoO/MgAl₂O₄, NiO/MgAl₂O₄, and CuO/MgAl₂O₄ in a Single Pot for Efficient Dye Adsorption

by Salah H. Elhory, Tarig G. Ibrahim, Mohamed R. Elamin, Faisal K. Algethami, Mohamed S. Eltoum, Babiker Y. Abdulkhair and Mutaz Salih

Inorganics 2026, 14(2), 44; https://doi.org/10.3390/inorganics14020044 - 30 Jan 2026

Abstract

A simple method employing dextrose as a capping agent was adopted for making MgAl₂O₄@MgO (AM), 5%NiO-MgAl₂O₄@MgO (AMNi), 5%CoO-MgAl₂O₄@MgO (AMCo), and 5%CuO-MgAl₂O₄@MgO (AMCu) nanocomposites. The average particle sizes, [...] Read more.

A simple method employing dextrose as a capping agent was adopted for making MgAl₂O₄@MgO (AM), 5%NiO-MgAl₂O₄@MgO (AMNi), 5%CoO-MgAl₂O₄@MgO (AMCo), and 5%CuO-MgAl₂O₄@MgO (AMCu) nanocomposites. The average particle sizes, determined via SEM, were in the range of 21.6–51.4 nm, 9.8–13.8 nm, 19.1–32.2 nm, and 9.2–31.2 nm for AM, AMCu, AMNi, and AMCo, respectively. The nanosorbents exhibited type IV isotherm curves and type H3 hysteresis loops, signifying mesoporous properties. The AM, AMCu, AMNi, and AMCo exhibited surface areas of 69.47, 95.87, 86.23, and 75.87 m²/g, respectively. The pseudo second order described the indigo carmine (IDC) sorptions onto AM, AMCu, AMNi, and AMCo. The liquid film diffusion regulated IDC sorption on AMNi and AMCo, whereas the intraparticle diffusion was the dominant model on AM and AMCu. The AMCu’s showed a q_t value of 127 mg g⁻¹ from a 50 mg L⁻¹ IDC solution at 20 °C, and 286.2 mg g⁻¹ from a 200 mg L⁻¹ IDC solution at 50 °C, establishing its capability for treating contaminated water. The IDC sorption onto AMCu aligns with the Freundlich model, which may elucidate the elevated q_t value of AMCu. Elevating the temperature induced the IDC sorption on AMCu, indicating its endothermic nature, and the negative ΔG° implied that the IDC sorption by AMCu was spontaneous. A 5.0 and 10.0 mg L⁻¹ IDC concentration in natural water samples was treated by the AMCu, which showed 100.0% efficacy for both groundwater samples; however, its efficacy toward the 5 and 10 mg L⁻¹ IDC in seawater was 99.23% and 89.78%, respectively. The MACu’s efficiency throughout four reuse cycles decreased by only 7.21%, demonstrating excellent stability and reusability performance. Full article

34 pages, 1929 KB

Open AccessReview

Photocatalytic Antibacterial Mechanism and Biotoxicity Trade-Off of Metal-Doped M-ZIF-8 (M=Co, Cu): Progress and Challenges

by Huili Ren, Chenxia Gao, Siqi Huang, Libo Du, Shuang Liu, Xi Cao and Yuguang Lv

Inorganics 2026, 14(2), 43; https://doi.org/10.3390/inorganics14020043 - 30 Jan 2026

Abstract

The proliferation of antibiotic resistance urgently demands the development of novel non-antibiotic-dependent antimicrobial strategies. Metal–organic framework material ZIF-8, with its tunable structure and excellent biocompatibility, shows great promise in the field of photocatalytic antibacterial applications. However, pure ZIF-8 suffers from limitations such as [...] Read more.

The proliferation of antibiotic resistance urgently demands the development of novel non-antibiotic-dependent antimicrobial strategies. Metal–organic framework material ZIF-8, with its tunable structure and excellent biocompatibility, shows great promise in the field of photocatalytic antibacterial applications. However, pure ZIF-8 suffers from limitations such as a narrow light absorption range and high carrier recombination rates. Doping ZIF-8 with transition metals such as cobalt or copper, herein denoted as M-ZIF-8 (M=Co, Cu), can significantly broaden its photoresponsive spectrum, promote reactive oxygen species (ROS) generation, and enable controlled metal ion release, thereby enhancing antimicrobial performance. Nevertheless, the release of metal ions also introduces potential biotoxicity concerns, limiting practical applications. This paper systematically reviews the trade-off between the photocatalytic antibacterial mechanism and biotoxicity of metal-doped M-ZIF-8 (M=Co, Cu), focusing on material design principles, antibacterial pathways, toxicity manifestations and mechanisms, as well as optimization strategies for “enhancing efficacy while reducing toxicity.” It further proposes future research challenges and directions in mechanism elucidation, smart material development, standardization, and industrialization to advance the safe and efficient application of these materials in medical and environmental fields. Full article

(This article belongs to the Special Issue Coordination and Organometallic Chemistry for Catalytic and Biomedical Applications)

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17 pages, 1468 KB

Open AccessArticle

Synthesis and Characterization of Palladium(II) Complexes of Cross-Bridged Tetraazamacrocycles

by Michael-Joseph Gorbet, Timothy J. Prior, Allen G. Oliver, Jeanette A. Krause and Timothy J. Hubin

Inorganics 2026, 14(2), 42; https://doi.org/10.3390/inorganics14020042 - 29 Jan 2026

Abstract

Ethylene cross-bridged tetraazamacrocycles have been used to stabilize first-row transition metal complexes for applications under harsh conditions, such as biomedical imaging and aqueous oxidation catalysis. We have applied these ligands to the synthesis of complexes of a larger second row transition metal, namely, [...] Read more.

Ethylene cross-bridged tetraazamacrocycles have been used to stabilize first-row transition metal complexes for applications under harsh conditions, such as biomedical imaging and aqueous oxidation catalysis. We have applied these ligands to the synthesis of complexes of a larger second row transition metal, namely, square pyramidal Pd²⁺ complexes, which may be useful for future catalytic processes. We now report the synthesis and crystal structure determination of four novel Pd²⁺ complexes of the general formula [PdLCl]PF₆, where L is the dimethyl ethylene cross-bridged derivative of 12aneN4 (cyclen), 13aneN4 (homocyclen), or 14aneN4 (cyclam), or the dibenzyl ethylene cross-bridged derivative of 14aneN4 (cyclam). Solid-state structures of all four complexes can be described as a distorted square pyramidal with τ₅ values ranging from 0.01 to 0.20, with three macrocycle nitrogen atoms and one chloride in the square base and the fourth ligand nitrogen constrained by the cross-bridge to the axial position. Cyclic voltammetry of the complexes in acetonitrile shows stabilization of the Pd³⁺ oxidation state by all four complexes. Electronic spectroscopy reveals the typical behavior for square pyramidal Pd²⁺. Full article

(This article belongs to the Section Coordination Chemistry)

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18 pages, 3122 KB

Open AccessArticle

Impact of Iron-Bearing Fillers on the Mechanical Strength and Chemical Stability of Magnesium Potassium Phosphate Matrices Incorporating Rhenium

by Sergey Sayenko, Volodymyr Shkuropatenko, Hans-Conrad zur Loye, Petr Vecernik, Monika Kiselova, Vlastislav Kašpar, Vlastimil Miller, Petr Bezdicka, Jan Šubrt, Petra Ecorchard, Natalija Murafa, Iva Milisavljevic and Scott T. Misture

Inorganics 2026, 14(2), 41; https://doi.org/10.3390/inorganics14020041 - 28 Jan 2026

Abstract

We report on the study of the immobilization process of non-radioactive rhenium (Re), a chemical analogue of technetium-99 (⁹⁹Tc), in compounds based on magnesium potassium phosphate (MKP), as well as the possibility of enhancing their properties with iron-bearing additives/fillers. Powdered Re [...] Read more.

We report on the study of the immobilization process of non-radioactive rhenium (Re), a chemical analogue of technetium-99 (⁹⁹Tc), in compounds based on magnesium potassium phosphate (MKP), as well as the possibility of enhancing their properties with iron-bearing additives/fillers. Powdered Re₂O₇ was used as the initial Re-containing source. Because of the solubility and high leachability of Tc (VII), which is also volatile at high temperatures, its immobilization for long-term storage and disposal poses a serious challenge to researchers. Taking this into account, low-temperature stabilization technology based on MKP, a cementitious material, is currently considered promising. We prepared experimental specimens based on Re-incorporated MKP matrices and analyzed their microstructure in detail using analytical methods of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Considering that iron-bearing substances can reduce Tc (VII) to the lower-valence form Tc (IV), which is more stable, attention was also paid to evaluate the effect of fillers (Fe₂O₃, Fe₃O₄, Fe, FeS and blast furnace slag (BFS)) on strength, oxidation state, and water resistance (expressed as leaching cumulative concentration). The addition of fillers ensures the formation of denser compounds based on MKP after 28 days of curing under ambient conditions and increases their mechanical strength. The oxidation state of Re and the reduction from Re (VII) to Re (IV) was estimated using X-ray-absorption near-edge structure (XANES) analysis. Considering the Re leaching concentrations from tests using the ANS-16.1 standard in water, enhanced leachability indices (LI) for Re from MKP matrices were determined with the addition of iron-bearing fillers. Overall, the average LI values were greater than the minimum limit, indicating their acceptance for disposal recommended by the U.S. Nuclear Regulatory Commission. Full article

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15 pages, 4701 KB

Open AccessArticle

Low-Temperature Co-Sintering of Li-Glass Solid Electrolytes and Li-Glass/Graphite Composite Anodes via Hot Press Processing

by Youngsun Ko, Hanbyul Lee, Wookyung Lee, Jaeseung Choi, Jungkeun Ahn, Youngsoo Seo and Chang-Bun Yoon

Inorganics 2026, 14(2), 40; https://doi.org/10.3390/inorganics14020040 - 27 Jan 2026

Abstract

With the expanding electric vehicle market, there is increasing demand for improved battery safety and fast-charging performance. Ceramic-based solid electrolytes have attracted attention due to their high thermal and electrochemical stabilities. Li-glass solid electrolytes (e.g., Li₂O–LiCl–B₂O₃–Al₂ [...] Read more.

With the expanding electric vehicle market, there is increasing demand for improved battery safety and fast-charging performance. Ceramic-based solid electrolytes have attracted attention due to their high thermal and electrochemical stabilities. Li-glass solid electrolytes (e.g., Li₂O–LiCl–B₂O₃–Al₂O₃, LCBA) are promising materials because they enable low-temperature sintering (<550 °C), suppress lithium volatilization, mitigate ionic conductivity degradation, and enable cost-effective manufacturing. LCBA can be co-sintered with graphite anodes to form composite anode materials for LCBA-based all-solid-state batteries. However, insufficient densification and shrinkage mismatch often lead to limited ionic conductivity and interfacial delamination. In this study, the sintering behavior of LCBA was investigated using a hot-press-assisted process, and LCBA/graphite composite anodes were co-sintered to evaluate their electrochemical and interfacial properties. The LCBA electrolyte sintered at 550 °C exhibited high densification and an ionic conductivity of 3.86 × 10⁻⁵ S cm⁻¹. Additionally, the composite containing 50 wt% LCBA achieved a maximum tensile stress of ~0.23 MPa and a high interfacial fracture energy of ~180–200 J m⁻², indicating enhanced deformation tolerance and fracture resistance. This approach improves the densification, ionic conductivity, and interfacial mechanical stability of LCBA solid electrolytes and their composite anodes, highlighting their potential for next-generation all-solid-state secondary battery applications. Full article

(This article belongs to the Special Issue Structure and Component-Designed Functional Materials for Electrochemical Application)

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14 pages, 3338 KB

Open AccessArticle

Synthesis of Copper, Silver, and Copper–Silver Powders by Hydrogen-Assisted Ultrasonic Spray Pyrolysis

by Mame Haicha Faye, Duško Kostić, Srećko Stopić, Kone Daouda, Aleksandar M. Mitrašinović, Tatjana Volkov Husović, Jiehua Li and Bernd Friedrich

Inorganics 2026, 14(2), 39; https://doi.org/10.3390/inorganics14020039 - 27 Jan 2026

Abstract

Copper (Cu), silver (Ag), and copper–silver (Cu–Ag) powders were synthesized using ultrasonic spray pyrolysis (USP) combined with hydrogen-assisted reduction in order to examine how key processing parameters influence particle characteristics. The effects of reduction temperature, gas atmosphere, and precursor molar ratio on particle [...] Read more.

Copper (Cu), silver (Ag), and copper–silver (Cu–Ag) powders were synthesized using ultrasonic spray pyrolysis (USP) combined with hydrogen-assisted reduction in order to examine how key processing parameters influence particle characteristics. The effects of reduction temperature, gas atmosphere, and precursor molar ratio on particle morphology, size distribution, and elemental composition were systematically investigated. Aqueous precursor solutions of copper nitrate trihydrate and silver nitrate were atomized in a USP reactor and thermally treated under hydrogen-containing or argon atmospheres at temperatures between 500 and 700 °C. The resulting powders were characterized by scanning electron microscopy (SEM), particle size analysis using ImageJ, and energy-dispersive X-ray spectroscopy (EDS). The results showed that both temperature and gas atmosphere strongly affected particle formation. Hydrogen-assisted synthesis promoted efficient reduction and high metal purity but was associated with increased particle coalescence, whereas argon atmospheres yielded finer and more uniform particles through thermally driven decomposition. In the case of Cu–Ag powders, the precursor molar ratio played a decisive role in particle stability. A 1:1 Cu:Ag ratio produced uniform particles with reduced susceptibility to surface oxidation, while Ag-rich compositions (1:3 Cu:Ag) showed increased agglomeration and partial oxidation after synthesis. Overall, this study demonstrates that careful adjustment of gas atmosphere, synthesis temperature, and precursor composition enables control over the morphology and compositional stability of Cu, Ag, and Cu–Ag powders produced by USP. These findings provide practical guidance for the scalable preparation of mono- and bimetallic metal powders for applications in electronics, catalysis, and energy-related technologies. Full article

(This article belongs to the Section Inorganic Materials)

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12 pages, 677 KB

Open AccessArticle

Rhodium Tris(hydroxymethyl)phosphine (THP)/Amine Complexes as Stable Effective Homogenous Hydrogenation Catalysts in Aqueous Solution

by Sai Ge, Yuxin Lin and Manluan Sun

Inorganics 2026, 14(2), 38; https://doi.org/10.3390/inorganics14020038 - 26 Jan 2026

Abstract

Green chemistry, achieved by using water as a reaction medium, has several potential applications. In this work, a number of water-soluble Rh(III)–THP complexes, [Rh(III)Cl₃(OH)(THP)₂]⁻ (1), [Rh(III)Cl₂(OH)(THP)₃] (2), [Rh(III)Cl(OH)(THP)₄] [...] Read more.

Green chemistry, achieved by using water as a reaction medium, has several potential applications. In this work, a number of water-soluble Rh(III)–THP complexes, [Rh(III)Cl₃(OH)(THP)₂]⁻ (1), [Rh(III)Cl₂(OH)(THP)₃] (2), [Rh(III)Cl(OH)(THP)₄]⁺ (3), [Rh(III)Cl(OH)(en)(THP)₂]⁺ (4a), [Rh(I)(en)(THP)₂]⁺ (4b) and [Rh(III)(en)₂Cl₂]Cl (5) (where THP = P(CH₂OH)₃), were generated in aqueous media by controlling the reaction at different molar ratios of RhCl₃/THP/en (en: ethylenediamine). These complexes were fully characterized in situ by ³¹P NMR spectroscopy, base titration and by X-ray crystallography for the solid compound (4). The catalytic hydrogenation reactivities of freshly prepared complexes (1–5) were tested in situ with the selected substrate of 3,4-dimethoxystyrene under the same experimental conditions; the related catalytic reactivities are discussed in detail. Full article

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17 pages, 4675 KB

Open AccessArticle

The Synthesis of Tetrakis(N,N-dimethylaminomethyl)ferrocene and Its Bimetallic Nickel(II) Dichloride Complex: The Search for Precursors for Methoxycarbonylation Ligands

by Ian R. Butler, Peter N. Horton, William Clegg, Simon J. Coles, Loretta Murphy and Steven Elliott

Inorganics 2026, 14(2), 37; https://doi.org/10.3390/inorganics14020037 - 26 Jan 2026

Abstract

The family of N,N-dimethylaminomethylferrocene compounds is one of the most important in ferrocene chemistry. They serve as precursors for a range of anti-malarial and anti-tumour medicinal compounds, in addition to being key precursors for ferrocene ligands in the Lucite alpha [...] Read more.

The family of N,N-dimethylaminomethylferrocene compounds is one of the most important in ferrocene chemistry. They serve as precursors for a range of anti-malarial and anti-tumour medicinal compounds, in addition to being key precursors for ferrocene ligands in the Lucite alpha process. A brief discussion on the importance and synthesis of N,N-dimethylaminomethyl-substituted ferrocenes preludes the synthesis of the new ligand, 1,1′,2,2′-tetrakis-(N,N-dimethylaminomethyl)ferrocene. The crystal structure of this compound is reported, and a comparison is made with its disubstituted analogue, 1,2-bis-(N,N-dimethylaminomethyl)ferrocene. The tetrahedral nickel dichloride complexes of both these ligands have been crystallographically characterised. Finally, a pointer to future research in the area is given, which includes a discussion of a new method to extract ferrocenylmethylamines from mixtures using additives and a new synthetic avenue from substituted cyclopentadiene itself. Full article

(This article belongs to the Section Organometallic Chemistry)

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22 pages, 4846 KB

Open AccessArticle

Carbon-NiTiO₂ Nanosorbent as Suitable Adsorbents for the Detoxification of Zn²⁺ Ions via Combined Metal–Oxide Interfaces

by Azizah A. Algreiby, Abrar S. Alnafisah, Muneera Alrasheedi, Tahani M. Alresheedi, Ajayb Alresheedi, Abuzar Albadri and Abueliz Modwi

Inorganics 2026, 14(2), 36; https://doi.org/10.3390/inorganics14020036 - 26 Jan 2026

Abstract

Metal ions exemplify one of the most harmful and environmentally detrimental contaminants of water systems. This work describes the creation of an innovative chelated carbon-doped nickel and titanium oxide (C-NiTiO₂) hybrid as an adsorbent for the effective elimination of metal ions. [...] Read more.

Metal ions exemplify one of the most harmful and environmentally detrimental contaminants of water systems. This work describes the creation of an innovative chelated carbon-doped nickel and titanium oxide (C-NiTiO₂) hybrid as an adsorbent for the effective elimination of metal ions. The dominance of the TiO₂ anatase phase with a ≈ 61 nm crystallite size was verified by XRD and Raman investigation. Morphology investigations exposed polygonal nanoparticles consisting of Ti, C, Ni, and O. The nanostructure exhibited a surface area of 17 m²·g⁻¹, a pore diameter of ≈1.5 nm, and a pore volume of 0.0315 cm³·g⁻¹. The nanostructure was evaluated for the elimination of Zn (II) ions from an aqueous solution. The metal ion adsorption onto the hybrid nanomaterial was described and comprehended using adsorption kinetics and equilibrium models. The adsorption data matched well with the pseudo-second-order kinetics and Langmuir adsorption models, indicating a monolayer chemisorption mechanism and achieving a maximum Zn (II) ion elimination of 369 mg·g⁻¹. Mechanistic investigation indicated film diffusion-controlled adsorption through inner-sphere complexation. The nanosorbent could be regenerated and reused for four rounds without appreciable activity loss, thus demonstrating its potential for water cleanup applications. Full article

(This article belongs to the Section Inorganic Materials)

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17 pages, 2736 KB

Open AccessArticle

Pt Single-Atom Doping in Ag₂₉ Nanoclusters for Enhanced Band Bending and Z-Scheme Charge Separation in TiO₂ Heterojunction Photocatalysts

by Xiao-He Liu, Rui Yuan, Zhi Li, Jing Wang, Nailong Zhao and Zhili Ren

Inorganics 2026, 14(2), 35; https://doi.org/10.3390/inorganics14020035 - 26 Jan 2026

Abstract

In recent years, metal nanoclusters (NCs) with atomic-scale precision have emerged as novel photosensitizers for light energy conversion in metal cluster-sensitized semiconductor (MCSS) systems. However, conventional NCs often suffer from photodegradation after binding with semiconductors, limiting their long-term catalytic stability. Modifying NCs via [...] Read more.

In recent years, metal nanoclusters (NCs) with atomic-scale precision have emerged as novel photosensitizers for light energy conversion in metal cluster-sensitized semiconductor (MCSS) systems. However, conventional NCs often suffer from photodegradation after binding with semiconductors, limiting their long-term catalytic stability. Modifying NCs via single-atom doping provides an effective strategy to tailor their interfacial charge transfer behavior. In this study, PtAg₂₈ NCs were synthesized by doping Pt single atoms into Ag₂₉ NCs and subsequently loaded onto TiO₂ via electrostatic adsorption to construct composite photocatalysts. Systematic investigations revealed that Pt doping significantly enhances light absorption and promotes the formation of a direct Z-scheme heterojunction. The optimized PtAg₂₈/TiO₂ composite exhibits effective suppression of charge recombination. This enhanced charge separation efficiency, driven by pronounced band bending at the interface, leads to a remarkable hydrogen evolution rate of 14,564 μmol g⁻¹ h⁻¹. This work demonstrates the critical role of single-atom doping in regulating the photophysical properties of metal NCs and offers a feasible approach for designing highly efficient and stable metal-cluster-based photocatalytic systems. Full article

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15 pages, 1863 KB

Open AccessArticle

Designing a Cr³⁺-Based Transition Metal Catalyst: Redox-Mediated Low-Temperature Activation for Strong Solid Base Generation

by Tiantian Li, Xiaowen Li, Hao Wu, Qunyu Chen, Hao Zhou, Xiaochen Lin and Dingming Xue

Inorganics 2026, 14(2), 34; https://doi.org/10.3390/inorganics14020034 - 25 Jan 2026

Abstract

Solid base catalysts hold significant promise for replacing traditional homogeneous bases with green chemical processes. However, the construction of their strong basic sites typically relies on high-temperature calcination, which often leads to the collapse of the carrier structure and high energy consumption. This [...] Read more.

Solid base catalysts hold significant promise for replacing traditional homogeneous bases with green chemical processes. However, the construction of their strong basic sites typically relies on high-temperature calcination, which often leads to the collapse of the carrier structure and high energy consumption. This study proposes a novel “carrier reducibility tuning” strategy, which involves endowing the carrier with intrinsic reducibility to induce the low-temperature decomposition of alkali precursors via a redox pathway, thereby enabling the mild construction of strong basic sites. Low-valence Cr³⁺ was doped into a mesoporous zirconia framework, successfully fabricating an MCZ carrier with a mesostructure and reducible characteristics. Characterization results indicate that a significant redox interaction between the Cr³⁺ in the carrier and the supported KNO₃ occurs at 500 °C. This interaction facilitates the complete conversion of KNO₃ into highly dispersed, strongly basic K₂O species, while Cr³⁺ is predominantly oxidized to Cr⁶⁺. This activation temperature is approximately 300 °C lower than that required for the conventional thermal decomposition pathway and effectively preserves the structural integrity of the material. In the transesterification reaction for synthesizing dimethyl carbonate, the prepared catalyst exhibits superior catalytic activity, significantly outperforming classic solid bases like MgO and other reference catalysts. Full article

(This article belongs to the Special Issue Transition Metal Catalysts: Design, Synthesis and Applications)

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11 pages, 3059 KB

Open AccessArticle

Integrated Effects of NiCo₂O₄ and Reduced Graphene Oxide in High-Performance Supercapacitor Systems

by Radhika Govindaraju, Ananthi Balakrishnan, Neela Mohan Chidambaram, Vediyappan Thirumal, Palanisamy Rajkumar and Jinho Kim

Inorganics 2026, 14(2), 33; https://doi.org/10.3390/inorganics14020033 - 24 Jan 2026

Abstract

Supercapacitors have attracted significant interest as increased energy storage devices due to their high power density, rapid charge/discharge performance, and long cyclability. In this study, NiO, Co₃O₄, NCO, and NCO/rGO composite electrodes were prepared and evaluated for high-performance supercapacitor [...] Read more.

Supercapacitors have attracted significant interest as increased energy storage devices due to their high power density, rapid charge/discharge performance, and long cyclability. In this study, NiO, Co₃O₄, NCO, and NCO/rGO composite electrodes were prepared and evaluated for high-performance supercapacitor applications. The uniform distribution of elements and the effective incorporation of rGO into the composite were confirmed by structural and morphological characterizations. Among the evaluated materials, the NCO/rGO electrode exhibited high electrochemical performance, delivering a specific capacitance of 998 F g⁻¹ in a three-electrode configuration, attributed to the enhanced redox activity of NiCo₂O₄ coupled with the enhanced electrical conductivity of rGO. Additionally, an asymmetric supercapacitor device with activated carbon as the negative electrode and NCO/rGO as the positive electrode showed a power density of 750 W kg⁻¹, an energy density of 29.2 Wh kg⁻¹, and a specific capacitance of 93.7 F g⁻¹. After 5000 charge/discharge cycles, the device maintained 85% of its initial capacitance and a coulombic efficiency of 99%, demonstrating exceptional cyclability. These results highlight the strong potential of the NiCo₂O₄/rGO composite as an advanced electrode material for next-generation energy storage systems. Full article

(This article belongs to the Special Issue Structure and Component-Designed Functional Materials for Electrochemical Application)

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31 pages, 7306 KB

Open AccessReview

From Porphyrinic MOFs and COFs to Hybrid Architectures: Design Principles for Photocatalytic H₂ Evolution

by Maria-Chrysanthi Kafentzi, Grigorios Papageorgiou and Kalliopi Ladomenou

Inorganics 2026, 14(2), 32; https://doi.org/10.3390/inorganics14020032 - 23 Jan 2026

Abstract

Solar-driven hydrogen production via photocatalytic water splitting represents a promising route toward sustainable and low-carbon energy systems. Among emerging photocatalysts, porphyrin-based framework materials, specifically porphyrinic metal–organic frameworks (PMOFs) and porphyrinic covalent organic frameworks (PCOFs), have attracted increasing attention owing to their strong visible-light [...] Read more.

Solar-driven hydrogen production via photocatalytic water splitting represents a promising route toward sustainable and low-carbon energy systems. Among emerging photocatalysts, porphyrin-based framework materials, specifically porphyrinic metal–organic frameworks (PMOFs) and porphyrinic covalent organic frameworks (PCOFs), have attracted increasing attention owing to their strong visible-light absorption, tunable electronic structures, permanent porosity, and well-defined catalytic architectures. In these systems, porphyrins function as versatile photosensitizers whose photophysical properties can be precisely tailored through metalation, peripheral functionalization, and integration into ordered frameworks. This review provides a comprehensive, design-oriented overview of recent advances in PMOFs, PCOFs, and hybrid porphyrinic architectures for photocatalytic H₂ evolution. We discuss key structure–activity relationships governing light harvesting, charge separation, and hydrogen evolution kinetics, with particular emphasis on the roles of porphyrin metal centers, secondary building units, linker functionalization, framework morphology, and cocatalyst integration. Furthermore, we highlight how heterojunction engineering through coupling porphyrinic frameworks with inorganic semiconductors, metal sulfides, or single-atom catalytic sites can overcome intrinsic limitations related to charge recombination and limited spectral response. Current challenges, including long-term stability, reliance on noble metals, and scalability, are critically assessed. Finally, future perspectives are outlined, emphasizing rational molecular design, earth-abundant catalytic motifs, advanced hybrid architectures, and data-driven approaches as key directions for translating porphyrinic frameworks into practical photocatalytic hydrogen-generation technologies. Full article

(This article belongs to the Section Inorganic Materials)

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11 pages, 1102 KB

Open AccessArticle

Pulsed EPR Study of the Interaction Between ²³Na⁺ and Flavin in the Sodium-Pumping NADH:Ubiquinone Oxidoreductase (NQR) from Vibrio cholerae

by Sergei A. Dikanov and Robert B. Gennis

Inorganics 2026, 14(1), 31; https://doi.org/10.3390/inorganics14010031 - 20 Jan 2026

Abstract

Sodium-pumping NADH: ubiquinone oxidoreductase (Na⁺-NQR) is an important component of the aerobic respiratory chain of Vibrio cholerae. It oxidizes NADH, reduces ubiquinone, and uses the free energy of this redox reaction to move sodium across the cell membrane. The enzyme [...] Read more.

Sodium-pumping NADH: ubiquinone oxidoreductase (Na⁺-NQR) is an important component of the aerobic respiratory chain of Vibrio cholerae. It oxidizes NADH, reduces ubiquinone, and uses the free energy of this redox reaction to move sodium across the cell membrane. The enzyme is a membrane complex of six subunits, two 2Fe−2S centers, and four flavins. Both the oxidized and reduced forms of Na⁺-NQR exhibit EPR signals due to flavin semiquinone radicals. It has been shown that in the oxidized form of the enzyme, the radical is a neutral flavin, while in the NADH-reduced form, the radical is an anionic flavin. Electron Spin Echo Envelope Modulation Spectroscopy (ESEEM) was used to probe the presence of the magnetic nucleus ²³Na in the immediate vicinity of the paramagnetic centers. The contribution of the ²³Na nucleus was observed only in the ESEEM spectra of the anionic flavin semiquinone previously assigned to FMN_NqrB. Analysis shows that the Na⁺ ion is within ~3–4 Å of the flavin radical. This distance is consistent with two models: (i) complexation of the Na⁺ ion with the carbonyl group of CO4; or alternatively, (ii) a “cation-π interaction,” between Na⁺ and the electron-rich π-system of the flavin aromatic rings. Full article

(This article belongs to the Special Issue Feature Papers in Bioinorganic Chemistry 2026)

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13 pages, 4761 KB

Open AccessArticle

Low Molecular Weight Acid-Modified Aluminum Nitride Powders for Enhanced Hydrolysis Resistance

by Linguang Wu, Yaling Yu, Shaomin Lin, Xianxue Li, Chenyang Zhang and Ji Luo

Inorganics 2026, 14(1), 30; https://doi.org/10.3390/inorganics14010030 - 18 Jan 2026

Abstract

Aluminum nitride (AlN) possesses an exceptional combination of high thermal conductivity and an ultra-wide band gap, rendering it highly attractive for electronic packaging and semiconductor substrate applications. In this study, surface chemical modification of AlN powders was performed employing low-molecular-weight organic acids, successfully [...] Read more.

Aluminum nitride (AlN) possesses an exceptional combination of high thermal conductivity and an ultra-wide band gap, rendering it highly attractive for electronic packaging and semiconductor substrate applications. In this study, surface chemical modification of AlN powders was performed employing low-molecular-weight organic acids, successfully yielding hydrolysis-resistant AlN powders. The underlying mechanisms responsible for the improved anti-hydrolysis performance imparted by both single organic acids and the composite acid were systematically investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM), characterization techniques. The results reveal that Oxalic acid within the concentration range of 0.25 M to 1.50 M partially inhibits the hydrolysis of aluminum nitride (AlN); however, hydrolysis products such as aluminum hydroxide are still formed. In the case of citric acid, a higher concentration leads to a stronger anti-hydrolysis effect on the modified AlN. No significant hydrolysis products were detected when the AlN sample was treated in a 1 M aqueous citric acid solution at 80 °C. The effectiveness of the organic acids in enhancing the hydrolysis resistance of AlN follows the order: composite acid (citric acid + oxalic acid) > citric acid > oxalic acid. Under the action of the composite acid, the AlN diffraction peaks exhibit the highest intensity. Furthermore, TEM observations reveal the formation of an amorphous protective layer on the surface, which contributes to the improved hydrolysis resistance. Analytical results confirmed that the surface modification process, mediated by citric acid, oxalic acid, or the composite acid, involved an esterification-like reaction between the surface hydroxyl groups on AlN and the chemical modifiers. This reaction led to the formation of a continuous protective coordination layer encapsulating the AlN particles, which serves as an effective diffusion barrier against water molecules, thereby significantly inhibiting the hydrolysis reaction. Full article

(This article belongs to the Section Inorganic Materials)

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13 pages, 2628 KB

Open AccessArticle

Electrical Properties and Charge Transfer Mechanisms in Nanoscale Anodic TiO₂ Films at Low Applied Voltages

by Vyacheslav A. Moshnikov, Ekaterina N. Muratova, Igor A. Vrublevsky, Alexandr I. Maximov, Andrey A. Ryabko, Alena Yu. Gagarina and Dmitry A. Kozodaev

Inorganics 2026, 14(1), 29; https://doi.org/10.3390/inorganics14010029 - 17 Jan 2026

Abstract

The current–voltage characteristics (IVCs) of anodic TiO₂ films in a thin-film structure (Carbon paste/TiO₂/Ti/Al) were investigated in the temperature range of T = 80–300 K with bias voltages from −0.5 V to +0.5 V. Anodic oxide film, with a thickness [...] Read more.

The current–voltage characteristics (IVCs) of anodic TiO₂ films in a thin-film structure (Carbon paste/TiO₂/Ti/Al) were investigated in the temperature range of T = 80–300 K with bias voltages from −0.5 V to +0.5 V. Anodic oxide film, with a thickness of 14 nm, was obtained by electrochemical oxidation of Ti at a voltage of 10 V. The obtained data for various temperatures showed that the IVCs in the forward (negative on the Ti electrode) and reverse (positive on the Ti electrode) bias of the thin film structure are not symmetrical. Based on the analysis, three temperature ranges (sections) were identified in which the IVCs differ in their behavior. Examination of the IVCs revealed that the conductivity mechanism in Section I (temperature range from 298 to 263 K) is determined by the Space Charge Limited Current (SCLC). Section II, in the temperature range from 243 to 203 K, is characterized by the onset of conductivity involving donor centers, in the case where the concentration of electrons on traps is significantly higher than the concentration of electrons in the conduction band. In Section III, within the temperature range from 183 to 90 K, the conduction mechanism is the Poole–Frenkel process involving donor centers. These donor centers are located below the level of traps in the forbidden band. The results obtained indicate that anodic TiO₂ is an n-type semiconductor, in the bandgap of which there are both electron traps and donor centers formed by anionic (oxygen) vacancies. The different behavior of the characteristic energy with different sample biasing in the case of the Poole–Frenkel mechanism indicates a two-layer structure of anodic TiO₂. Full article

(This article belongs to the Special Issue Advanced Inorganic Nanomaterials for Energy Conversion and Catalysis Applications, 2nd Edition)

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16 pages, 3760 KB

Open AccessArticle

A DFT Study on Sc-Catalyzed Diastereoselective Cyclization of 2-Picoline with 1,5-Hexadiene: Mechanism and Origins of Regio- and Stereoselectivity

by Guangli Zhou, Shuangxin Zhai, Xia Leng, Yunzhi Li, Qiying Xia and Yi Luo

Inorganics 2026, 14(1), 28; https://doi.org/10.3390/inorganics14010028 - 16 Jan 2026

Abstract

Density functional theory (DFT) calculations elucidate the mechanism of diastereoselective cyclization of 2-picoline with 1,5-hexadiene catalyzed by a cationic half-sandwich scandium complex. The catalytic cycle proceeds through four key stages: formation of active species, initial alkene insertion, cis-selective cyclization, and protonation. Central [...] Read more.

Density functional theory (DFT) calculations elucidate the mechanism of diastereoselective cyclization of 2-picoline with 1,5-hexadiene catalyzed by a cationic half-sandwich scandium complex. The catalytic cycle proceeds through four key stages: formation of active species, initial alkene insertion, cis-selective cyclization, and protonation. Central to the mechanism is the dual role of 2-picoline, which initially coordinates as a supporting ligand to facilitate C–H activation and regioselective 1,2-insertion but must dissociate to enable stereocontrol. The mono(2-picoline)-coordinated complex C3 is identified as the thermodynamically favored active species. C–H activation reactivity follows the trend: ortho-C(sp²)–H (2-picoline-free) > ortho-C(sp²)–H (2-picoline-coordinated) > benzylic C(sp³)–H (2-picoline-free) > benzylic C(sp³)–H (2-picoline-coordinated), a preference governed by a wider C_α–Sc–C_α′ angle and shorter Sc···X (X = C_α, C_α′, H) distances that enhance scandium–substrate interaction. Subsequent 1,5-hexadiene insertion proceeds with high 1,2-regioselectivity through a picoline-assisted pathway. The stereoselectivity-determining step reveals a mechanistic dichotomy: while picoline coordination is essential for initial activation, its dissociation is required for intramolecular cyclization. This ligand displacement avoids prohibitive steric repulsion in the transition state, directing the reaction exclusively toward the cis-cyclized product. The cycle concludes with a sterically accessible mono-coordinated protonation. This work establishes a “ligand-enabled then ligand-displaced” mechanism, highlighting dynamic substrate coordination as a critical design principle for achieving high selectivity in rare-earth-catalyzed C–H functionalization. Full article

(This article belongs to the Section Coordination Chemistry)

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12 pages, 3283 KB

Open AccessArticle

Amidine-Linked Closo-Dodecaborate–Silica Hybrids: Synthesis and Characterization

by Alexey V. Nelyubin, Nikolay K. Neumolotov, Vsevolod A. Skribitsky, Maria A. Teplonogova, Nikita A. Selivanov, Alexander Yu. Bykov, Victor P. Tarasov, Andrey P. Zhdanov, Konstantin Yu. Zhizhin and Nikolay T. Kuznetsov

Inorganics 2026, 14(1), 27; https://doi.org/10.3390/inorganics14010027 - 14 Jan 2026

Abstract

Silica-based sorbents covalently modified with polyhedral boron clusters represent a promising platform for highly selective separation materials, yet robust and synthetically accessible immobilization protocols remain underdeveloped. In this work, novel sorbents based on commercially available silica gels functionalized with closo-dodecaborate anions were [...] Read more.

Silica-based sorbents covalently modified with polyhedral boron clusters represent a promising platform for highly selective separation materials, yet robust and synthetically accessible immobilization protocols remain underdeveloped. In this work, novel sorbents based on commercially available silica gels functionalized with closo-dodecaborate anions were synthesized and systematically characterized. Two immobilization strategies were compared: direct nucleophilic addition of surface aminopropyl groups to the nitrilium derivative (Bu₄N)[B₁₂H₁₁NCCH₃] and sol–gel condensation of a pre-formed boron-containing APTES-derived silane. Covalent attachment via amidine bond formation was confirmed by solution and MAS ¹¹B NMR spectroscopy, IR spectroscopy, elemental analysis/ICP-OES, and SEM. The direct grafting route afforded a boron loading of 4.5 wt% (≈20% of the theoretical capacity), with the efficiency limited by electrostatic repulsion between anionic amidine fragments on the negatively charged silica surface, whereas the APTES route gave lower absolute loading (0.085 mmol/g) due to the low specific surface area of the coarse silica support. Despite the moderate degree of functionalization, the resulting boron cluster–modified silica gels are attractive candidates for specialized chromatographic applications, where the unique hydrophobic and dihydrogen-bonding properties of closo-dodecaborates may enable selective retention of challenging analytes and motivate further optimization of surface morphology and immobilization conditions. Full article

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21 pages, 2284 KB

Open AccessArticle

Synthesis, Characterization and Anticancer Activities of Zn²⁺, Ni²⁺, Co²⁺, and Cu²⁺ Complexes of 4-Benzopyranone-2-carboxylic Acid

by Qianqian Kang, Qasim Umar, Wenjie Zhang, Xianggao Meng, Hao Yin, Mei Luo and Yanmin Zhang

Inorganics 2026, 14(1), 26; https://doi.org/10.3390/inorganics14010026 - 12 Jan 2026

Abstract

Coordination complexes play a crucial role in modern research. 4-benzopyranone-2-carboxylic acid is a fascinating class of molecules with numerous applications, including the synthesis of pharmaceuticals and valuable chiral compounds. Antibacterial and tuberculostatic medicines, HIV protease inhibitors, intermediates in organic synthesis, and organic catalysis [...] Read more.

Coordination complexes play a crucial role in modern research. 4-benzopyranone-2-carboxylic acid is a fascinating class of molecules with numerous applications, including the synthesis of pharmaceuticals and valuable chiral compounds. Antibacterial and tuberculostatic medicines, HIV protease inhibitors, intermediates in organic synthesis, and organic catalysis are only a few of the biological applications of chiral complexes. In this study, the synthesis of four metal complexes, C₃₀H₂₈N₂NiO₁₂ [Ni(bzpyr)₂(py)₂(H₂O)₂] (I), C₃₀H₂₄CoN₂O₁₀ [Co(bzpyr)₂(py)₂(H₂O)₂] (II), C₂₀H₂₀O₁₃Zn [Zn(bzpyr)₂(H₂O)₃] (III), and C₃₀H₂₂CuN₂O₉ [Cu(bzpyr)₂(py)₂(H₂O)] (IV), is reported via direct reactions of 4-benzopyranone-2-carboxylic acid with metal salts and pyridine in anhydrous ethanol. Single-crystal X-ray diffraction analysis revealed that complexes I and II crystallize in the chiral space group P-1, whereas III and IV crystallize in the centrosymmetric space group P2₁/c. The structures of these complexes were further characterized by infrared spectroscopy, UV-Visible Diffuse Reflectance Spectroscopy, electrospray ionization mass spectrometry (ESI-MS), elemental analysis, nuclear magnetic resonance, electron paramagnetic resonance spectroscopy and single-crystal X-ray diffraction. In addition, the cytotoxic activities of complexes I–IV were evaluated against the human tumor cell lines K562, A549, HepG2, MDA-MB-231, and SW480, and molecular docking studies were conducted on the four complexes. Full article

(This article belongs to the Special Issue Metal Complexes Containing Bioactive Ligands: Structure and Biological Evaluation, 2nd Edition)

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