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This work demonstrates the development of mesoporous trimetallic oxide scaffolds (TOSs) as heterogeneous catalysts for the solvent-free transformation of CO2 into various value-added products. The TOS catalyst was prepared using a solution-combustion protocol as a time- and energy-saving method using cobalt, magnesium, and cerium metal nitrate salts as precursors and ethylene glycol as the fuel system and compared with their monometallic counterparts. Characterization suggested strong metal-metal and metal-oxygen interactions in the 3D-interconnected hierarchical porous network, which resulted in substantial alteration in the electronic, structural, and physicochemical properties. This resulted in an appreciable surface area, acid-base cooperative sites, and a larger pore volume in the catalyst. Thereafter, the CoMgCe-TOS catalyst was first used for the solvent-free cyclization of o-phenylenediamines and CO2 to produce benzimidazoles. In the presence of dimethylamine borane as a reductant, benzimidazoles were obtained in 94% yield at 100 °C under pressurized conditions, along with good recyclability for 12 cycles. It was established that selectivity toward benzimidazole improved upon the incorporation of basic metals (Mg and Ce), with Co aiding in the formation of cooperative Lewis acid-base sites. A plausible mechanism was also predicted, wherein the overall conversion of reactants for the N-formylation step was influenced by the number and strength of basic sites, and the cyclization step for selectively obtaining benzimidazole was affected by the acidic site strength. Besides the production of benzimidazole, the catalyst was also highly active for the synthesis of cyclic carbonates using epoxides and CO2 under optimized reaction conditions. This work therefore provides a new and greener route for the synthesis of benzimidazoles and organic carbonates, which can be easily adapted for scale-up applications.

Developing efficient carbon dioxide (CO2) capture and conversion methods is vital for climate change mitigation. Cycloaddition of CO2 with epoxides to form cyclic carbonates is a promising utilization method. In this study, a deep eutectic solvent‐modified dendritic fibrous nano‐silica (DES@DFNS) catalyst was synthesized by functionalizing DFNS with DES. This catalyst was used for the cycloaddition of CO2 with styrene oxide to produce styrene carbonate. The material's morphology and properties were characterized using various analytical techniques, revealing a high surface area, good porosity, and significant concentrations of Lewis acidic and basic sites. Rietveld refinement analysis provided insights into its phase composition, crystallite size, microstrain, stress, and other microstructural properties. Despite a lower surface area, DES@DFNS demonstrated superior catalytic activity. The interaction between DES and DFNS showed that DES was physically adsorbed onto the DFNS surface, contributing to its enhanced performance. Factors such as smaller crystallite size, higher microstrain, increased dislocation density, and improved elastic properties provided more active sites and greater mechanical stability, boosting overall efficiency and durability. The DES@DFNS catalyst achieved 99% conversion of styrene oxide with 96% selectivity and 95% yield of styrene carbonate at 120 °C for 10 h under solvent‐free, atmospheric conditions. The synergistic effect of Lewis acidic and basic sites on DES@DFNS supported catalytic activity under moderate conditions. Additionally, the catalyst demonstrated reusability, maintaining performance for up to six cycles without significant loss of activity, making it a promising candidate for sustainable CO2 fixation and valorization processes. [ABSTRACT FROM AUTHOR]

MXenes, a class of two-dimensional (2D) materials, have gathered significant attention as excellent electrode materials for various energy applications owing to their remarkable properties such as superior metallic conductivity, abundant surface functionality, high electrical conductivity, hydrophilicity, abundance of surface active sites, enormous cycle life, and ordered lamellar structure. In this study, we present the heterostructured growth of bimetallic Co-NiSe2 on MXene via a simple hydrothermal method. The resulting hybrid structure of Co-NiSe2 exhibits nanorod-like morphology wrapped around MXene sheets. When evaluated as an electrode material for supercapacitors, the Co-NiSe2/MXene composite demonstrates enhanced feasibility, displaying relatively high specific surface area and electrical conductivity, thus exhibiting excellent electrochemical performance. Specifically, the Co-NiSe2/MXene composite exhibits a high specific capacitance of 1394.8 F·g–1 at a current density of 1 A·g–1. Furthermore, the synergetic hybrid material can deliver a high energy density of 20 Wh·kg–1 at a power density of 684 W·kg–1. Importantly, the Co-NiSe2/MXene material exhibits good rate performance and cycle stability, showcasing its potential for advanced energy storage applications. [ABSTRACT FROM AUTHOR]

In this study, we presented hollow bimetallic mixed oxides of molybdenum and nickel, prepared through a facile polymer-assisted solution process. Our focus was on addressing the influence of polymer concentration on the formation of hollow nanoparticles (HNPs) of the bimetallic mixed oxides, a critical aspect explored through XRD, Raman, and TEM analyses. Raman study indicated that as the PAA concentration increases, the oxygen vacancies become more dominant with a decrease in the O/Mo ratio. The formation process of the hollow structure in the MoO3/NiMoO4 nanostructure was confirmed using FESEM and TEM. The influence of oxygen vacancies over the surface of the mixed oxides and their concentration was examined by XPS analysis. The resulting MoO3/NiMoO4 HNPs serve as catalysts for the oxygen evolution reaction (OER), and their performance was systematically investigated using ECSA, EIS, CV, and LSV analyses. The superior electrochemical performance of the optimized mixed oxide composite is attributed to the increased number of oxygen vacancies, electrical conductivity, and a reduced Tafel slope. Notably, the best composite exhibits a 3-fold increase in electrochemical surface area and a lower overpotential. Specifically, the reduction in the Tafel slope from 142.2 to 97.5 mV dec−1 and the overpotential from 402 to 330 mV for HNPs prepared with PAA 0.10 g/10 mL and PAA 0.15 g/10 mL, respectively, underscores the efficacy of the developed catalyst. DFT calculations of the OER were found to be uphill in energy which makes the *O to *OOH step the PDS for defective metal oxide with a ΔG of 3.00 eV. This research contributes valuable insights that open new avenues for the application of molybdenum oxides and their derivatives in water-splitting processes. The findings not only address the challenges in OER kinetics but also hold promise for advancing the field of green hydrogen production through enhanced electrocatalytic materials. [ABSTRACT FROM AUTHOR]

Numerous strategies exist to design a suitable bone graft made from polyurethane (PU) nanofibers. However, using PU nanofibers is impractical owing to their hydrophobicity. This work transforms the hydrophobicity of PU nanofibers using β‐cyclodextrin (β‐CD) and zinc oxide (ZnO) nanoparticles (NPs). Transmission and scanning electron microscopy (SEM) indicated the size of ~100 to 200 nm for ZnO NPs, and these NPs could finely harmonize inside nanofibers. The phenolphthalein absorbance test confirmed the inclusion of ZnO and β‐CD. Fourier transform infrared, X‐ray diffraction, and photoelectron spectroscopy showed that synthesized composites have intermolecular hydrogen interactions between the PU, β‐CD, and ZnO NPs. These embellishments improved the hydrophilicity from a contact angle of 60.2 ± 0.2° to 0°. The tensile strength of modified fibers increased from 2.16 ± 0.14 to 6.65 ± 6.0 MPa. The incorporation of ZnO NPs caused the mineralization of the nanofibers and the maximum number of hydroxyapatite NPs in the composite, which had the highest concentration of ZnO NPs. These nanofiber mats boosted the proliferation of Human Embryonic Kidney 293 T cells till 6 days of culture for the nanofiber with 5% β‐CD and 75 mg ZnO NPs combination. Cell fixation studies indicated the successful attachment of cells onto nanofibers. Consequently, our multifunctional scaffolds could be osteoproductive and osteoinductive biomaterials for future bone tissue engineering. [ABSTRACT FROM AUTHOR]

The anthropogenic carbon dioxide (CO2) fixation and various engineering strategies are gaining very significant attention because of the expansion of the net‐zero carbon environment in the atmosphere. Herein, we designed a sodium aluminate@γ‐alumina (NaAlO2@γ‐Al2O3) catalyst by a simple and facile precipitation and impregnation tactics. A series of different weight percentage NaAlO2@γ‐Al2O3 materials were successfully synthesized and well characterized by using advanced analytical and spectroscopic techniques such as TGA, XRD, FE‐SEM, TEM/HR‐TEM, FT‐IR, Raman, TPD, and XPS analysis. The NaAlO2@γ‐Al2O3 catalyst was employed as a competent catalyst for the CO2 fixation under atmospheric pressure reaction conditions. The catalytic activity results evidently revealed that the cycloaddition reaction successfully achieved 94% styrene oxide conversion and 93% selectivity, along with an 87% yield of the styrene carbonate at 120 °C for 6 h. Furthermore, we comprehensively examined the effect of different reaction parameters such as the effect of sodium aluminate amount, co‐catalyst amount, temperature, and time for CO2 fixation reaction. Additionally, different terminal and internal epoxides were tested under optimized reaction conditions and achieved moderate to excellent yield of the desired cyclic carbonate products. Interestingly, a plausible reaction mechanism was proposed for the styrene carbonate synthesis using NaAlO2@γ‐Al2O3 catalyst surface with the support of characterization and experimental results. Remarkably, the NaAlO2@γ‐Al2O3 catalyst could be easily recoverable and successfully recyclable up to six consecutive cycles without declining its initial catalytic activity along with stable structural and physicochemical properties. [ABSTRACT FROM AUTHOR]