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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.

Research studies on biomass-derived hard carbon are gaining notable scientific interest due to its potential application as a sustainable anode for Li-ion batteries (LIBs). The current study presents the development of hard carbon from soap-nut seed biomass, with the optimization of its pyrolysis temperature, followed by chemical activation using KOH- and ZnCl2-activated reagents. The physicochemical behaviour of the developed materials is studied by utilizing XRD, HRTEM, BET, and XPS techniques. CV and galvanostatic charge–discharge curves are examined to assess the potential of the material for the application as a sustainable anode in LIBs. The electrochemical performance of the developed materials obtained at various pyrolysis temperatures (600, 700, 800 and 900 °C) and chemically activated with KOH and ZnCl2 is explained with respect to their interplanar spacing, ID/IG ratio, and specific pore area. Among the different pyrolysis temperatures, the hard carbon pyrolyzed at 700 °C exhibits the maximum reversible specific discharge capacity of 391 mA h g−1 at a current density of 100 mA g−1. The present study also demonstrates that the electrochemical performance of the hard carbon deteriorates after chemical activation with ZnCl2, whereas chemical activation with KOH enhances its performance. The chemically-activated hard carbon using KOH exhibits a reversible specific discharge capacity of 454 mA h g−1 at 100 mA g−1 and delivers a better cycling stability (500 cycles) of 83 mA h g−1 at 300 mA g−1. [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]

Magnesium (Mg) has received very little exploration on its importance in the realm of battery‐type energy storage technologies. They are abundantly present in seawater, and if successfully extracted and utilized in energy storage systems, it could lead to the long‐term advancement of human civilization. Here, we fabricated an all‐solid‐state supercapacitor (ASSSC) using tellurium nanotubes decorated cobalt magnesium telluride microtubes (Te NTs@CoMgTe MTs) clad on nickel foam (NF). Owing to the unique mixed phase hierarchical structure, Te NTs@CoMgTe MTs showcases some advancement in energy storage performance. When tested in a three‐electrode system, multiphasic hybrid of elemental Te and metal tellurides, Te NTs@CoMgTe MTs outperforms the monometallic telluride owing to the strong synergistic interaction effect triggered from conductive three components and delivers a long‐life span performance up to 15,000 cycles. The fabricated Te NT@CoMgTe MT//AC solid‐state device exhibits a maximum areal capacity of 59.2 μAh cm−2 (56.3 mAh g−1) at a current density of 6 mA cm−2 with a maximum energy density of 42.2 Wh kg−1 (46.5 μWh cm−2) at a power density of 6857.1 W kg−1 (7574.6 μW cm−2). The performance of the device is rigid even at different bending angles (0 to 180°) which validates the extensibility of the process for future applications. [ABSTRACT FROM AUTHOR]