Catalytic efficiency of GO-PANI nanocomposite in the synthesis of N-Aryl-1,4-Dihydropyridine and hydroquinoline derivatives

In this research, graphene oxide-polyaniline (GO-PANI) nanocomposite was successfully synthesized and its catalytic performance was evaluated for the synthesis of N-aryl-1,4-dihydropyridine (1,4-DHP) and hydroquinoline derivatives. The GO nanosheets were prepared using the Hummers' method, and in-situ polymerization of aniline was conducted with ammonium persulfate (APS) serving as the polymerization initiator. The synthesized nanocomposite demonstrated notable efficiency, achieving yields of 80-94% for 1,4-DHP derivatives and 84-96% for hydroquinoline derivatives. The GO-PANI nanocomposite was thoroughly characterized by various techniques, including Fourier Transforms Infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction analysis (XRD), Thermogravimetric analysis (TGA), and Energy Dispersive X-ray spectroscopy (EDS), all of which confirmed the successful synthesis of the nanocomposite. Furthermore, after ten cycles of reusability testing, the nanocomposite retained its high catalytic performance with no significant degradation. This findings indicate that the GO-PANI nanocomposite is a promising non-metal catalyst for the synthesis of N-aryl-1,4-dihydropyridine and hydroquinoline derivatives.

Boron-, sulfur-, and phosphorus-doped graphene for environmental applications

The control of environmental pollutants is a global concern. Recently, heteroatom-doped graphene has drawn increasing attention due to their widespread applications in removing and detecting environmental pollutants. Owing to the introduction of heteroatoms into pristine graphene, the properties of heteroatom-doped graphene have been significantly enhanced in physic, chemistry, and biology. This review focuses on the approaches for synthesis and characterization of boron-, sulfur-, and phosphorus-doped graphene and their applications in the fields of adsorption, catalysis, and detection for environmental pollutants. The mechanisms of environmental applications, including π-π interactions, complexation, hydrophobic interactions, electronic conductivity, and active sites and reactive radicals, are elaborated. Furthermore, the challenges associated with the use of heteroatom-doped graphene materials and their prospective applications are also proposed.

Chemical Approaches to Carbon-Based Metal-Free Catalysts

Highly active and durable catalysts play a key role in clean energy technologies. However, the high cost, low reserves, and poor stability of noble-metal-based catalysts have hindered the large-scale development of renewable energy. Owing to their low cost, earth abundance, high activity, and excellent stability, carbon-based metal-free catalysts (CMFCs) are promising alternatives to precious-metal-based catalysts. Although many synthetic methods based on solution, surface/interface, solid state, and noncovalent chemistries have been developed for producing numerous CMFCs with diverse structures and functionalities, there is still a lack of effective approaches to precisely control the structures of active sites. Therefore, novel chemical approaches are needed for the development of highly active and durable CMFCs that are capable of replacing precious-metal catalysts for large-scale applications. Herein, a comprehensive and critical review on chemical approaches to CMFCs is given by summarizing important advancements, current challenges, and future perspectives in this emerging field. Through such a critical review, our understanding of CMFCs and the associated synthetic processes will be significantly increased.

Facile Synthesis of SnS2 Nanostructures with Different Morphologies for High-Performance Supercapacitor Applications

SnS₂ is an emerging candidate for an electrode material because of the considerable interlayer spaces in its crystal structures and the large surface area. SnS₂ as a photocatalyst and in lithium ion batteries has been reported. On the other hand, there are only a few reports of their supercapacitor applications. In this study, sheetlike SnS₂ (SL-SnS₂), flowerlike SnS₂ (FL-SnS₂), and ellipsoid-like SnS₂ (EL-SnS₂) were fabricated via a facile solvothermal route using different types of solvents. The results suggested that the FL-SnS₂ exhibited better capacitive performance than the SL-SnS₂ and EL-SnS₂, which means that the morphology has a significant effect on the electrochemical reaction. The FL-SnS₂ displayed higher supercapacitor performance with a high capacity of approximately ∼431.82 F/g at a current density of 1 A/g. The remarkable electrochemical performance of the FL-SnS₂ could be attributed to the large specific surface area and better average pore size. These results suggest that a suitable solvent is appropriate for the large-scale construction of SnS₂ with different morphologies and also has huge potential in the practical applications of high-performance supercapacitors.

Metal-Free Carbon-Based Materials: Promising Electrocatalysts for Oxygen Reduction Reaction in Microbial Fuel Cells

Microbial fuel cells (MFCs) are a promising green approach for wastewater treatment with the simultaneous advantage of energy production. Among the various limiting factors, the cathodic limitation, with respect to performance and cost, is one of the main obstacles to the practical applications of MFCs. Despite the high performance of platinum and other metal-based cathodes, their practical use is limited by their high cost, low stability, and environmental toxicity. Oxygen is the most favorable electron acceptor in the case of MFCs, which reduces to water through a complicated oxygen reduction reaction (ORR). Carbon-based ORR catalysts possessing high surface area and good electrical conductivity improve the ORR kinetics by lowering the cathodic overpotential. Recently, a range of carbon-based materials have attracted attention for their exceptional ORR catalytic activity and high stability. Doping the carbon texture with a heteroatom improved their ORR activity remarkably through the favorable adsorption of oxygen and weaker molecular bonding. This review provides better insight into ORR catalysis for MFCs and the properties, performance, and applicability of various metal-free carbon-based electrocatalysts in MFCs to find the most appropriate cathodic catalyst for the practical applications. The approaches for improvement, key challenges, and future opportunities in this field are also explored.