Green Carbon Nanostructures for Functional Composite Materials

Electrochemical biosensor based on copper sulfide/reduced graphene oxide/glucose oxidase construct for glucose detection

Due to the current increase in the number of people suffering from diabetes worldwide, how to monitor the blood glucose level in the human body has become an urgent problem to be solved nowadays. The electrochemical sensor method can be used for real-time glucose monitoring due to its advantages of real-time monitoring capability and high sensitivity. Reduced graphene oxide (rGO) has great potential for application in the field of sensors due to its advantages of large specific surface area, high stability, and good electrical and thermal conductivity. Meanwhile, the synergistic effect between two-dimensional transition metal sulfides and graphene can improve the electrochemical performance of materials due to their similar mechanical flexibility and strength. This article uses flake graphite, copper sulfate, and glucose oxidase (GOx) as raw materials to prepare CuS/rGO/GOx/GCE electrodes, and explores the performance of electrode electrocatalysis for glucose. The results showed that the prepared sensor was characterized by a low detection limit (1.75 nM) and a wide linear range (0.1-100 mM) for glucose detection, displaying a good overall detection performance, and its sensing mechanism and dynamic process were also investigated. In addition, the sensor has outstanding selectivity, anti-interference, repeatability, reproducibility and practicality.

N, F Co-Doped Carbon Derived from Spent Bleaching Earth Waste as Oxygen Electrocatalyst Support

Affordable nitrogen and fluorine co-doped carbon nanostructure was prepared from the hazardous industrial waste of edible oil refinery, spent bleaching earth (SBE), and used as raw material for obtaining high-performance non-noble metal bifunctional oxygen electrocatalysts. Waste SBE contains 35 % residue non-saturated oil as a carbon source and the assistance of montmorillonite (MMT) as the template. This study converts waste SBE into a fluorine-doped carbon nanostructure through a pyrolysis process followed by removing the aluminosilicate layers of the MMT by HF etching. Furthermore, the impregnation of the support with Co and Fe nitrates readily gives rise to N, F co-doped carbon (NFC) electrocatalysts, as confirmed by XPS analysis. Electrochemical results evidenced that the Co-NFC catalyst proved to be a valuable bifunctional competitor for oxygen reduction reaction and oxygen evolution reaction in alkaline media, showing activity in both reactions and superior stability compared with the Fe-NFC catalyst in accelerated tests. This work offers a straightforward, economical, and eco-friendly strategy for designing N, F co-doped carbon-based electrocatalysts for oxygen reactions in electrochemical devices.

Preparation and characterization of lignin-derived carbon aerogels

Lignin is considered a valuable renewable resource for building new chemicals and materials, particularly resins and polymers. The aromatic nature of lignin suggests a synthetic route for synthesizing organic aerogels (AGs) similar to the aqueous polycondensation of resorcinol with formaldehyde (FA). The structure and reactivity of lignin largely depend on the severity of the isolation method used, which challenges the development of new organic and carbon materials. Resorcinol aerogels are considered a source of porous carbon material, while lignin-based aerogels also possess great potential for the development of carbon materials, having a high carbon yield with a high specific surface area and microporosity. In the present study, the birch hydrolysis lignin and organosolv lignin extracted from pine were used to prepare AGs with formaldehyde, with the addition of 5-methylresorcinol in the range of 75%-25%, yielding monolithic mesoporous aerogels with a relatively high specific surface area of up to 343.4 m2/g. The obtained lignin-based AGs were further used as raw materials for the preparation of porous carbon aerogels (CAs) under well-controlled pyrolysis conditions with the morphology, especially porosity and the specific surface area, being dependent on the origin of lignin and its content in the starting material.

MXenes vs. clays: emerging and traditional 2D layered nanoarchitectonics

Although MXene materials are considered an emerging research topic, they are receiving considerable interest because, like metals and graphene, they are good electronic conductors but with the particularity that they have a marked hydrophilic character. Having a structural organization and properties close to those of clay minerals (natural silicates typically with a lamellar morphology), they are sometimes referred to as "conducting clays" and exhibit colloidal, surface and intercalation properties also similar to those of clay minerals. The present contribution aims to inform and discuss the nature of MXenes in comparison with clay phyllosilicates, taking into account their structural analogies, outstanding surface properties and advanced applications. The current in-depth understanding of clay minerals may represent a basis for the future development of MXene-derived nanoarchitectures. Comparative examples of the preparation, and studies on the properties and applications of various nanoarchitectures based on clays and MXenes have been included in the present work.

Reduced graphene oxide: Biofabrication and environmental applications

Green synthesis of high-quality reduced graphene oxide (rGO) from agro-industrial waste resources remains attractive owing to its outstanding environmental benefits. The remarkable properties of rGO include excellent morphology, uniform particle size, good optical properties, high conductivity, nontoxicity, and extraordinary chemical stability. Traditional methods for the synthesis of rGO nanomaterials involve several chemical reactions including oxidation, carbonization, toxic solvent, and pyrolysis which produce harmful byproducts. Green preparation of rGO is an emerging area of research in graphene technology which is cost-effective and sustainable in the procedure. Owing to the uniform particle rGO particle size, these smart nanomaterials have wide applicability, including in metal ions and pollutant sensing and adsorption, photocatalysis, optoelectrical devices, medical diagnosis, and drug delivery. Here we review the physicochemical properties of rGO, the biowaste sources and green methods of rGO synthesis, and the diverse applications of rGO, including in water purification and the biomedical fields. With this review, covering more than 200 research articles published on rGO in the last eight years ending in 2022, we aim to provide a quick guide for researchers seeking up-to-date information on the properties, production, and applicability of rGO, with special attention to rGO applications in water purification and the biomedical fields.

Molecular and Macromolecular Interactions of Carbon-Based Nanostructures

The interactions of molecules and macromolecules with carbon nanostructures such as carbon dots, carbon nanotubes, graphene, graphene oxide, and fullerenes, have been stimulating the interest of the researchers working on the preparation, functionalization, properties and applications of carbon-based nanomaterials [...].