Facile green synthesis of nitrogen-doped porous carbon and its use for electrocatalysis towards nitrobenzene and hydrazine

An ultra-sensitive electrochemical sensor of Ni/Fe-LDH toward nitrobenzene with the assistance of surface functionalization engineering

Hypersensitive detection of organic pollutions with high toxicity in drinking water always keeps its challenge in electroanalysis due to their low concentration and electrochemical redox inert. In this work, a novel nanomaterial modified electrode for the sensitive detection of nitrobenzene (NB) is presented, based on environmental friendly and cost-effective Ni/Fe layered double hydroxides functionalized with sodium dodecyl sulfate (Ni/Fe(SDS)-LDH). Such 2D layered composites were prepared and used to improve the sensitivity for NB detection, due to its good catalytic activity for NB reduction. Besides, the proposed electrode shows a remarkably promoted sensitivity to NB compared to Ni/Fe-LDHs modified one. It is because that the surface modifier SDS can provide more adsorption sites to significantly improve the adsorption of NB, which has been confirmed by the adsorption experiment and the characterization of Fourier transform infrared spectroscopy (FTIR). As a result, an impressive sensing behaviour is achieved at the proposed Ni/Fe(SDS)-LDHs modified electrode with a sensitivity of 15.79 μA μM^-1 cm^-2. This work provides a promising way to build more advanced nanomaterials to electrochemical detection of organic pollution based on energetically synergizing of adsorption by surface functionalization engineering.

Heteroatom-Doped Carbon Materials for Hydrazine Oxidation

The key in designing efficient direct liquid fuel cells (DLFCs), which can offer some solutions to society's grand challenges associated with sustainability and energy future, currently lies in the development of cost-effective electrocatalysts. Among the many types of fuel cells, direct hydrazine fuel cells (DHFCs) are of particular interest, especially due to their high theoretical cell voltages and clean emission. However, DHFCs currently use noble-metal-based electrocatalysts, and the scarcity and high cost of noble metals are hindering these fuel cells from finding large-scale practical applications. In order to replace noble-metal-based electrocatalysts with sustainable ones and help DHFCs become widely usable, great efforts are being made to develop stable heteroatom (e.g., B, N, O, P and S)-doped carbon electrocatalysts, the activities of which are comparable to, or better than, those of noble metals. Here, the recent research progress and the advancements made on the development of heteroatom-doped carbon materials, their general properties, their electrocatalytic activities toward the HzOR, and their dopant- and structure-related electrocatalytic properties for the HzOR are summarized. Perspectives on the different directions that the research endeavors in this field need to take in the future and the challenges associated with DHFCs are included.

High oxygen-reduction activity and durability of nitrogen and sulfur dual doped porous carbon microspheres

Nitrogen and sulfur co-doped monodisperse carbon microspheres (NS-CMSs) have been successfully synthesized as a new kind of outstanding metal-free ORR catalyst through a one-pot solvothermal reaction. The as-synthesized heteroatom-doped CMSs have been systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) and by using Raman spectra and nitrogen adsorption and desorption isotherms. Compared with the commercially available 20 wt% Pt/C catalyst, the as-prepared NS-CMSs showed a much better tolerance toward methanol crossover and long-term operation stability for ORR in an alkaline medium.

Integration of inorganic nanostructures with polydopamine-derived carbon: tunable morphologies and versatile applications

Polydopamine (PDA), a mussel adhesive-inspired biomimetic polymer, has attracted tremendous attention owing to its extremely versatile adhesion properties, facile aqueous coating process, capability of self-assembly to form nanostructures, and abundant surface functional groups for secondary modification. PDA is also a fantastic carbon source because it gives nitrogen (N)-doped graphite-like carbon in high yield, and the carbonized PDA (C-PDA) thin coatings have similar properties to those of N-doped multilayered graphene, i.e., they exhibit high electrical conductivity, and good electrochemical and mechanical properties. In comparison with other carbon sources, an outstanding feature of PDA lies in its ease of integration with inorganic nanostructures and capability for easy tailoring the structure and morphology of the resultant composite nanostructures. In this article, different routes for the preparation of C-PDA-based composite nanostructures, such as carbon/metal oxide and carbon/Si hollow, mesoporous, core-shell, yolk-shell nanostructures, are introduced with typical examples. The structures, morphologies and properties of the C-PDA-based composite nanostructures are also reviewed, and their potential applications in various engineering fields, such as energy storage, solar water splitting, flexible electronics, catalysis, sensing and environmental engineering, are highlighted. Finally a future outlook for this fascinating composite-nanostructure enabler is also presented.

Preparation of catalytic films of the Au nanoparticle-carbon composite tubular arrays

Catalytic films comprising the arrayed mesoporous and big-inner-diameter carbon nanotubes embedded with high density Au nanoparticles were prepared through a template-directed carbonization route.

Sensitive impedimetric biosensor based on duplex-like DNA scaffolds and ordered mesoporous carbon nitride for silver(I) ion detection

This study demonstrates a new, unlabeled immobilized DNA-based biosensor with ordered mesoporous carbon nitride material (MCN) for the detection of Ag(+) by electrochemical impedance spectroscopy (EIS) with [Fe(CN)6](4-/3-) as the redox couple. The unlabeled immobilized DNA initially formed the hairpin-like structure through hybridization with the probe, and then changed to duplex-like structure upon interaction with Ag(+) in solution to form a C-Ag(+)-C complex at electrode surface. As a result, the interfacial charge-transfer resistance of the electrode towards the [Fe(CN)6](4-/3-) redox couple was changed. Thus, a declined charge transfer resistance (Rct) was obtained, corresponding to Ag(+) concentration. MCN provide an excellent platform for DNA immobilization and faster electron transfer. Impedance data were analyzed with the help of Randles equivalent circuit. The lower detection limit of the biosensor for Ag(+) is 5 × 10(-11) M with good specificity. All results showed that this novel approach provides a reliable method for Ag(+) detection with sensitivity and specificity, potentially useful for practical applications. Moreover, other DNA detection methods for more heavy metals may be obtained from this idea and applied in the environmental field.

Nitrogen-doped porous carbon foams prepared from mesophase pitch through graphitic carbon nitride nanosheet templates

A scalable and facile method was developed to synthesize nitrogen-doped porous carbon foams (NPCFs) using graphitic carbon nitride (g-C₃N₄) nanosheets as hard templates through the calcination of mesophase pitch.