Tailored Nanoarchitectures: MoS₂/Graphene and MoS/Graphene Oxide Thin Films via Liquid-Liquid Interfacial Route.

The nanostructured assembly of different two-dimensional (2D) materials in specific organization is crucial for developing materials with synergistic properties. In this study, we present a general methodology to prepare thin, transparent and self-assembled films of 2D/2D composites based on molybdenum sulfide (MoS)/graphene oxide (GO) or MoS/reduced graphene oxide (rGO), through the liquid/liquid interfacial route. Different nanoarchitectures are obtained by changing simple experimental parameters during the thin film preparation steps.

Platinum Nanoparticles Supported by Carbon Nanotubes: Improvement in electrochemical sensor performance for caffeine determination.

Platinum nanoparticles supported by carbon nanotubes were obtained by a simple chemical route and used for preparation of electrochemical sensor towards caffeine determination. Carbon nanotubes were used before and after an acid treatment, yielding two different materials. Morphological and structural characterization of these materials showed platinum nanoparticles (size around 12 nm) distributed randomly along carbon nanotubes.

Influence of Defects and Charges on the Colloidal Stabilization of Graphene in Water.

Mastering graphene preparation is an essential step to its integration into practical applications. For large-scale purposes, full graphite exfoliation appears as a suitable route for graphene production. However, it requires overpowering attractive van der Waals forces demanding large energy input, with the risk of introducing defects in the material.

Probing the Electronic Structure of Prussian Blue and Analog Films by Photoemission and Electron Energy Loss Spectroscopies.

X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS) were employed to characterize the electronic properties of Prussian blue (PB) and its analogs when electrodeposited over metal-decorated carbon nanotubes (CNTs). Through an investigation of the influence of carbon nanotubes (CNTs) and preparation conditions on the electronic structure, valuable insights were obtained regarding their effects on electrochemical properties. XPS analysis enabled the probing of the chemical composition and oxidation states of the film materials, unveiling synthesis-driven variations in their electronic properties.

Nanoarchitected graphene/copper oxide nanoparticles/MoS ternary thin films as highly efficient electrodes for aqueous sodium-ion batteries.

Sodium-ion batteries (SIBs) operating in aqueous electrolyte are an emerging technology that promises to be safer, cheaper, more sustainable and more efficient than their lithium-based counterparts. One of the great challenges associated with this technology is the development of advanced materials with high specific capacity to be used as electrodes. Herein, we describe an ingenious strategy to prepare unprecedented tri-component nanoarchitected thin films with superior performance when applied as anodes in aqueous SIBs.

One-step selective layer assemble: A versatile approach for the development of a SARS-CoV-2 electrochemical immunosensor.

The appearance of new viruses and diseases has made the development of rapid and reliable diagnostic tests crucial. In light of it, we proposed a new method for assembling an electrochemical immunosensor, based on a one-step approach for selective layer formation. For this purpose, a mixture containing the immobilizing agent (polyxydroxybutyrate, PHB) and the recognition element (antibodies against SARS-CoV-2 nucleocapsid protein) was prepared and used to modify a screen-printed carbon electrode with electrodeposited graphene oxide, for the detection of SARS-CoV-2 nucleocapsid protein (N-protein).

A versatile 3D printed multi-electrode cell for determination of three COVID-19 biomarkers.

3D-printing has shown an outstanding performance for the production of versatile electrochemical devices. However, there is a lack of studies in the field of 3D-printed miniaturized settings for multiplex biosensing. In this work, we propose a fully 3D-printed micro-volume cell containing six working electrodes (WEs) that operates with 250 μL of sample.

Graphene-Binding Peptide in Fusion with SARS-CoV-2 Antigen for Electrochemical Immunosensor Construction.

The development of immunosensors to detect antibodies or antigens has stood out in the face of traditional methods for diagnosing emerging diseases such as the one caused by the SARS-CoV-2 virus. The present study reports the construction of a simplified electrochemical immunosensor using a graphene-binding peptide applied as a recognition site to detect SARS-CoV-2 antibodies. A screen-printed electrode was used for sensor preparation by adding a solution of peptide and reduced graphene oxide (rGO).

Introduction to celebrating Latin American talent in chemistry.

In celebration of the excellence and breadth of Latin American research achievements across the chemical sciences, we are delighted to present an introduction to the themed collection, Celebrating Latin American talent in chemistry.

Liquid-liquid interfaces: a unique and advantageous environment to prepare and process thin films of complex materials.

Thin film technology is pervasive for many fields with high impact in our daily lives, which makes processing materials such as thin films a very important subject in materials science and technology. However, several paramount materials cannot be prepared as thin films through the well-known and consolidated deposition routes, which strongly limits their applicability. This is particularly noticeable for multi-component and complex nanocomposites, which present unique properties due to the synergic effect between the components, but have several limitations to be obtained as thin films, mainly if homogeneity and transparence are required.

A simple enzymeless approach for Paraoxon determination using imidazole-functionalized carbon nanotubes.

This work describes the application of a glassy carbon electrode (GCE) modified with imidazole functionalized carbon nanotubes (CNT-H-IMZ) for Paraoxon (PX) determination in samples of commercial, fresh and 100% orange juice. Homemade multi-walled CNTs were treated according to the Hummers procedure to oxidize graphite and later chemically functionalized with imidazole groups. Modified electrodes with CNT-H-IMZ presented a high peak current of PX reduction and an electrocatalytic effect in comparison to the other electrodes.

A black phosphorus-based cathode for aqueous Na-ion batteries operating under ambient conditions.

We present the unprecedented application of a black phosphorus-based nanocomposite as an electrode for aqueous Na-ion batteries under ambient conditions. An impressive specific capacity of up to 200 mA h g was reached after 50 cycles in a NaCl aqueous solution used as a supporting electrolyte. Post-characterization indicated the integrity of the black phosphorus.

Molybdenum-based two-dimensional materials: Synthesis, dispersion, exfoliation and thin film deposition.

We report a simple and effective route to synthesize, disperse, exfoliate and process different molybdenum-based 2-dimensional (2D) materials. Starting from a reaction between ammonium molybdate and ammonium sulfide solutions, a powder consisting of a mixture between amorphous molybdenum oxide and sulfide is obtained. By tuning the atmosphere and the temperature, different compositions can be prepared by thermal treatment of this sample: heat treatments in ambient atmosphere produce MoO with different morphologies, controllable according to the chosen temperature.

A new approach for the achievement of stable aqueous dispersions of carbon nanotubes.

A novel methodology to prepare stable aqueous dispersions of raw single- and multi-walled carbon nanotubes is reported, based on dispersions previously prepared in tetrahydrofuran containing a phenol that donates electrons to nanotubes and provides colloidal stability through electrostatic repulsion. A proposed mechanism for the stabilization of the dispersions is presented. Conductive and transparent thin films are prepared through a liquid/liquid interfacial route starting from these dispersions.

Molecular orientation and femtosecond charge transfer dynamics in transparent and conductive electrodes based on graphene oxide and PEDOT:PSS composites.

The conducting polymer, poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS), is certainly one of the most important substitute materials for indium tin oxide in organic devices. Its metallic conductivity and transmittance bring favorable perspectives for organic photovoltaic applications. Although graphene oxide (GO) is not a good conductor, it can form high-quality thin films and can be transparent, and additionally, GO is an inexpensive material and can be easily synthesized.

Facile room temperature synthesis of large graphene sheets from simple molecules.

The largest graphene sample obtained through a chemical reaction under ambient conditions (temperature and pressure), using simple molecules such as benzene or -hexane as precursors, is reported. Starting from a heterogeneous reaction between solid iron chloride and the molecular precursor (benzene and -hexane) at a water/oil interface, graphene sheets with micrometric lateral size are obtained as a film deposited at the liquid/liquid (L/L) interface. The pathway involving the cyclization and aromatization of -hexane to benzene at the L/L interface, and the sequence of conversion of benzene to biphenyl and biphenyl to condensed rings (which originates the graphene structures) was followed by different characterization techniques and a mechanistic proposal is presented.

Ultrafast interface charge transfer dynamics on P3HT/MWCNT nanocomposites probed by resonant Auger spectroscopy.

The interfacial electronic structure and charge transfer dynamics of poly-3-hexylthiophene (P3HT) and multi-walled carbon nanotube (Fe-MWCNT) nanocomposites were investigated by near-edge X-ray absorption fine structure (NEXAFS) and resonant Auger (RAS) spectroscopies around the sulfur K-edge. Nanocomposites with 5 wt% (P3HT/Fe-MWCNT-5%) and 10 wt% (P3HT/Fe-MWCNT-10%) of Fe-MWCNT species were prepared and compared with pristine P3HT film. The quantitative NEXAFS analysis shows a strong π-π interchain interaction of the pristine P3HT polymer film, which is reduced by the presence of the Fe-MWCNT.

Electrostatic stabilization of multi-walled carbon nanotubes dispersed in nonaqueous media.

Dispersing carbon nanotubes is an easy and low-cost way to manipulate these solids and allows the preparation of more complex materials or devices, so it is fundamental for further uses that these dispersions have controlled properties and high colloidal stability. In this work we report the spontaneous electrical charge build-up in pristine multi-walled carbon nanotubes dispersed in common organic solvents such as chloroform and tetrahydrofuran and the achievement of dispersions stable for long periods without adding passivant agents or functional groups on nanotubes surface. Results from electrokinetics, homo- and heterocoagulation provided macroscopic evidences that carbon nanotubes acquire electric charges after dispersion in some organic liquids and we confirmed this process by measuring in situ Raman spectra of the nanotubes dispersions with higher surface electric potentials.

Nonenzymatic electrochemical sensor based on imidazole-functionalized graphene oxide for progesterone detection.

The modification of electrode surfaces has been the target of study for many researchers in order to improve the analytical performance of electrochemical sensors. Herein, the use of an imidazole-functionalized graphene oxide (GO-IMZ) as an artificial enzymatic active site for voltammetric determination of progesterone (P4) is described for the first time. The morphology and electrochemical performance of electrode modified with GO-IMZ were characterized by scanning electron microscopy and cyclic voltammetry, respectively.

Photoanode for Aqueous Dye-Sensitized Solar Cells based on a Novel Multicomponent Thin Film.

Most of the dye-sensitized solar cells (DSSCs) developed so far use organic electrolytes and water-sensible sensitizers. The search for aqueous DSSCs, a promising technology for solar-energy conversion, implies finding materials that are stable in aqueous solution. In this study, Prussian blue (PB) was utilized as an innovative sensitizer in a photoanode for DSSCs and a novel synthetic approach to a carbon nanotubes/TiO /PB nanocomposite thin film was developed.

Direct and one-step synthesis of polythiophene/gold nanoparticles thin films through liquid/liquid interfacial polymerization.

This work demonstrates a simple and one-step synthesis of polythiophene/gold nanoparticles (PT/Au) nanocomposite thin films, through a liquid-liquid (L/L) interfacial polymerization route. Starting from an aqueous solution of tetrachloroauric acid (acting both as metallic gold source and oxidizing agent to start the oxidative polymerization of thiophene), and a solution of thiophene in n-hexane, a biphasic L/L system was originated. In the following, the interface acted as a meeting-point for the reactants, and the polymerization reaction took place, leading to self-assembled PT/Au film between the two immiscible liquids.

Highly Conducting, Sustainable, Nanographitic Rubber Composites.

Environmentally friendly multifunctional rubber composites are reported. Graphitic nanocarbon (NC) deriving from cracking of biogas (methane/carbon dioxide) and natural rubber extracted directly from the tree are the two components of these composites produced via latex technology. While maintaining and enhancing the intrinsic thermal and mechanical characteristics of rubber, the presence of NC shows a significant improvement on the electrical response.

Air stable black phosphorous in polyaniline-based nanocomposite.

The greatest challenge regarding black phosphorus (BP) comes as a result of its fast degradation when exposed to ambient conditions, which has overshadowed its applications. Herein, we report a simple and efficient route towards overcoming BP deterioration by preparing a nanocomposite with the conducting polymer polyaniline (PANI). The liquid/liquid interfacial method was employed to produce transparent, freestanding and transferable thin film of BP covered by PANI, with high stability under ambient atmosphere, up to 60 days.

Design of a new nanocomposite between bismuth nanoparticles and graphene oxide for development of electrochemical sensors.

This study describes a new route for preparation of a nanocomposite between graphene oxide (GO) and bismuth nanoparticles (BiNPs) and its evaluation as modifier electrode for development of electrochemical sensors. BiNPs were synthesized under ultrasound conditions using Bi(NO) as metal precursor and ascorbic acid (AA) as reducing agent/passivating. Some experimental parameters of BiNPs synthesis such as Bi:AA molar ratio and reaction time were conducted aiming the best voltammetric performance of the sensor.