Multifaceted role of HO in the solvothermal synthesis of green-emitting nitrogen-doped graphene quantum dots.

Fluorescent nitrogen-doped carbon dots (N-GQDs) with long-wavelength emission properties are of increased interest for technological applications. They are widely synthesized through the solvothermal treatment of graphene oxide (GO) using ,-dimethylformamide (DMF) as a cleaving and doping agent. However, this process simultaneously generates undesired interfering blue-emissive by-products.

Hybrids of Deep HOMO Organic Cyanoacrylic Acid Dyes and Graphene Nanomaterials for Water Splitting Photoanodes.

Dye-sensitization is a promising strategy to improve the light absorption and photoactivity abilities of wide-bandgap semiconductors, like TiO. For effective water-splitting photoanodes with no sacrificial agents, the electrochemical potential of the dye must exceed the thermodynamic threshold needed for the oxygen evolution reaction. This study investigates two promising organic cyanoacrylic dyes, designed to meet that criterion by means of theoretical calculations.

Nanocellulose: The Ultimate Green Aqueous Dispersant for Nanomaterials.

Nanocellulose, a nanoscale derivative from renewable biomass sources, possesses remarkable colloidal properties in water, mechanical strength, and biocompatibility. It emerges as a promising bio-based dispersing agent for various nanomaterials in water. This mini-review explores the interaction between cellulose nanomaterials (nanocrystals or nanofibers) and water, elucidating how this may enable their potential as an eco-friendly dispersing agent.

Oil-in-Water Pickering Emulsions Stabilized with Nanostructured Biopolymers: A Venue for Templating Bacterial Cellulose.

Pickering emulsions (PEs) differ from conventional emulsions in the use of solid colloidal particles as stabilizing agents instead of traditional amphiphilic molecules. Nanostructured biopolymers (NBs) emerge as a promising alternative for PE stabilization owing to their remarkable biocompatibility, abundant availability, and low cost. To explore this potential, a study is herein presented, in which cellulose nanocrystals (CNCs), both type I and type II allomorphs, and chitin nanocrystals (ChNCs) were used for stabilizing oil-in-water PEs prepared by the use of ultrasound.

Preparation of Cellulose Nanocrystals: Controlling the Crystalline Type by One-Pot Acid Hydrolysis.

Cellulose nanocrystals (CNCs) have aroused increasing interest owing to their renewable origin and excellent properties derived from their size and morphology. Based on their chain orientation, CNCs can be prepared as two main allomorphs (I or II). However, achieving pure CNC allomorphs still requires enhanced control on the CNCs synthesis process and improved understanding of the involved reaction parameters.

Effect of nanocellulose polymorphism on electrochemical analytical performance in hybrid nanocomposites with non-oxidized single-walled carbon nanotubes.

Two cellulose nanocrystals/single-walled carbon nanotube (CNC/SW) hybrids, using two cellulose polymorphs, were evaluated as electrochemical transducers: CNC type I (CNC-I/SW) and CNC type II (CNC-II/SW). They were synthesized and fully characterized, and their analytical performance as electrochemical sensors was carefully studied. In comparison with SWCNT-based and screen-printed carbon electrodes, CNC/SW sensors showed superior electroanalytical performance in terms of sensitivity and selectivity, not only in the detection of small metabolites (uric acid, dopamine, and tyrosine) but also in the detection of complex glycoproteins (alpha-1-acid glycoprotein (AGP)).

Nanoscale Charge Density and Dynamics in Graphene Oxide.

Graphene oxide (GO) is widely used as a component in thin film optoelectronic device structures for practical reasons because its electronic and optical properties can be controlled. Progress critically depends on elucidating the nanoscale electronic structure of GO. However, direct experimental access is challenging because of its disordered and nonconductive character.

Synthesis and Processing of Nanomaterials Mediated by Living Organisms.

Nanomaterials offer exciting properties and functionalities. However, their production and processing frequently involve complex methods, cumbersome equipment, harsh conditions, and hazardous media. The capability of organisms to accomplish this using mild conditions offers a sustainable, biocompatible, and environmentally friendly alternative.

Waterborne Graphene- and Nanocellulose-Based Inks for Functional Conductive Films and 3D Structures.

In the vast field of conductive inks, graphene-based nanomaterials, including chemical derivatives such as graphene oxide as well as carbon nanotubes, offer important advantages as per their excellent physical properties. However, inks filled with carbon nanostructures are usually based on toxic and contaminating organic solvents or surfactants, posing serious health and environmental risks. Water is the most desirable medium for any envisioned application, thus, in this context, nanocellulose, an emerging nanomaterial, enables the dispersion of carbon nanomaterials in aqueous media within a sustainable and environmentally friendly scenario.

Cobalt-Doped ZnO Nanorods Coated with Nanoscale Metal-Organic Framework Shells for Water-Splitting Photoanodes.

Developing highly efficient and stable photoelectrochemical (PEC) water-splitting electrodes via inexpensive, liquid phase processing is one of the key challenges for the conversion of solar energy into hydrogen for sustainable energy production. ZnO represents one the most suitable semiconductor metal oxide alternatives because of its high electron mobility, abundance, and low cost, although its performance is limited by its lack of absorption in the visible spectrum and reduced charge separation and charge transfer efficiency. Here, we present a solution-processed water-splitting photoanode based on Co-doped ZnO nanorods (NRs) coated with a transparent functionalizing metal-organic framework (MOF).

Laser-Deposited Carbon Aerogel Derived from Graphene Oxide Enables NO-Selective Parts-per-Billion Sensing.

Laser-deposited carbon aerogel is a low-density porous network of carbon clusters synthesized using a laser process. A one-step synthesis, involving deposition and annealing, results in the formation of a thin porous conductive film which can be applied as a chemiresistor. This material is sensitive to NO compared to ammonia and other volatile organic compounds and is able to detect ultra-low concentrations down to at least 10 parts-per-billion.

Carbon Nanotube Film Electrodes with Acrylic Additives: Blocking Electrochemical Charge Transfer Reactions.

Carbon nanotubes (CNTs) processed into conductive films by liquid phase deposition technologies reveal increasing interest as electrode components in electrochemical device platforms for sensing and energy storage applications. In this work we show that the addition of acrylic latex to water-based CNT inks not only favors the fabrication of stable and robust flexible electrodes on plastic substrates but, moreover, sensitively enables the control of their electrical and electrochemical transport properties. Importantly, within a given concentration range, the acrylic additive in the films, being used as working electrodes, effectively blocks undesired faradaic transfer reactions across the electrode-electrolyte interface while maintaining their capacitance response as probed in a three-electrode electrochemical device configuration.

Bottom-Up Synthesized MoS Interfacing Polymer Carbon Nanodots with Electrocatalytic Activity for Hydrogen Evolution.

The preparation of an MoS -polymer carbon nanodot (MoS -PCND) hybrid material was accomplished by employing an easy and fast bottom-up synthetic approach. Specifically, MoS -PCND was realized by the thermal decomposition of ammonium tetrathiomolybdate and the in situ complexation of Mo with carboxylic acid units present on the surface of PCNDs. The newly prepared hybrid material was comprehensively characterized by spectroscopy, thermal means, and electron microscopy.

In-Situ Growth and Immobilization of CdS Nanoparticles onto Functionalized MoS : Preparation, Characterization and Fabrication of Photoelectrochemical Cells.

A facile strategy for the controllable growth of CdS nanoparticles at the periphery of MoS en route the preparation of electron donor-acceptor nanoensembles is developed. Precisely, the carboxylic group of α-lipoic acid, as addend of the modified MoS obtained upon 1,2-dithiolane functionalization, was employed as anchor site for the in situ preparation and immobilization of the CdS nanoparticles in an one-pot two-step process. The newly prepared MoS /CdS hybrid material was characterized by complementary spectroscopic, thermal and microscopy imaging means.

Chemical Postdeposition Treatments To Improve the Adhesion of Carbon Nanotube Films on Plastic Substrates.

The robust adhesion of single-walled carbon nanotubes (SWCNTs) to plastic substrates is a key issue toward their use in flexible electronic devices. In this work, semitransparent SWCNT films were prepared by spray-coating on two different plastic substrates, specifically poly(ethylene terephthalate) and poly(vinylidene fluoride). The deposited SWCNT films were treated by dipping in suitable solvents separately, namely, 53% nitric acid (HNO) and -methyl pyrrolidone.

Carbon Nanofoam Supercapacitor Electrodes with Enhanced Performance Using a Water-Transfer Process.

Carbon nanofoam (CNF) is a highly porous, amorphous carbon nanomaterial that can be produced through the interaction of a high-fluence laser and a carbon-based target material. The morphology and electrical properties of CNF make it an ideal candidate for supercapacitor applications. In this paper, we prepare and characterize CNF supercapacitor electrodes through two different processes, namely, a direct process and a water-transfer process.

Unique Properties and Behavior of Nonmercerized Type-II Cellulose Nanocrystals as Carbon Nanotube Biocompatible Dispersants.

Nanocellulose is increasingly being investigated as a paradigm of a sustainable nanomaterial because of its extraordinary physical and chemical properties, together with its renewable nature and worldwide abundance. The rich structural diversity of cellulose materials is represented by different crystalline allomorphs, from which types I and II stand out. While type I is naturally and ubiquitously present, type II is man-made and requires harsh and caustic synthesis conditions such as the so-called mercerization process.

Nanoscale J-aggregates of poly(3-hexylthiophene): key to electronic interface interactions with graphene oxide as revealed by KPFM.

The nanoscale aggregate structure of conjugated polymers critically determines the performance of organic thin film optoelectronic devices. Their impact on electronic interface interactions with adjacent layers of graphene, widely reported to improve the device characteristics, yet remains an open issue, which needs to be addressed by an appropriate benchmark system. Here, we prepared discrete ensembles of poly(3-hexylthiophene) nanoparticles and graphene oxide sheets (P3HTNPs-GO) with well-defined aggregate structures of either J- or H-type and imaged their photogenerated charge transfer dynamics across their interface by Kelvin probe force microscopy (KPFM).

A tool box to ascertain the nature of doping and photoresponse in single-walled carbon nanotubes.

The effect of doping on the electronic properties in bulk single-walled carbon nanotube (SWCNT) samples is studied for the first time using a new in situ Raman spectroelectrochemical method, and further verified by DFT calculations and photoresponse. We use p-/n-doped SWCNTs prepared by diazonium reactions as a versatile chemical strategy to control the SWCNT behavior. The measured and calculated data testify an acceptor effect of 4-aminobenzenesulfonic acid (p-doping), and a donor effect (n-doping) in the case of benzyl alcohol.

Integrating Water-Soluble Polythiophene with Transition-Metal Dichalcogenides for Managing Photoinduced Processes.

Transition-metal dichalcogenides (TMDs) attract increased attention for the development of donor-acceptor materials enabling improved light harvesting and optoelectronic applications. The development of novel donor-acceptor nanoensembles consisting of poly(3-thiophene sodium acetate) and ammonium functionalized MoS and WS was accomplished, while photoelectrochemical cells were fabricated and examined. Attractive interactions between the negatively charged carboxylate anion on the polythiophene backbone and the positively charged ammonium moieties on the TMDs enabled in a controlled way and in aqueous dispersions the electrostatic association of two species, evidenced upon titration experiments.

Interfacing Transition Metal Dichalcogenides with Carbon Nanodots for Managing Photoinduced Energy and Charge-Transfer Processes.

Exfoliated semiconducting MoS and WS were covalently functionalized with 1,2-dithiolane-modified carbon nanodots (CNDs). The newly synthesized CND-MoS and CND-WS hybrids were characterized by spectroscopic, thermal, and electron microscopy imaging methods. Based on electronic absorption and fluorescence emission spectroscopy, modulation of the optoelectronic properties of TMDs by interfacing with CNDs was accomplished.