Showing posts with label graphene. Show all posts
Showing posts with label graphene. Show all posts

Monday, February 23, 2026

Low Emissions Flash Method Upcycles Waste Plastic Into Free Hydrogen

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Researchers have used a low-emissions method to harvest hydrogen and graphene from waste plastics. They say it not only solves environmental problems like plastic pollution and greenhouse gas production, but the value of the graphene by-product could offset the costs of producing hydrogen. Hydrogen is used to power vehicles, generate electricity, and heat our homes and businesses. Hydrogen contains more energy per unit of weight than fossil fuels, which is important from an environmental…..Continue reading

Paul McClure

Source: New Atlas

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Critics:

Efforts to reduce the use of plastics, to promote plastic recycling and to reduce mismanaged plastic waste or plastic pollution have occurred or are ongoing. The first scientific review in the professional academic literature about global plastic pollution in general found that the rational response to the “global threat” would be “reductions in consumption of virgin plastic materials.

Along with internationally coordinated strategies for waste management” – such as banning export of plastic waste unless it leads to better recycling – and describes the state of knowledge about “poorly reversible” impacts which are one of the rationales for its reduction.

Some supermarkets charge their customers for plastic bags, and in some places more efficient reusable or biodegradable materials are being used in place of plastics. Some communities and businesses have put a ban on some commonly used plastic items, such as bottled water and plastic bags. Some non-governmental organizations have launched voluntary plastic reduction schemes like certificates that can be adapted by restaurants to be recognized as eco-friendly among customers.

In January 2019 a “Global Alliance to End Plastic Waste” was created by companies in the plastics industry. The alliance aims to clean the environment from existing waste and increase recycling, but it does not mention reduction in plastic production as one of its targets. Moreover, subsequent reporting has suggested the group is a greenwashing initiative. On 2 March 2022 in Nairobi, representatives of 175 countries pledged to create a legally binding agreement to end plastic pollution.

The agreement should address the full lifecycle of plastic and propose alternatives including reusability. An Intergovernmental Negotiating Committee (INC) that should conceive the agreement by the end of the year 2024 was created. The agreement should facilitate the transition to a circular economy, which will reduce GHG emissions by 25%. Inger Andersen, executive director of UNEP called the decision “a triumph by planet earth over single-use plastics”.

In the lead up to the Assembly, global public opinion on a plastic treaty was surveyed, analysed and reported by The Plastic Free Foundation in partnership with Ipsos and WWF-International. The report identified that nearly 90% of survey participants – over 20,000 adults across 28 countries – believed that having a global plastics treaty will help to effectively address the plastic pollution crisis.

The use of biodegradable plastics has many advantages and disadvantages. Biodegradables are biopolymers that degrade in industrial composters. Biodegradables do not degrade as efficiently in domestic composters, and during this slower process, methane gas may be emitted. There are also other types of degradable materials that are not considered to be biopolymers, because they are oil-based, similar to other conventional plastics.

These plastics are made to be more degradable through the use of different additives, which help them degrade when exposed to UV rays or other physical stressors.Yet biodegradation-promoting additives for polymers have been shown not to significantly increase biodegradation. Although biodegradable and degradable plastics have helped reduce plastic pollution, there are some drawbacks.

One issue concerning both types of plastics is that they do not break down very efficiently in natural environments. There, degradable plastics that are oil-based may break down into smaller fractions, at which point they do not degrade further. A parliamentary committee in the United Kingdom also found that compostable and biodegradable plastics could add to marine pollution because there is a lack of infrastructure to deal with these new types of plastic, as well as a lack of understanding about them on the part of consumers. 

 

For example, these plastics need to be sent to industrial composting facilities to degrade properly, but no adequate system exists to make sure waste reaches these facilities. The committee thus recommended to reduce the amount of plastic used rather than introducing new types of it to the market. Also worth noting is the evolution of new enzymes allowing microorganisms living in polluted locations to digest normal, hard-to-degrade plastic. 

An 2021 study looking for homologs of 95 known plastic-degrading enzymes spanning 17 plastic types found a further 30,000 possible enzymes. Despite their apparent ubiquity, there is no current evidence that these novel enzymes are breaking down any meaningful amount of plastic to reduce pollution.

Chair Cardin Introduces Resolution Calling for International Agreement to Reduce Plastic Pollution United States Senate Committee on Foreign Relations (Press Release) 06:09 Thu, 14 Nov 

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Labels: #WastePlastics #PlasticPollution #ReduceReuseRecycle #EcoFriendly #SustainableLiving #RecyclingAwareness #PlasticWaste #GreenPlanet #ProtectOurOcean #WasteManagement #EnvironmentalImpact #CircularEconomy #SustainableSolutions #PlasticFreeFuture #ConserveNature #Hydrogene #CleanPlanet #StopPlasticPollution #WasteLessLiveMore #Graphene

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Saturday, September 13, 2025

Johns Hopkins Breakthrough Could Make Microchips Smaller Than Ever 

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Johns Hopkins researchers have discovered new materials and a new process that could advance the ever-escalating quest to make smaller, faster and affordable microchips used across modern electronics — in everything from cellphones to cars, appliances to airplanes. The team of scientists has discovered how to create circuits that are so small they’re invisible to the naked eye using a process that is both precise and economical for manufacturing……..Continue reading….

By:  Johns Hopkins University

Source: ScienceDaily

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Critics:

Graphene is a zero-gap semiconductor, because its conduction and valence bands meet at the Dirac points. The Dirac points are six locations in momentum space, on the edge of the Brillouin zone, divided into two non-equivalent sets of three points. The two sets are labeled K and K’. The sets give graphene a valley degeneracy of gv = 2. By contrast, for traditional semiconductors the primary point of interest is generally Γ, where momentum is zero.

Four electronic properties separate it from other condensed matter systems. However, if the in-plane direction is no longer infinite, but confined, its electronic structure would change. They are referred to as graphene nanoribbons. If it is “zig-zag”, the bandgap would still be zero. If it is “armchair”, the bandgap would be non-zero. Graphene’s hexagonal lattice can be regarded as two interleaving triangular lattices.

This perspective was successfully used to calculate the band structure for a single graphite layer using a tight-binding approximation. The cleavage technique led directly to the first observation of the anomalous quantum Hall effect in graphene in 2005, by Geim’s group and by Philip Kim and Yuanbo Zhang. This effect provided direct evidence of graphene’s theoretically predicted Berry’s phase of massless Dirac fermions and the first proof of the Dirac fermion nature of electrons.

These effects had been observed in bulk graphite by Yakov Kopelevich, Igor A. Luk’yanchuk, and others, in 2003–2004. When the atoms are placed onto the graphene hexagonal lattice, the overlap between the pz(Ï€) orbitals and the s or the px and py orbitals is zero by symmetry. The pz electrons forming the Ï€ bands in graphene can therefore be treated independently.

Within this Ï€-band approximation, using a conventional tight-binding model, the dispersion relation (restricted to first-nearest-neighbor interactions only) that produces energy of the electrons with wave vector k iswith the nearest-neighbor (Ï€ orbitals) hopping energy γ0 ≈ 2.8 eV and the lattice constant a ≈ 2.46 Ã…The conduction and valence bands, respectively, correspond to the different signs.

With one pz electron per atom in this model the valence band is fully occupied, while the conduction band is vacant. The two bands touch at the zone corners (the K point in the Brillouin zone), where there is a zero density of states but no band gap. The graphene sheet thus displays a semimetallic (or zero-gap semiconductor) character, although the same cannot be said of a graphene sheet rolled into a carbon nanotube, due to its curvature.

Two of the six Dirac points are independent, while the rest are equivalent by symmetry. In the vicinity of the K-points the energy depends linearly on the wave vector, similar to a relativistic particle. Since an elementary cell of the lattice has a basis of two atoms, the wave function has an effective 2-spinor structure. Graphene’s unit cell has two identical carbon atoms and two zero-energy states: one in which the electron resides on atom A, the other in which the electron resides on atom B.

However, if the two atoms in the unit cell are not identical, the situation changes. Hunt et al. show that placing hexagonal boron nitride (h-BN) in contact with graphene can alter the potential felt at atom A versus atom B enough that the electrons develop a mass and accompanying band gap of about 30 meV [0.03 Electron Volt(eV)].

The mass can be positive or negative. An arrangement that slightly raises the energy of an electron on atom A relative to atom B gives it a positive mass, while an arrangement that raises the energy of atom B produces a negative electron mass. The two versions behave alike and are indistinguishable via optical spectroscopy. An electron traveling from a positive-mass region to a negative-mass region must cross an intermediate region where its mass once again becomes zero.

This region is gapless and therefore metallic. Metallic modes bounding semiconducting regions of opposite-sign mass is a hallmark of a topological phase and display much the same physics as topological insulators. If the mass in graphene can be controlled, electrons can be confined to massless regions by surrounding them with massive regions, allowing the patterning of quantum dots, wires, and other mesoscopic structures.

It also produces one-dimensional conductors along the boundary. These wires would be protected against backscattering and could carry currents without dissipation. Graphene’s unique optical properties produce an unexpectedly high opacity for an atomic monolayer in vacuum, absorbing Ï€Î± ≈ 2.3% of light, from visible to infrared.

Here, α is the fine-structure constant. This is a consequence of the “unusual low-energy electronic structure of monolayer graphene that features electron and hole conical bands meeting each other at the Dirac point… [which] is qualitatively different from more common quadratic massive bands. Based on the Slonczewski–Weiss–McClure (SWMcC) band model of graphite, the interatomic distance, hopping value and frequency cancel when optical conductance is calculated using Fresnel equations in the thin-film limit.

Although confirmed experimentally, the measurement is not precise enough to improve on other techniques for determining the fine-structure constant. Multi-Parametric Surface Plasmon Resonance was used to characterize both thickness and refractive index of chemical-vapor-deposition (CVD)-grown graphene films.

The measured refractive index and extinction coefficient values at 670 nm (6.7×10−7 m) wavelength are 3.135 and 0.897, respectively. The thickness was determined as 3.7Ã… from a 0.5mm area, which agrees with 3.35Ã… reported for layer-to-layer carbon atom distance of graphite crystals. The method can be further used also for real-time label-free interactions of graphene with organic and inorganic substances.

Furthermore, the existence of unidirectional surface plasmons in the nonreciprocal graphene-based gyrotropic interfaces has been demonstrated theoretically. By efficiently controlling the chemical potential of graphene, the unidirectional working frequency can be continuously tunable from THz to near-infrared and even visible.

 Particularly, the unidirectional frequency bandwidth can be 1– 2 orders of magnitude larger than that in metal under the same magnetic field, which arises from the superiority of extremely small effective electron mass in graphene.

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A New, Open Source Text-To-Speech Model Called Dia Has Arrived To Challenge ElevenLabs, OpenAI and More

VentureBeat made with Midjourney A two-person startup by the name of  Nari Labs  has introduced Dia , a 1.6 billion parameter text-to-speech...