what is Graphene

what is Graphene?

What you need to know about Graphene?

Graphene has emerged as one of the most promising nanomaterials because of its unique combination of exceptional properties: it is not only the thinnest but also one of the strongest materials; it conducts heat better than all other materials; it is an excellent conductor of electricity; it is optically transparent, yet so dense that it is impermeable to gases – not even helium, the smallest gas atom, can pass through it.

Graphene’s unique combination of extraordinary properties offers a fascinating material platform for the development of next-generation technologies in many areas – wearable and superfast electronics, ultrasensitive sensors, multifunctional composites and coatings, membranes, medicine nd biotechnology, energy harvesting and storage.

石墨烯是目前,最有前途的納米材料之一,因為它結合了獨特的特性:它不僅是最薄的,而且也是最堅固的材料之一; 它比目前所有其他材料的導熱性更好; 是極好的電導體; 它在光學上是透明的,但密度如此之大,以至於氣體不能滲透——即使是最小的氣體原子氦也不能通過它。

石墨烯獨特的非凡性能組合為許多領域的下一代技術的開發提供了一個迷人的材料平台——可穿戴和超高速電子、超靈敏傳感器、多功能複合材料和塗層、膜、醫學和生物技術、能量收集和存儲。

What is Graphene?

Graphene is the name for a single layer (monolayer) sheet of carbon atoms that are bonded together in a repeating pattern of hexagons. This sheet is only one atom thick. Monolayers of graphene stacked on top of each other form graphite. 

In scientific terms: The extraordinary characteristics of graphene originate from the 2p orbitals, which form the π state bands that delocalize over the sheet of carbons that constitute graphene.

Harder than diamond yet more elastic than rubber; tougher than steel yet lighter than aluminum – graphene is the strongest known material.

石墨烯是單層(單層)碳原子片的名稱,這些碳原子以重複的六邊形圖案連接在一起。這張紙只有一個原子厚。堆疊在彼此頂部的單層石墨烯形成石墨。

用科學術語來說:石墨烯的非凡特性源於 2p 軌道,它們形成 π 態帶,在構成石墨烯的碳片上離域。

比鑽石硬,比橡膠更有彈性;比鋼堅韌但比鋁輕——石墨烯是已知最強的材料。

How was graphene discovered?

Before graphene was first demonstrated in 2004 by Andre Geim and Konstantin Novoselov, two physicists from the University of Manchester, (for which they received the Nobel Prize in 2010) scientists argued that strictly 2D crystalline materials were thermodynamically unstable and could not exist.

Graphene had already been studied theoretically in 1947 by P.R. Wallace as a text book example for calculations in solid state physics. He predicted the electronic structure and noted the linear dispersion relation. The wave equation for excitations was written down by J.W. McClure already in 1956, and the similarity to the Dirac equation was discussed by G.W. Semenoff in 1984.

In 2002, Geim became interested in graphene and challenged a PhD student to polish a hunk of graphite to as few layers as possible. He managed to produce a flake of graphite roughly 1,000 layers thick – a little short of the mark.

在 2004 年,曼徹斯特大學的兩位物理學家 Andre Geim 和 Konstantin Novoselov 首次展示石墨烯之前(他們因此獲得了 2010 年諾貝爾獎),科學家們認為嚴格的二維晶體材料在熱力學上是不穩定的,不可能存在。

1947 年,P.R. Wallace 已經對石墨烯進行了理論研究,作為固體物理學計算的教科書示例。 他預測了電子結構並註意到了線性色散關係。 激發的波動方程由 J.W. McClure 早在 1956 年就已經提出,G.W. 1984 年的塞門諾夫。

2002 年,Geim 對石墨烯產生了興趣,並要求一名博士生將一大塊石墨拋光到盡可能少的層數。 他設法生產出大約 1,000 層厚的石墨片——略低於標準。

Graphene uses and applications

Energy storage and solar cells
Graphene-based nanomaterials have many promising applications in energy-related areas. Just some recent examples: Graphene improves both energy capacity and charge rate in rechargeable batteries; activated graphene makes superior supercapacitors for energy storage; graphene electrodes may lead to a promising approach for making solar cells that are inexpensive, lightweight and flexible; and multifunctional graphene mats are promising substrates for catalytic systems.

Researchers also have discovered a critical and unexpected relationship between the graphene’s chemical/structural defectiveness as a host material for electrodes and its ability to suppress the growth of dendrites – branch-like filament deposits on the electrodes that can penetrate the barrier between the two halves of the battery and potentially cause electrical shorts, overheating and fires (“Defect-free graphene might solve lithium-metal batteries’ dendrite problem”).

These examples highlight the four major energy-related areas where graphene will have an impact: solar cells, super capacitors, graphene batteries, and catalysis for fuel cells.

By now, you know it also happens to be the world’s strongest material. With that in mind, it’s only fitting that someone has recently gone and used it in a high-end motorcycle helmet. The Graphene Helmet is the result of an 18-month collaboration between Italian luxury brand Momo design and the Italian Institute of Technology’s Graphene Labs division – the latter is in turn a member of the Graphene Flagship development project.

 

儲能和太陽能電池
基於石墨烯的納米材料在能源相關領域有許多有前景的應用。舉幾個最近的例子:石墨烯提高了可充電電池的能量容量和充電率;活化石墨烯可製造出卓越的儲能超級電容器;石墨烯電極可能為製造廉價、輕便和靈活的太陽能電池提供一種有前景的方法;和多功能石墨烯墊是催化系統的有前途的基材。

研究人員還發現了石墨烯作為電極主體材料的化學/結構缺陷與其抑制枝晶生長的能力之間存在關鍵和意想不到的關係 – 枝狀細絲沉積在電極上,可以穿透兩半之間的屏障電池,並可能導致短路、過熱和火災(“無缺陷石墨烯可能會解決鋰金屬電池的枝晶問題”)。

這些例子突出了石墨烯將產生影響的四個主要能源相關領域:太陽能電池、超級電容器、石墨烯電池和燃料電池催化。

到現在為止,您知道它也恰好是世界上最堅固的材料。 考慮到這一點,最近有人把它用在高端摩托車頭盔上是再合適不過的了。石墨烯頭盔是意大利奢侈品牌 Momodesign 與意大利理工學院石墨烯實驗室部門合作 18 個月的成果——後者又是石墨烯旗艦開發項目的成員。

 

Biomedical uses of graphene

Graphene is only recently finding its way into biomedical applications. Most of the recent work in this area focuses on using graphene as a biosensor, i.e., as a passive medium, which monitors some external stimulus, usually by taking advantage of the fact that graphene’s resistance depends strongly on nearby electric fields and signals (see for instance: “Graphene-DNA biosensor selective, simple to create”). But this is from a fundamental point of view nothing new; silicon wires, diamond films and carbon nanotubes all have been already used for this type of application.

Recent research also points to an opportunity to replacing antibiotics with graphene-based photothermal agents to trap and kill bacteria.In the decades-old quest to build artificial muscles, many materials have been investigated with regard to their suitability for actuator application (actuation is the ability of a material to reversibly change dimensions under the influence of various stimuli). Besides artificial muscles, potential applications include microelectromechanical systems (MEMS), biomimetic micro-and nanorobots, and micro fluidic devices. In experiments, scientists have shown that graphene nanoribbons can provide actuation.

石墨烯最近才進入生物醫學應用。該領域最近的大部分工作都集中在使用石墨烯作為生物傳感器,即作為被動介質,監測一些外部刺激,通常是利用石墨烯的電阻強烈依賴於附近電場和信號的事實(參見例如:“石墨烯-DNA 生物傳感器選擇性,易於創建”)。但這從根本上來說並不是什麼新鮮事。矽線、金剛石薄膜和碳納米管都已用於此類應用。

最近的研究還指出了用基於石墨烯的光熱劑代替抗生素來捕獲和殺死細菌的機會。材料在各種刺激的影響下可逆地改變尺寸的能力)。除了人造肌肉,潛在的應用還包括微機電系統 (MEMS)、仿生微型和納米機器人以及微流體設備。在實驗中,科學家們已經證明石墨烯納米帶可以提供驅動。

Graphene pants for women

Designed for practically any activity that requires pants, this pants come with a 3-layer fabric that isn’t just destruction-proof, it’s stretchable, waterproof, and has the ability to regulate your body’s temperature so you could potentially wear the same pair of pants while rock-climbing in the sun or on a skiing trip to a snow-capped peak. The pants’ fabric as well as its construction together help it juggle its different roles, which three-layer fabric on the pants gives it durability as well as versatility.

For starters, the pants designed to be breathable, allowing you to wear them for hours without working up a sweat. If it’s hot out, the pants ensure you remain cool on the inside, but the minute you wear the pants out in the cold, the fabric helps retain body warmth while being wind-proof, keeping you warm and protected on the inside.

The most standout feature however remains the integration of Graphene into its yarn. Hailed as the strongest material known to man, Graphene helps the pants brave practically any amount of abuse without showing any wear and tear.

 

這款褲子幾乎專為任何需要褲子的活動而設計,採用 3 層面料,不僅防破壞,而且可拉伸、防水,並且能夠調節體溫,因此您可以穿同一雙在陽光下攀岩或到白雪皚皚的山峰滑雪旅行時穿褲子。褲子的面料和結構一起幫助它扮演不同的角色,褲子上的三層面料賦予它耐用性和多功能性。

對於初學者來說,褲子設計為透氣性,讓您可以穿幾個小時而不會出汗。如果外面很熱,褲子可以確保你在裡面保持涼爽,但是當你在寒冷中穿褲子的那一刻,這種面料有助於保持身體溫暖,同時防風,讓你保持溫暖並在裡面得到保護。

然而,最突出的特點仍然是將石墨烯集成到其紗線中。石墨烯被譽為人類已知的最堅固的材料,可以幫助褲子抵禦幾乎任何程度的虐待,而不會出現任何磨損。

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