Plasma‐Based Synthesis of Freestanding Graphene from a Natural Resource for Sensing Application

Abstract

The bottomup approach, that is, modified Hummers' method, is a well-established chemical synthesis technique to synthesize graphene. However, this technique, not only utilizes strong acids and oxidants [4,5] but also entails numerous steps of synthesis such as dilution, mixing, oxidation, reduction, washing, centrifuging, and intense stirring. [6] On the other hand, some of the bottom-up methods, in particular, chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PE-CVD) are expensive and laborious methodologies comprising pre-synthesis and post-synthesis requirements, that is, high vacuum, pre-heating, and subsequent transfer of graphene to other substrates. [7][8][9] Recently, a new bottom-up approach, so-called atmospheric pressure microwave plasma (APMP) is gaining popularity as it synthesizes graphene without the hassles of pre-heating, high vacuuming, and the need for a substrate. Most importantly, the graphene obtained through this method happens to be freestanding and scalable. [10,11] The precursors used for producing graphene have a significant role in determining the sustainability of the synthesis process. Often graphene is produced from commercially available graphite, [12] graphene oxide (GO), [13] methane, or other unreplenishable hydrocarbons. [14] These resources Atmospheric pressure microwave plasma has the lead in synthesizing freestanding and scalable graphene within seconds without the need for high vacuum and temperature. However, the process is limited in utilizing chemical sources for synthesis, such as methane and ethanol. Herein, the usage of an extract of a sustainable precursor, that is, Melaleuca alternifolia, commonly known as tea tree, is for the first time reported to synthesize graphene nanosheets in atmospheric pressure microwave plasma. The synthesis is carried out in a single step at a remarkably low microwave power of 200 W. The morphology, structure, and electrochemical properties of graphene are studied using state-of-the-art characterization techniques such as Raman spectroscopy, X-ray diffraction, transmission electron microscopy (TEM) and electrochemical impedance spectroscopy. The TEM images reveal the presence of a combination of nanostructures such as nano-horns, nano-rods, or nano-onions consisting of multi-layer graphitic architectures. An excellent sensing capability of as-synthesized graphene is demonstrated through the detection of diuron herbicide. A commendable linear range of 20 µm to 1 mm and a limit of detection of 5 µm of diuron is recorded.

Electrochemiluminescence aptasensor toward femtomolar detection of alpha synuclein oligomer as parkinson's disease marker using CdTe@ZnS quantum dots as luminescent label and graphdiyne@polyaniline as novel co‐reactant

“…Doping of carbon materials with nitrogen (NÀ ) may have more than one precursor or require several steps to synthesize, which are very costly. Recently, Jacob et al demonstrated the Single-step and single-precursor synthesis of N-doped graphene oxide (N-GO) by aniline as the source of carbon and nitrogen at ambient conditions [32]. Herein, we synthesized nitrogen-containing carbon nanolayers modified graphdiyne nanostructure as new co-reactant for development of ECL platform.…”