We have produced ultrathin epitaxial graphite films which show remarkable 2D electron gas (2DEG) behavior. The films, composed of typically 3 graphene sheets, were grown by thermal decomposition on the (0001) surface of 6H-SiC, and characterized by surface-science techniques. The low-temperature conductance spans a range of localization regimes according to the structural state (square resistance 1.5 kOhm to 225 kOhm at 4 K, with positive magnetoconductance). Low resistance samples show characteristics of weak-localization in two dimensions, from which we estimate elastic and inelastic mean free paths. At low field, the Hall resistance is linear up to 4.5 T, which is well-explained by n-type carriers of density 10^{12} cm^{-2} per graphene sheet. The most highly-ordered sample exhibits Shubnikov - de Haas oscillations which correspond to nonlinearities observed in the Hall resistance, indicating a potential new quantum Hall system. We show that the high-mobility films can be patterned via conventional lithographic techniques, and we demonstrate modulation of the film conductance using a top-gate electrode. These key elements suggest electronic device applications based on nano-patterned epitaxial graphene (NPEG), with the potential for large-scale integration.

Ultrathin epitaxial graphite: 2D electron gas properties and a route toward graphene-based nanoelectronics

Recent advances in photodegradation of antibiotic residues in water

https://iopscience.iop.org/article/10.1149/2.0171912jes/pdf

Review—Recent Developments on Graphene-Based Electrochemical Sensors toward Nitrite

A novel electrochemical sensor based on silver/halloysite nanotube/molybdenum disulfide nanocomposite for efficient nitrite sensing.

The use of mixed-metal single source precursors for the synthesis of complex metal oxides

In the present study, well-defined one-dimensional (1D) rod-like strontium vanadate (SrV2O6) was prepared by simple hydrothermal method without using any other surfactants/templates. The successful formation of rod-like SrV2O6 was confirmed by various analytical and spectroscopic techniques. Interestingly, for the first time the dual role of as-prepared rod-like SrV2O6 were employed as an electrochemical sensor for the detection of caffeic acid (CA) as well as visible light active photocatalyst for the degradation of metronidazole (MNZ) antibiotic drug. As an electrochemical sensor, the SrV2O6 modified glassy carbon electrode (GCE) demonstrated a superior electrocatalytic activity for the detection of CA by chronoamperometry and cyclic voltammetry (CVs). In addition, the electrochemical sensor exhibited a good current response for CA with excellent selectivity, wide linear response range, lower detection limit and sensitivity of 0.01–207 µM, 4 nM and 2.064 μA μM−1cm−2, respectively. On the other hand, as-synthesized rod-like SrV2O6 showed highly efficient and versatile photocatalytic performances for the degradation of MNZ, which degrades above 98% of MNZ solution under visible light irradiation within 60 min. The obtained results evidenced that the improvement of rod-like SrV2O6 might be a resourceful electrocatalyst and photocatalyst material in the probable applications of environmental and biomedical applications.

/pdf/a-selective-electrochemical-sensor-for-caffeic-acid-and-4801dkvqwy.pdf

A selective electrochemical sensor for caffeic acid and photocatalyst for metronidazole drug pollutant - A dual role by rod-like SrV 2 O 6 .

Graphene-based materials receive attention in the field of energy and environmental application. The unique physiochemical assets such as the high surface area, high thermal stability, chemical flexibility, high electron mobility and mechanical solidity make it a highly versatile material for different applications. In this critical review, the application of graphene-based material in energy and environmental remediation is discussed in detail. More specifically, the role of graphene in thought-provoking research fields, viz. solar cell, photocatalytic water splitting, photocatalytic degradation of organic pollutants and heavy metal removal, is focused. As graphene possesses very good carrier mobility, it enhances the photocatalytic performance of semiconducting materials. Very interestingly, graphene is being used in both hole transport layer and electron transport layer in solar cell. Similarly, high surface area of graphene assists in heavy metal removal by adsorption. The challenges and recent achievements in these fields are highlighted in this review.

Emerging energy and environmental application of graphene and their composites: a review

In this present scenario, for the first time, we propose a facile and simple wet chemical approach for the fabrication of two-dimensional (2D) cerium tungstate (CeW2O9;CeW) nanosheets and evaluated as an electrochemical sensor for the detection of nitrite ions. The successful formation of CeW2O9 nanosheets was confirmed by various physicochemical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, Raman, Scanning electron microscope, Transmission electron microscope and Energy dispersive X-ray studies. The electrochemical properties of the CeW nanosheets were studied by using cyclic voltammograms (CV) and chronoamperometric techniques. As an electrochemical sensor, the CeW nanosheets modified glassy carbon electrode (GCE) showed superior electrocatalytic activity in the oxidation of nitrite in terms of higher anodic peak current and lower oxidation potential when compared with unmodified GCE. CeW nanosheets based electrochemical sensor has been fabricated which detect nitrite in wide linear response range, good sensitivity and very low detection limit of 0.02–986 μM, 2.85 μA μM−1 cm−2 and 8 nM, respectively. Moreover, the CeW nanosheets modified GCE exhibited excellent selectivity even in the presence of common metal ions and biologically co-interfering compounds. For the practical viability of the prepared amperometric sensor has been utilized in various water samples such as tap, lake and drinking water and the obtained recoveries are appreciable.

A Novel Cerium Tungstate Nanosheets Modified Electrode for the Effective Electrochemical Detection of Carcinogenic Nitrite Ions

Developing an efficient wastewater treatment technique is one of the major necessities of the twenty-first century, owing to the scarcity of water resources. Besides, it is of paramount important to find appropriate methodologies to economically treat wastewater. Recent advances in nanotechnology have attracted the attention of many researchers for wastewater treatment. The major advantages of such nanomaterial-based systems are that they can be reused and have been found to be very effective. Though many research works have been reported in this regard, there is very limited collective information. Hence, the major objective of this work is to describe recent achievements in nanomaterial-based systems for wastewater treatment. This chapter critically reviews and lists the uses of nanomaterials in wastewater treatment. This comprises the utilization of semiconducting nanoparticles either alone or combined with ozonation, the Fenton process, or sonolysis for effective degradation/removal of organic pollutants. Furthermore, the effectiveness of nanotechnology in antimicrobial activity to produce pure water via an eco-friendly route is discussed. Similarly, the role of nanomaterials in adsorption techniques (specifically, carbon-based nanoadsorbents) to remove heavy metal contamination from industrial wastewater is also discussed in detail.

V. Selvam

Papers

A selective electrochemical sensor for caffeic acid and photocatalyst for metronidazole drug pollutant - A dual role by rod-like SrV 2 O 6 .

Emerging energy and environmental application of graphene and their composites: a review

A Novel Cerium Tungstate Nanosheets Modified Electrode for the Effective Electrochemical Detection of Carcinogenic Nitrite Ions

Recent Advances in Nanomaterials for Wastewater Treatment

Photocatalytic degradation of organic contaminants by g-C3N4/EPDM nanocomposite film: Viable, efficient and facile recoverable.