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Schematic illustration of 3D N-doped graphene electrode incorporated with dopamine [reprinted with permission from ref. 73, Copyright© Elsevier]
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Graphene is one of the astounding recent advancements in current science and one of the most encouraging materials for application in cutting-edge electronic gadgets. Graphene and its derivatives like graphene oxide and reduced graphene oxide have emerged as significant nanomaterials in the area of sensors. Furthermore, doping of graphene and its d...
Citations
... The adsorbed gas molecules can alter the concentration of charge carriers in graphene, thereby affecting its conductivity. There is a hypothesis that such devices may have the capability to detect single molecules [38]. To fully harness the potential of graphene sensors, it is crucial to understand the dynamics between the graphene surface and the adsorbed molecules [39]. ...
In this work, we explore the potential of 2D materials, particularly graphene and its derivatives, for eco-friendly electricity generation and air pollution reduction. Leveraging the significant surface area of graphene nanomaterials, the susceptibility of these graphene-based nanostructures to hazardous substances and their applicability in clean solar cell (SSC) devices were systematically investigated using density functional theory (DFT), as implemented within Gaussian 5.0 code. Time-dependent DFT (TD-DFT) was employed to characterize the UV-visible spectrum of unstrained nanostructures. Herein, we considered three potentially harmful gases—CO, NH3, and Br2. Adsorption calculations revealed a notable interaction between the pure graphene nanostructure and Br2 gas, while the S-doped counterpart exhibited reduced interaction. Saturated S-doped nanostructures demonstrated an enhanced affinity for NH3 and CO gases compared to their pure S-doped counterparts, attributed to the sulfur (S) atom facilitating gas molecule binding to the nanostructure’s surface. Furthermore, simulations of the SSC device architecture indicated the superior performance of the pure graphene nanostructure in terms of light-harvesting efficiency, injection energy, and electron injection into the lower conduction band of CBM titanium dioxide (TiO2). These findings suggest a potential avenue for developing nanostructures tailored for SSC devices and gas sensors, offering a dual solution to address air pollution concerns.
Density function theory was used to compute the ground and excited state properties for pure and sulfur-doped graphene nanostructures. The hybrid function B3LYP with a 6–31G* basis set was utilized to describe the exchange correlation. Gauss Sum 2.2 software is used to estimate the density of state (DOS) for all structures under investigation.
... With B sp 2 hybridised into the lattice of graphene, the planar geometry of graphene remains preserved. Furthermore, N is easily incorporated into graphene structures due to its comparable atomic size to C and the formation of strong bonds with each other [57]. Also, nitrogen doping into the framework of carbon-based materials has been rapidly progressing to acquire advantageous semiconducting characteristics. ...
Heavy metal poisoning has a life-threatening impact on the human body to aquatic ecosystems. This necessitates designing a convenient green methodology for the fabrication of an electrochemical sensor that can detect heavy metal ions efficiently. In this study, boron (B) and nitrogen (N) co-doped laser-induced porous graphene (LIGBN) nanostructured electrodes were fabricated using a direct laser writing technique. The fabricated electrodes were utilised for the individual and simultaneous electrochemical detection of lead (Pb²⁺) and cadmium (Cd²⁺) ions using a square wave voltammetry technique (SWV). The synergistic effect of B and N co-doping results in an improved sensing performance of the electrode with better sensitivity of 0.725 µA/µM for Pb²⁺ and 0.661 µA/µM for Cd²⁺ ions, respectively. Moreover, the sensing electrode shows a low limit of detection of 0.21 µM and 0.25 µM for Pb²⁺ and Cd²⁺ ions, with wide linear ranges from 8.0 to 80 µM for Pb²⁺ and Cd²⁺ ions and high linearity of R² = 0.99 in case of simultaneous detection. This rapid and facile method of fabricating heteroatom-doped porous graphene opens a new avenue in electrochemical sensing studies to detect various hazardous metal ions.
... Nearly two decades ago, one-atom thickness (0.334 nm) twodimensional layer structure composed of six-member ring of sp 2 -hybridized carbon atoms [1,2] named graphene has been discovered. But till now graphene and its derivatives are showing its extensive applications in scientific world such as supercapacitor [3], power storage [4], sensor [5], adsorbent [6], catalyst carrier [7] and dye degradation [8]. These numerous applications exist due to its unique properties such as high theoretical surface area [9], high intrinsic mobility [10], strong mechanical strength [11], high chemical stability [12], zero band gap [13] and thermal conductivity [14]. ...
The environment is adversely affected by toxic synthetic dye effluent from multiple sectors. As a result of these dyes’ harmful effects on living things, the aquatic system needs to be eliminated of them. In this study, we have synthesized reduced graphene oxide (RGO) using the aqueous extract of ripe Tamarindus Indica fruit and leaf by an environmentally acceptable green approach. The synthesized material is capable of eliminating harmful dyes from the aqueous medium by adsorption phenomenon, and it is shown that an about 77% to 97% different types of dye removal occur by both RGO samples. The formation of RGO was verified using powder X-ray diffraction (XRD) analysis, Fourier-transform infrared spectroscopy (FTIR), and UV–Vis spectroscopy. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) exhibited that the morphology of RGO is sheet-like structure. Adsorption isotherm models for Freundlich and Langmuir, and additionally adsorption kinetics for pseudo-first and pseudo-second order, have been analyzed for three dyes on synthesized RGO adsorbents: methyl green (MG), crystal violet (CV), and Congo red (CR). Adsorption isotherm analysis reveals that the adsorption of MG dye fits best in the Langmuir model, while the adsorption of CV and CR dyes best fits in the Freundlich model. Kinetics analysis also explores that the adsorption of all dyes follows pseudo-second-order kinetics. To gain insight into the characteristics of the adsorption environment, a thermodynamic analysis of adsorption was conducted as well and it was shown that the dye adsorption phenomenon is endothermic and spontaneous. Up to five cycles, the adsorption capacity of RGO was tested, and it showed that there was no discernible decline in adsorption capacity.
... Doped nitrogen results in electrocatalytic activity improvement of the metal nanoparticles by providing the necessary electron withdrawal 42 . Also, placing nitrogen in graphenebased materials increases the charge carriers and the interaction between the support and metal nanoparticles, which leads to the important role of nitrogen in electrochemical sensors [43][44][45][46] . That is, the higher electronegativity of nitrogen compared to carbon, not only does not reduce the electrical conductivity and stability of the carbon support but also provides the necessary electron withdraw to increase the activity of metal nanoparticles. ...
To precise screening concentration of ascorbic acid (AA), a novel electrochemical sensor was prepared using palladium nanoparticles decorated on nitrogen-doped graphene quantum dot modified glassy carbon electrode (PdNPs@N-GQD/GCE). For this purpose, nitrogen doped GQD nanoparticles (N-GQD) were synthesized from a citric acid condensation reaction in the presence of ethylenediamine and subsequently modified by palladium nanoparticles (PdNPs). The electrochemical behavior of AA was investigated, in which the oxidation peak appeared at 0 V related to the AA oxidation. Considering the synergistic effect of Pd nanoparticles as an active electrocatalyst, and N-GQD as an electron transfer accelerator and electrocatalytic activity improving agent, PdNPs@N-GQD hybrid materials showed excellent activity in the direct oxidation of AA. In the optimal conditions, the voltammetric response was linear in the range from 30 to 700 nM and the detection limit was calculated to be 23 nM. The validity and the efficiency of the proposed sensor were successfully tested and confirmed by measuring AA in real samples of chewing tablets, and fruit juice.
... However, the sensitivity, detection limit, and response/recovery time of such versatile materials have scope of further improvement. One of the approaches to achieve this, is to tune their electronic properties and surface dynamics via either functionalization, doping, or chemical modification [24]. Nitrogen with its proximity to carbon in the periodic table is a potentially appropriate candidate for such heteroatom doping. ...
... The further improvement in the ambient sensing response in N-rGO/ZnO over other materials can be attributed to the catalytic nature of the substituted nitrogen dopants that act as electron donors and increase the charge carrier density of the material. The electronegativity of nitrogen is 3.04 while that of carbon is 2.55 [24]. Due to this, nitrogen causes charge separation by producing a net polarization in the carbon network. ...
... Pyridinic-N acts as a center for catalytic reactions that give rise to defect sites and active sites in the carbon lattice [26,38]. These active sites created by the doped N atoms favor the adsorption and subsequent activation of analyte gas molecules by stimulating the charge transfer between the analyte molecule and the active site [24]. Pyridinic-N also possesses a lone pair of electrons and therefore has greater electronegativity than carbon. ...
The present investigations demonstrate for the first time, fast and reversible ammonia (NH3) gas sensing performance of nitrogen-doped reduced graphene oxide/zinc oxide (N-rGO/ZnO) nanocomposites at room temperature. The motivation to use nitrogen as a dopant stems from the fact that it lies next to carbon in the periodic table, therefore is similar in size and covalent nature. The synthesis of N-rGO/ZnO was carried out by a simple two-step in situ method via the wet chemical route. The NH3 sensing potential of reduced graphene oxide (rGO), nitrogen-doped rGO (N-rGO), and rGO–ZnO nanocomposites synthesized by similar routes was also assessed. N-rGO/ZnO was found to exhibit superior NH3 sensing performance as compared to rGO, N-rGO, and rGO–ZnO. Further, the study of the sensing mechanism also affirms that the improved response in N-rGO/ZnO is attributed to the formation of p–n heterojunction sites and the charge activation due to N-dopant. To study the effect of N-doping levels on the NH3 sensing performance of N-rGO/ZnO, different samples were prepared by altering the amount of nitrogen source ammonia solution (0.05, 0.1, 0.2, 0.3 µL mg⁻¹ of GO) in the reaction. Consequently, ZnO nanoparticles of different morphologies anchored to flexible N-rGO sheets were obtained. The nitrogen doping has been quantified using X-ray photoelectron spectroscopy analysis. An optimal gas sensing performance of 18.35% toward 10-ppm NH3 with response/recovery time 2.5/72 s was obtained for the 0.1-µL mg⁻¹ sample. The variation in NH3 sensing response in the presence of different %RH levels of humidity was also assessed. The response changed only by 2.6% when %RH is changed from 10 to 80%. The sensor also displayed appreciable stability with ambient aging.
... Furthermore, compared to pristine graphene, the presence of hydroxylated functional groups in GQDs enhances their hydrophilicity and offers extensive possibilities for surface functionalization [39]. Surface functionalization with organic molecules and doping with elements such as sulfur (S), nitrogen (N), phosphorus (P), boron (B), silicon (Si), and magnesium (Mg) significantly enhances the optical characteristics, electronic properties, and chemical reactivity of GQDs, allowing for the fine-tuning of their inherent properties for specific gas-sensing applications [40][41][42]. These exceptional characteristics have accelerated a rapid progress in the development of functionalized GQDs and GQD-based nanocomposites, especially within a wide range of sensing applications. ...
Gas-sensing technology has witnessed significant advancements that have been driven by the emergence of graphene quantum dots (GQDs) and their tailored nanocomposites. This comprehensive review surveys the recent progress made in the construction methods and applications of functionalized GQDs and GQD-based nanocomposites for gas sensing. The gas-sensing mechanisms, based on the Fermi-level control and charge carrier depletion layer theory, are briefly explained through the formation of heterojunctions and the adsorption/desorption principle. Furthermore, this review explores the enhancements achieved through the incorporation of GQDs into nanocomposites with diverse matrices, including polymers, metal oxides, and 2D materials. We also provide an overview of the key progress in various hazardous gas sensing applications using functionalized GQDs and GQD-based nanocomposites, focusing on key detection parameters such as sensitivity, selectivity, stability, response and recovery time, repeatability, and limit of detection (LOD). According to the most recent data, the normally reported values for the LOD of various toxic gases using GQD-based sensors are in the range of 1–10 ppm. Remarkably, some GQD-based sensors exhibit extremely low detection limits, such as N-GQDs/SnO2 (0.01 ppb for formaldehyde) and GQD@SnO2 (0.10 ppb for NO2). This review provides an up-to-date perspective on the evolving landscape of functionalized GQDs and their nanocomposites as pivotal components in the development of advanced gas sensors.
... For this reason, co-doping GO with heteroatoms (N, B, S, P, etc.) is an excellent way to rectify its intrinsic properties while retaining their active sites [15]. This process can offer several advantages, including high electrical conductivity, tunable band-gap engineering, and improved optical properties [15][16][17][18][19]. Co-doping GO with nitrogen (N) and boron (B) can remove a significant oxygen-functional groups, making GO comparable to rGO properties. ...
In this work, we report a low cost and straightforward chemical synthesis of nickel oxide nanoparticles decorated with low amount of nitrogen and boron co-doped reduced GO for a high-performance UV photodetector. For the first time, NiO/NB-rGO nanomaterial was synthesized following the co-precipitation method and subsequently annealed at 400 °C. The nanomaterial was characterized with several techniques such as SEM, TEM, XRD, and Raman spectroscopy. In addition, the device was subjected to electrical characterizations to determine their responsivity, detectivity, and temporal responses both in the absence of illumination (dark conditions) and under UV illumination of 375 nm. In particular, the studied I-V curve was performed to evaluate the coexistence of positive and negative photoconductivity in our device. The results revealed a better photoresponse of NiO/NB-rGO device to UV light, which showed high responsivity (800 A/W), large detectivity (9.4 ×1011 Jones), and fast rise/fall time (1.38/2.17 s) at reverse bias. Consequently, the Schottky contact of NiO/NB-rGO allowed to switch between carriers’ conduction, which displayed both positive and negative photoconductance at reverse and forward bias.
... Likewise, when Cl atom is introduced (as depicted in Fig. 2(c)), C-Cl bond distance in Cl@CO 2 H-GQDs has been computed to be 1.76 Å. Our computed bond lengths between C-Cl and C-Br align with previously reported findings [55,56]. Variation in bond lengths between Cl, F, and C can be explained by atomic radii of these them. ...
... [15] By refluxing the heteroatom-doped (N-doped) graphene with a halogen precursor, a heteroatom-halogen doped and functionalized graphene nanostructure can be obtained, as well as theoretically doped and functionalized heteroatom-halogen carbon nanomaterials with high chemical and environmental stability. [16] ...
Due to their low cost, accessibility of resources, and improved stability and durability, carbon‐based nanomaterials have attracted significant attention as cathode materials for oxygen reduction reactions. These materials also exhibit intrinsic physical and electrochemical features. However, their potential for use in fuel cells is constrained by low ORR activity and slow kinetics. Carbon nanomaterials can be functionalized and doped with heteroatoms to change their morphologies and generate a large number of oxygen reduction active sites to lessen the problems. Doping the carbon lattice with heteroatoms like N, S, and P and functionalizing the carbon structure with −OCH 3 , −F, −COO ⁻ , −O ⁻ are two of these modifications that can change specific properties of the carbon nanomaterials like expanding interlayer distance, producing a large number of active sites, and enhancing oxygen reduction activity. When compared to pristine carbon‐based nanomaterials, these doped and functionalized carbon nanomaterials, including their composites, exhibit accelerated rate performance, outstanding stability, and higher methanol tolerance. This article summarizes the most recent developments in heteroatom‐doped and functionalized carbon‐based nanomaterials, covering different synthesis approaches, characterization methods, electrochemical performance, and oxygen reduction reaction mechanisms. As cathode materials for fuel cell technologies, the significance of heteroatom co‐doping and transition metal heteroatom co‐doping is also underlined.
... The heteroatom-doping and introduction of functional groups in GNSs have been studied in the literature for some time [33][34][35][36][37][38][39][40][41][42]. Yadav et al. reviewed the synthesis and characterization of N-doped Graphene [43]. ...
The continuous production of high-quality, few-layer graphene nanosheets (GNSs) functionalized with nitrogen-containing groups was achieved via a two-stage reaction method. The initial stage produces few-layer GNSs by utilizing our recently developed glycine-bisulfate ionic complex-assisted electrochemical exfoliation of graphite. The second stage, developed here, uses a radical initiator and nitrogen precursor (azobisisobutyronitrile) under microwave conditions in an aqueous solution for the efficient nitrogen functionalization of the initially formed GNSs. These nitrile radical reactions have great advantages in green chemistry and soft processing. Raman spectra confirm the insertion of nitrogen functional groups into nitrogen-functionalized graphene (N-FG), whose disorder is higher than that of GNSs. X-ray photoelectron spectra confirm the insertion of edge/surface nitrogen functional groups. The insertion of nitrogen functional groups is further confirmed by the enhanced dispersibility of N-FG in dimethyl formamide, ethylene glycol, acetonitrile, and water. Indeed, after the synthesis of N-FG in solution, it is possible to disperse N-FG in these liquid dispersants just by a simple washing–centrifugation separation–dispersion sequence. Therefore, without any drying, milling, and redispersion into liquid again, we can produce N-FG ink with only solution processing. Thus, the present work demonstrates the ‘continuous solution processing’ of N-FG inks without complicated post-processing conditions. Furthermore, the formation mechanism of N-FG is presented.
