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17 pages, 6207 KiB

Open AccessArticle

Carbon Nanofibers Synthesized at Different Pressures for Detection of NO₂ at Room Temperature

by Nikita I. Lapekin, Pavel B. Kurmashov, Tatyana V. Larina, Yurii A. Chesalov, Dmitry S. Kurdyumov, Arina V. Ukhina, Evgene A. Maksimovskiy, Arcady V. Ishchenko, Vitalii I. Sysoev and Alexander G. Bannov

Chemosensors 2023, 11(7), 381; https://doi.org/10.3390/chemosensors11070381 - 7 Jul 2023

Cited by 2 | Viewed by 1269

Abstract

In this paper, room-temperature chemiresistive gas sensors for NO₂ detection based on CVD-grown carbon nanofibers (CNFs) were investigated. Transmission electron microscopy, low-temperature nitrogen adsorption, and X-ray diffraction were used to investigate the carbon nanomaterials. CNFs were synthesized in a wide range of [...] Read more.

In this paper, room-temperature chemiresistive gas sensors for NO₂ detection based on CVD-grown carbon nanofibers (CNFs) were investigated. Transmission electron microscopy, low-temperature nitrogen adsorption, and X-ray diffraction were used to investigate the carbon nanomaterials. CNFs were synthesized in a wide range of pressure (1–5 bar) by CO_x-free decomposition of methane over the Ni/Al₂O₃ catalyst. It was found that the increase in pressure during the synthesis of CNFs induced the later deactivation of the catalyst, and the yield of CNFs decreased when increasing pressure. Sensing properties were determined in a dynamic flow-through installation at NO₂ concentrations ranging from 1 to 400 ppm. Ammonia detection was tested for comparison in a range of 100–500 ppm. The obtained sensors based on CNFs synthesized at 1 bar showed high responses of 1.7%, 5.0%, and 10.0% to 1 ppm, 5 ppm, and 10 ppm NO₂ at 25 ± 2 °C, respectively. It was shown that the obtained non-modified carbon nanomaterials can be used successfully used for room temperature detection of nitrogen dioxide. It was found that the increase in relative humidity (RH) of air induced growth of response, and this effect was facilitated after reaching RH ~35% for CNFs synthesized at elevated pressures. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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14 pages, 4673 KiB

Open AccessArticle

The Influence of Carboxyl-Functionalized Carbon Dots on Ethanol Selectivity in Gas Sensing

by Futong Tian, Guoxing Ma, Xing Zhao, Jie Gao, Jingwen Zhang, Hui Suo and Chun Zhao

Chemosensors 2023, 11(7), 370; https://doi.org/10.3390/chemosensors11070370 - 2 Jul 2023

Cited by 2 | Viewed by 1394

Abstract

For semiconductor tin dioxide (SnO₂) materials, the oxygen adsorption theory often struggles to explain their selectivity towards specific gases. Therefore, it is worth considering altering the surface functional groups of SnO₂ to modify its surface state and enhance its selectivity [...] Read more.

For semiconductor tin dioxide (SnO₂) materials, the oxygen adsorption theory often struggles to explain their selectivity towards specific gases. Therefore, it is worth considering altering the surface functional groups of SnO₂ to modify its surface state and enhance its selectivity towards specific gases. Due to the rich functional groups on the surfaces of carbon dots, this study employed a hydrothermal method to prepare three types of carbon dots with varying carboxyl functional group contents by adjusting the hydrothermal time. These carbon dots were then used as dopants and combined with SnO₂ to create composite gas-sensitive devices. The gas-sensing test results indicate that the introduction of carboxyl functional groups can enhance the selectivity of SnO₂ towards ethanol. Furthermore, at any operating temperature within the range of 150–300 °C, the higher the carboxyl functional group content on the surface of carbon dot-doped SnO₂, the higher the sensitivity towards ethanol. By employing density functional theory (DFT), the interaction energies between the surfaces of carbon dots and surface carboxyl groups with the target gas were calculated. These calculations validated the gas-sensing test results, confirming that the presence of carboxyl functional groups enhances the selectivity towards ethanol. The results of this study can provide new insights into the research on the selective mechanism of gas-sensitive materials. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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20 pages, 4647 KiB

Open AccessEditor’s ChoiceArticle

Flexible Miniaturized Electrochemical Sensors Based on Multiwalled Carbon Nanotube-Chitosan Nanomaterial for Determination of Nitrite in Soil Solutions

by Ana-Maria Gurban, Lucian-Gabriel Zamfir, Petru Epure, Ioana-Raluca Șuică-Bunghez, Raluca Mădălina Senin, Maria-Luiza Jecu, Maria Lorena Jinga and Mihaela Doni

Chemosensors 2023, 11(4), 224; https://doi.org/10.3390/chemosensors11040224 - 5 Apr 2023

Cited by 14 | Viewed by 2437

Abstract

Flexible screen-printed electrodes (SPE) were modified in a simple manner with different composite nanomaterials based on carbon allotropes, polymers, and metallic nanoparticles, for amperometric detection of nitrites in soil. Multiwalled carbon nanotubes (MWCNT), chitosan (CS), silver nanoparticles (AgNPs), 1,8-diaminonaphthalene (1,8-DAN), and a sol-gel [...] Read more.

Flexible screen-printed electrodes (SPE) were modified in a simple manner with different composite nanomaterials based on carbon allotropes, polymers, and metallic nanoparticles, for amperometric detection of nitrites in soil. Multiwalled carbon nanotubes (MWCNT), chitosan (CS), silver nanoparticles (AgNPs), 1,8-diaminonaphthalene (1,8-DAN), and a sol-gel (SG) matrix were used for modification of the carbon paste working electrodes. Sensitive and selective detection of nitrite was achieved by using a MWCNT-CS-modified sensor, in acetate buffer at pH 5, at an applied potential of 0.58 V vs. Ag/AgCl. The MWCNT-CS-based sensor displayed a specific sensitivity of 204.4 mA·M⁻¹·cm⁻², with a detection limit of 2.3 µM (S/N = 3) in a linear range up to 1.7 mM, showing good stability, reproducibility, and selectivity towards other interfering species. A miniaturized portable system using the developed flexible electrochemical MWCNT-CS-based sensors was dedicated for the detection of nitrite in different samples of soil solutions extracted by using suction lysimeters. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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14 pages, 36554 KiB

Open AccessArticle

Graphene Nanogap Interdigitated Asymmetric Electrodes for Photodetection

by Rabiaa Elkarous, Afrah Bardaoui, Jérôme Borme, Nabil Sghaier, Pedro Alpuim, Diogo M. F. Santos and Radhouane Chtourou

Chemosensors 2023, 11(3), 181; https://doi.org/10.3390/chemosensors11030181 - 8 Mar 2023

Cited by 3 | Viewed by 2562

Abstract

This work proposes a high-performance asymmetric gold/graphene/platinum photodetector. The new photodetector, operating without bias, integrates interdigitated 100 nm spaced metallic contacts that induce a built-in potential and a short carrier path, allowing an improvement in the separation and collection of the photocarriers. A [...] Read more.

This work proposes a high-performance asymmetric gold/graphene/platinum photodetector. The new photodetector, operating without bias, integrates interdigitated 100 nm spaced metallic contacts that induce a built-in potential and a short carrier path, allowing an improvement in the separation and collection of the photocarriers. A chemical vapor deposition graphene layer is transferred onto the interdigitated electrodes elaborated using high-resolution electron-beam lithography. Three devices with different side dimensions (100, 1000, and 3000 µm) are fabricated, and their photoresponsivities are evaluated at different wavelengths. The 100 µm device shows the highest photoresponsivity of 358 A/W at a 400 nm illumination. These promising results confirm the proposed design’s ability to increase the photodetector’s active area, improve light absorption, and achieve high separation and collection of photogenerated carriers. This makes it of great interest for optoelectronic applications. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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17 pages, 3722 KiB

Open AccessArticle

Methylene Blue-Modified Biochar from Sugarcane for the Simultaneous Electrochemical Detection of Four DNA Bases

by Qusai Hassan, Zhixin Meng, Meissam Noroozifar and Kagan Kerman

Chemosensors 2023, 11(3), 169; https://doi.org/10.3390/chemosensors11030169 - 1 Mar 2023

Cited by 2 | Viewed by 1791

Abstract

The abnormal levels of four DNA bases, namely guanine (G), adenine (A), thymine (T), and cytosine (C) are implicated in several cancers, metabolic diseases, and HIV/AIDS. Therefore, the accurate detection and concentration measurement of these four DNA bases is of significant interest. Furthermore, [...] Read more.

The abnormal levels of four DNA bases, namely guanine (G), adenine (A), thymine (T), and cytosine (C) are implicated in several cancers, metabolic diseases, and HIV/AIDS. Therefore, the accurate detection and concentration measurement of these four DNA bases is of significant interest. Furthermore, there has recently been a push towards developing chemical sensors which are more sustainable and cost-effective. Herein, we developed a graphite paste electrode which incorporated the biochar of sugarcane and methylene blue (GPE-SC-MB) in order to simultaneously detect these four DNA bases. The linear ranges obtained for the four DNA bases are 0.67–38.67 µM for G, 0.67–126.67 µM for A, and 6.67–1600 µM for T and C. The limit-of-detection (LOD) values obtained were 0.037 μM for G, 0.042 µM for A, 4.25 μM for T, and 5.33 µM for C. The electroactive surface area of the electrode as well as the diffusion coefficients for each analyte were determined. Lastly, the GPE-SC-MB was tested in real samples using human saliva with recovery values between 99.0 and 103.0%. Thus, biochar from sugarcane proved to be an effective electrode modifier material for the development of sensitive electrochemical sensors. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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17 pages, 4026 KiB

Open AccessArticle

The Platinization of Graphite Composites Turns Widespread and Low-Cost Materials into Hydrogen Peroxide Sensors and High-Value Biosensor Transducers

by Myriam Caval, Carla Sanna, Salvatore Marceddu, Gaia Rocchitta and Pier Andrea Serra

Chemosensors 2023, 11(3), 153; https://doi.org/10.3390/chemosensors11030153 - 21 Feb 2023

Cited by 1 | Viewed by 2024

Abstract

Electrochemical microsensors and biosensors have been widely used in many fields, in particular neurochemical monitoring, because of their features. Usually, hydrogen peroxide (HP), obtained as a by-product of an enzymatic reaction, is the detected compound on transducers made of precious metals, in particular [...] Read more.

Electrochemical microsensors and biosensors have been widely used in many fields, in particular neurochemical monitoring, because of their features. Usually, hydrogen peroxide (HP), obtained as a by-product of an enzymatic reaction, is the detected compound on transducers made of precious metals, in particular platinum. The over-time increase in the price of platinum and its alloys requires the use of miniaturizable low-cost supports that can be suitably modified with the deposition of Pt particles; among them, graphite is the most widespread. In the present paper, carbon-composition resistors (CCRs) and pencil leads (PLs) of different diameters (0.3, 0.5 and 2.0 mm), mainly made up of graphite, clay and some other components were used as carbonaceous support for the deposition of platinum. Platinizations were carried out by means of cyclic voltammetry (CV) and constant potential amperometry (CPA) techniques. On the platinized supports, hydrogen peroxide (HP) and ascorbic acid (AA) sensitivity were assessed in order to verify the possibility of using them as transducers of amperometric biosensors. All the used protocols determined the occurrence of HP monitoring, not appreciable on carbonaceous surfaces. We chose 0.3 mm Ø PLs for the construction of glucose biosensors by appropriately modifying the platinum surface layering, a permselective polymer, an enzyme booster, the glucose oxidase (GOx) enzyme and a containing network. The biosensor constructed in this way demonstrated a behavior comparable to that obtained using classic platinum wires. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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25 pages, 4063 KiB

Open AccessArticle

Facile Electrodeposition-Based Chemosensors Using PANI and C-Hybrid Nanomaterials for the Selective Detection of Ammonia and Nitrogen Dioxide at Room Temperature

by Alexandru Grigoroiu, Carmen-Marinela Mihailescu, Mihaela Savin, Carmen Aura Moldovan, Costin Brasoveanu, Silviu Dinulescu, Nikolay Djourelov, Georgescu Vlad Cristian, Oana Brincoveanu, Gabriel Craciun, Cristina Pachiu, Ion Stan, Bogdan Firtat, George Stelian Muscalu, Marian Ion and Adrian Anghelescu

Chemosensors 2023, 11(2), 132; https://doi.org/10.3390/chemosensors11020132 - 13 Feb 2023

Cited by 5 | Viewed by 2187

Abstract

Sensor systems for monitoring indoor air quality are vital for the precise quantification of the mechanisms which lead to the deterioration of human health, with a typical person spending an average of 20 h a day in an enclosed space. Thus, a series [...] Read more.

Sensor systems for monitoring indoor air quality are vital for the precise quantification of the mechanisms which lead to the deterioration of human health, with a typical person spending an average of 20 h a day in an enclosed space. Thus, a series of layered chemoresistive sensors, obtained by the facile electrodeposition of carbon nanomaterial-enhanced PANI composites, have been tested for the selective detection of two core indoor pollutants: ammonia and nitrogen dioxide. The sensors were tested with respect to sensitivity and selectivity to the target gasses, with performance being assessed based on response linearity and repeatability at room temperature. Of the tested sensors, two have been identified as having an adequate performance on ammonia, with sensitivities of up to 96.99% and resolutions of up to 0.85 ppm being observed, while on nitrogen dioxide, despite the successful sensor having a lower sensitivity, 10.71%, it has shown high resolution, 1.25 ppm, and linearity over a large concentration domain. These high performances highlight the viability of multi-layers chemosensors based on the electrodeposition of nanomaterial-enhanced conductive polymers for the detection of pollutant gasses, with finetuning of the detection layer allowing the accurate monitoring of a wide range of gasses. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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12 pages, 3032 KiB

Open AccessArticle

Capacitive Humidity Sensor with a Rapid Response Time on a GO-Doped P(VDF-TrFE)/LiCl Composite for Noncontact Sensing Applications

by Enkhzaya Ganbold, Parshant Kumar Sharma, Eun-Seong Kim, Do-Nam Lee and Nam-Young Kim

Chemosensors 2023, 11(2), 122; https://doi.org/10.3390/chemosensors11020122 - 7 Feb 2023

Cited by 7 | Viewed by 2813

Abstract

Humidity-sensing devices are widely utilized in various fields, including the environment, industries, food processing, agriculture, and medical processes. In the past few years, the development of noncontact sensors based on moisture detection has increased rapidly due to the COVID-19 pandemic. Moisture-detection, noncontact and [...] Read more.

Humidity-sensing devices are widely utilized in various fields, including the environment, industries, food processing, agriculture, and medical processes. In the past few years, the development of noncontact sensors based on moisture detection has increased rapidly due to the COVID-19 pandemic. Moisture-detection, noncontact and breath-monitoring sensors have promising applications in various fields. In this study, we proposed a rapid-response graphene oxide (GO)-doped P(VDF-TrFE)/LiCl nanocomposite-based moisture sensor fabricated on an interdigitated electrode. The synthesis of GO/P(VDF-TrFE)/LiCl resulted in a porous structure with nano-sized holes due to the effect of LiCl. Moreover, doped GO improved the conductivity of the sensing film. The created nanoporous structure improved the recovery time better than the response time, with the times being 4.8 s and 7.8 s, respectively. Not only did our sensor exhibit rapid response and recovery times, it also exhibited a high sensitivity of 1708.8 pF/%RH at 25% to 93%RH. We also presented a real-time breath-monitoring system for noncontact sensing applications based on GO-doped P(VDF-TrFE)/LiCl composites. The results revealed that GO-doped P(VDF-TrFE)/LiCl is a good candidate for fabricating real-time moisture-detection noncontact sensing devices. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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12 pages, 2739 KiB

Open AccessArticle

Incorporating Cerium Vanadate into Multi-Walled Carbon Nanotubes for Fabrication of Sensitive Electrochemical Sensors toward Sulfamethazine Determination in Water Samples

by Jingying Ma, Chaoyan Zhang, Xiaoping Hong and Jiyang Liu

Chemosensors 2023, 11(1), 64; https://doi.org/10.3390/chemosensors11010064 - 13 Jan 2023

Cited by 9 | Viewed by 2211

Abstract

We developed a simple hydrothermal technique for the fabrication of a flexible integrated composite containing cerium vanadate (CeVO₄) and multi-walled carbon nanotubes (MWCNTs). The CeVO₄/MWCNTs composite possessed good conductivity and interesting electrochemical catalytic performance when immobilized on a glassy [...] Read more.

We developed a simple hydrothermal technique for the fabrication of a flexible integrated composite containing cerium vanadate (CeVO₄) and multi-walled carbon nanotubes (MWCNTs). The CeVO₄/MWCNTs composite possessed good conductivity and interesting electrochemical catalytic performance when immobilized on a glassy carbon electrode (GCE). This CeVO₄/MWCNTs-GCE sensor provided excellent analytical performance for the detection of the sulfonamide antibacterial drug sulfamethazine (SMZ). Benefiting from the significantly enlarged surface area of the modified electrode and the catalytic effect of CeVO₄-MWCNTs, the sensor offered high sensitivity, good stability, fine selectivity, and a remarkable limit of detection (LOD) of 0.02 μM. Furthermore, the sensor also exhibited ideal performance with good recovery and precision when applied to SMZ residue detection in real aquaculture water samples. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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13 pages, 2671 KiB

Open AccessArticle

Phthalocyanine-Carbon Nanotube Hybrid Materials: Mechanism of Sensor Response to Ammonia from Quantum-Chemical Point of View

by Pavel Krasnov, Victoria Ivanova, Darya Klyamer, Aleksandr Fedorov and Tamara Basova

Chemosensors 2022, 10(11), 479; https://doi.org/10.3390/chemosensors10110479 - 14 Nov 2022

Cited by 3 | Viewed by 2141

Abstract

Quantum chemical calculations of the geometric and electronic structure of periodic hybrid compounds representing carbon nanotubes (10,0) with zinc phthalocyanine molecules ZnPc-xpy (x = 0, 1, 2, 4) on their surface and their interaction with ammonia were carried out to explain [...] Read more.

Quantum chemical calculations of the geometric and electronic structure of periodic hybrid compounds representing carbon nanotubes (10,0) with zinc phthalocyanine molecules ZnPc-xpy (x = 0, 1, 2, 4) on their surface and their interaction with ammonia were carried out to explain the dependence of the sensor response of the hybrid materials to ammonia on the number of substituents in the ZnPc-xpy macrocycle and to clarify the nature of the interaction between ammonia and phthalocyanine molecules. It was found that the key feature of these materials, which determines their sensor response toward ammonia, is the presence of an impurity band in the band gap of a carbon nanotube, formed by the orbitals of macrocycle atoms. When ammonia adsorbs through the formation of hydrogen bonds with the side atoms of phthalocyanine, the energy of this impurity band decreases. As a consequence, the electron population of the conduction band and, accordingly, the electrical conductivity of the hybrid materials become lower. Moreover, with an increase in the number of oxypyrene substituents in ZnPc-xpy, the interaction energy of ammonia increases and, as a result, the decrease in the energy of the impurity band becomes higher. These facts may explain recent experimental measurements of the parameters of the sensor response of similar hybrid materials to ammonia, where, in particular, it was shown that the sensor response is reversible, and its value increases with an increase in the number of oxypyrene substituents in the phthalocyanine macrocycle. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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22 pages, 3781 KiB

Open AccessArticle

Gold-Platinum Core-Shell Nanoparticles with Thiolated Polyaniline and Multi-Walled Carbon Nanotubes for the Simultaneous Voltammetric Determination of Six Drug Molecules

by Shaopei Li, Jiayun Zhou, Meissam Noroozifar and Kagan Kerman

Chemosensors 2021, 9(2), 24; https://doi.org/10.3390/chemosensors9020024 - 28 Jan 2021

Cited by 21 | Viewed by 3995

Abstract

In this proof-of-concept study, a novel nanocomposite of the thiolated polyaniline (tPANI), multi-walled carbon nanotubes (MWCNTs) and gold–platinum core-shell nanoparticles (Au@Pt) (tPANI-Au@Pt-MWCNT) was synthesized and utilized to modify a glassy carbon electrode (GCE) for simultaneous voltammetric determination of six over-the-counter (OTC) drug molecules: [...] Read more.

In this proof-of-concept study, a novel nanocomposite of the thiolated polyaniline (tPANI), multi-walled carbon nanotubes (MWCNTs) and gold–platinum core-shell nanoparticles (Au@Pt) (tPANI-Au@Pt-MWCNT) was synthesized and utilized to modify a glassy carbon electrode (GCE) for simultaneous voltammetric determination of six over-the-counter (OTC) drug molecules: ascorbic acid (AA), levodopa (LD), acetaminophen (AC), diclofenac (DI), acetylsalicylic acid (AS) and caffeine (CA). The nanocomposite (tPANI-Au@Pt-MWCNT) was characterized with transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Using the sensor (GCE-tPANI-Au@Pt-MWCNT) in connection with differential pulse voltammetry (DPV), the calibration plots were determined to be linear up to 570.0, 60.0, 60.0, 115.0, 375.0 and 520.0 µM with limit of detection (LOD) of 1.5, 0.25, 0.15, 0.2, 2.0, and 5.0 µM for AA, LD, AC, DI, AS and CA, respectively. The nanocomposite-modified sensor was successfully used for the determination of these redox-active compounds in commercially available OTC products such as energy drinks, cream and tablets with good recovery yields ranging from 95.48 ± 0.53 to 104.1 ± 1.63%. We envisage that the electrochemical sensor provides a promising platform for future applications towards the detection of redox-active drug molecules in pharmaceutical quality control studies and forensic investigations. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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19 pages, 8734 KiB

Open AccessArticle

Hierarchical Porous Carbon Cobalt Nanocomposites-Based Sensor for Fructose

by Hassan H. Hammud, Nusaybah Alotaibi, Nasreen Al Otaibi, Abdullah Aljaafari, Faheem Ahmed, Ameer Azam and Thirumurugan Prakasam

Chemosensors 2021, 9(1), 6; https://doi.org/10.3390/chemosensors9010006 - 30 Dec 2020

Cited by 9 | Viewed by 3269

Abstract

3D hierarchical graphitic carbon nanowalls encapsulating cobalt nanoparticles HPC-Co were prepared in high yield from solid-state pyrolysis of cobalt 2,2′-bipyridine chloride complex. Annealing of HPC-Co in air gave HPC-CoO, which consists of a mixture of crystallite Co₃O₄ nanospheres and nanorods [...] Read more.

3D hierarchical graphitic carbon nanowalls encapsulating cobalt nanoparticles HPC-Co were prepared in high yield from solid-state pyrolysis of cobalt 2,2′-bipyridine chloride complex. Annealing of HPC-Co in air gave HPC-CoO, which consists of a mixture of crystallite Co₃O₄ nanospheres and nanorods bursting out of mesoporous carbon. Both nanocomposites were fully characterized using SEM, TEM, BET, and powder X-ray diffraction. The elemental composition of both nanocomposites examined using SEM elemental mapping and TEM elemental mapping supports the successful doping of nitrogen. The powder X-ray diffraction studies supported the formation of hexagonal cobalt in HPC-Co, and cubic crystalline Co₃O₄ with cubic cobalt in HPC-CoO. HPC-Co and HPC-CoO can be used as a modified carbon electrode in cyclic voltammetry experiments for the detection of fructose with limit of detection LOD 0.5 mM. However, the single-frequency impedimetric method has a wider dynamic range of 8.0–53.0 mM and a sensitivity of 24.87 Ω mM⁻¹ for the electrode modified with HPC-Co and 8.0–87.6 mM and a sensitivity of 1.988 Ω mM⁻¹ for the electrode modified with HPC-CoO. The LOD values are 3 and 4 mM, respectively. The effect of interference increases in the following order: ascorbic acid, ethanol, urea, and glucose. A simple method was used with negligible interference from glucose to measure the percentage of fructose in a corn syrup sample with an HPC-CoO electrode. A specific capacitance of 47.0 F/g with 76.6% retentivity was achieved for HPC-Co and 28.2 F/g with 87.9% for HPC-CoO for 3000 charge–discharge cycles. Thus, (1) has better sensitivity and specific capacitance than (2), because (1) has a higher surface area and less agglomerated cobalt nanoparticles than (2). Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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Review

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24 pages, 11289 KiB

Open AccessReview

N-Doped Graphene and Its Derivatives as Resistive Gas Sensors: An Overview

by Ali Mirzaei, Somalapura Prakasha Bharath, Jin-Young Kim, Krishna K. Pawar, Hyoun Woo Kim and Sang Sub Kim

Chemosensors 2023, 11(6), 334; https://doi.org/10.3390/chemosensors11060334 - 5 Jun 2023

Cited by 10 | Viewed by 2442

Abstract

Today, resistance gas sensors which are mainly realized from metal oxides are among the most used sensing devices. However, generally, their sensing temperature is high and other materials with a lower operating temperature can be an alternative to them. Graphene and its derivatives [...] Read more.

Today, resistance gas sensors which are mainly realized from metal oxides are among the most used sensing devices. However, generally, their sensing temperature is high and other materials with a lower operating temperature can be an alternative to them. Graphene and its derivatives with a 2D structure are among the most encouraging materials for gas-sensing purposes, because a 2D lattice with high surface area can maximize the interaction between the surface and gas, and a small variation in the carrier concentration of graphene can cause a notable modulation of electrical conductivity in graphene. However, they show weak sensing performance in pristine form. Hence, doping, and in particular N doping, can be one of the most promising strategies to enhance the gas-sensing features of graphene-based sensors. Herein, we discuss the gas-sensing properties of N-doped graphene and its derivatives. N doping can induce a band gap inside of graphene, generate defects, and enhance the conductivity of graphene, all factors which are beneficial for sensing studies. Additionally, not only is experimental research reviewed in this review paper, but theoretical works about N-doped graphene are also discussed. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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26 pages, 1573 KiB

Open AccessReview

Carbon Materials for Organophosphate Pesticide Sensing

by Tamara Lazarević-Pašti

Chemosensors 2023, 11(2), 93; https://doi.org/10.3390/chemosensors11020093 - 27 Jan 2023

Cited by 5 | Viewed by 2793

Abstract

Organophosphates are mainly used as pesticides to protect crops from pests. Because organophosphate pesticides’ use has expanded dramatically worldwide, accurate monitoring of their concentrations in the environment and food has become of utmost importance. Once considered acutely toxic due to acetylcholinesterase inhibition, nowadays [...] Read more.

Organophosphates are mainly used as pesticides to protect crops from pests. Because organophosphate pesticides’ use has expanded dramatically worldwide, accurate monitoring of their concentrations in the environment and food has become of utmost importance. Once considered acutely toxic due to acetylcholinesterase inhibition, nowadays organophosphates are classified as extremely dangerous compounds, with a broad spectrum of toxicity types, by the World Health Organization. Having in mind their extensive use and diverse harmful effects, it is necessary to develop easy, rapid, and highly sensitive methods for organophosphate detection. Regardless of numerous conventional techniques for organophosphate detection, the construction of portable sensors is required to make routine analysis possible. Extensive literature on the different sensors for organophosphate detection is available. Many of them rely on the use of various carbon materials. There are many classes of carbon materials used in sensing element construction, as well as supporting materials. This review focuses on electrochemical and optical sensors based on carbon materials. Special attention is paid to the selectivity, sensitivity, stability, and reusability of reviewed sensors. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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27 pages, 3490 KiB

Open AccessReview

Water Quality Carbon Nanotube-Based Sensors Technological Barriers and Late Research Trends: A Bibliometric Analysis

by Ana-Maria Nasture, Eusebiu Ilarian Ionete, Florin Alexandru Lungu, Stefan Ionut Spiridon and Laurentiu Gabriel Patularu

Chemosensors 2022, 10(5), 161; https://doi.org/10.3390/chemosensors10050161 - 27 Apr 2022

Cited by 7 | Viewed by 3698

Abstract

Water is the key element that defines and individualizes our planet. Relative to body weight, water represents 70% or more for the majority of all species on Earth. Taking care of water as a whole is equivalent with taking care of the entire [...] Read more.

Water is the key element that defines and individualizes our planet. Relative to body weight, water represents 70% or more for the majority of all species on Earth. Taking care of water as a whole is equivalent with taking care of the entire biodiversity or the whole of humanity itself. Water quality is becoming an increasingly important component of terrestrial life, hence intensive work is being conducted to develop sensors for detecting contaminants and assessing water quality and characteristics. Our bibliometric analysis is focused on water quality sensors based on carbon nanotubes and highlights the most important objectives and achievements of researchers in recent years. Due to important measurement characteristics such as sensitivity and selectivity, or low detection limit and linearity, up to the ability to measure water properties, including detection of heavy metal content or the presence of persistent organic compounds, carbon nanotube (CNT) sensors, taking advantage of available nanotechnologies, are becoming increasingly attractive. The conducted bibliometric analysis creates a visual, more efficient keystones mapping. CNT sensors can be integrated into an inexpensive real-time monitoring data acquisition system as an alternative for classical expensive and time-consuming offline water quality monitoring. The conducted bibliometric analysis reveals all connections and maps all the results in this water quality CNT sensors research field and gives a perspective on the approached methods on this specific type of sensor. Finally, challenges related to integration of other trends that have been used and proven to be valuable in the field of other sensor types and capable to contribute to the development (and outlook) for future new configurations that will undoubtedly emerge are presented. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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