Defect-engineered graphene chemical sensors with ultrahigh sensitivity
25 May 2016-Physical Chemistry Chemical Physics (The Royal Society of Chemistry)-Vol. 18, Iss: 21, pp 14198-14204
TL;DR: This study revealed that defect engineering in graphene has significant potential for fabricating ultra-sensitive graphene chemical sensors and systematically investigated the mechanism of gas sensing, which indicated that the vacancy defect is a major contributing factor to the enhanced sensitivity.
Abstract: We report defect-engineered graphene chemical sensors with ultrahigh sensitivity (e.g., 33% improvement in NO2 sensing and 614% improvement in NH3 sensing). A conventional reactive ion etching system was used to introduce the defects in a controlled manner. The sensitivity of graphene-based chemical sensors increased with increasing defect density until the vacancy-dominant region was reached. In addition, the mechanism of gas sensing was systematically investigated via experiments and density functional theory calculations, which indicated that the vacancy defect is a major contributing factor to the enhanced sensitivity. This study revealed that defect engineering in graphene has significant potential for fabricating ultra-sensitive graphene chemical sensors.
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TL;DR: In this paper, the authors present and discuss recent advances in synthesis strategies of assembled graphene-based superstructures of 1D, 2D, and 3D macroscopic shapes in the forms of fibers, thin films and foams/aerogels.
Abstract: Development of next-generation sensor devices is gaining tremendous attention in both academia and industry because of their broad applications in manufacturing processes, food and environment control, medicine, disease diagnostics, security and defense, aerospace, and so forth. Current challenges include the development of low-cost, ultrahigh, and user-friendly sensors, which have high selectivity, fast response and recovery times, and small dimensions. The critical demands of these new sensors are typically associated with advanced nanoscale sensing materials. Among them, graphene and its derivatives have demonstrated the ideal properties to overcome these challenges and have merged as one of the most popular sensing platforms for diverse applications. A broad range of graphene assemblies with different architectures, morphologies, and scales (from nano-, micro-, to macrosize) have been explored in recent years for designing new high-performing sensing devices. Herein, this study presents and discusses recent advances in synthesis strategies of assembled graphene-based superstructures of 1D, 2D, and 3D macroscopic shapes in the forms of fibers, thin films, and foams/aerogels. The fabricated state-of-the-art applications of these materials in gas and vapor, biomedical, piezoresistive strain and pressure, heavy metal ion, and temperature sensors are also systematically reviewed and discussed, and their sensing performance is compared.
192 citations
TL;DR: In this article, a review of recent achievements of 2D nanostructured materials for chemiresistive-type gas sensors is presented, where the basic sensing mechanism is described based on charge transfer behavior between gas species and 2D nano-materials.
Abstract: Two-dimensional (2D) nanostructures are gaining tremendous interests due to the fascinating physical, chemical, electrical, and optical properties. Recent advances in 2D nanomaterials synthesis have contributed to optimization of various parameters such as physical dimension and chemical structure for specific applications. In particular, development of high performance gas sensors is gaining vast importance for real-time and on-site environmental monitoring by detection of hazardous chemical species. In this review, we comprehensively report recent achievements of 2D nanostructured materials for chemiresistive-type gas sensors. Firstly, the basic sensing mechanism is described based on charge transfer behavior between gas species and 2D nanomaterials. Secondly, diverse synthesis strategies and characteristic gas sensing properties of 2D nanostructures such as graphene, metal oxides, transition metal dichalcogenides (TMDs), metal organic frameworks (MOFs), phosphorus, and MXenes are presented. In addition, recent trends in synthesis of 2D heterostructures by integrating two different types of 2D nanomaterials and their gas sensing properties are discussed. Finally, this review provides perspectives and future research directions for gas sensor technology using various 2D nanomaterials.
177 citations
Cites background from "Defect-engineered graphene chemical..."
...revealed that defect density in graphene can enhance sensitivity up to 33 and 614% toward NO2 and NH3, respectively, as compared to the sensitivities of pristine graphene [52]....
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TL;DR: The detection performances of the graphene-based electrochemical biosensors are in the range of ng/mL and have reached up to fg/mL in detecting the targets of NCDs with higher selectivity, sensitivity and stability with good reproducibility attributes.
162 citations
TL;DR: In this article, the performance of suspended Exfoliated Black Phosphorus (BP)-based chemical sensors was investigated by floating BP flakes on top of electrode posts to provide full (both sides) adsorption sites and avoid interface scattering effects.
Abstract: The studies on enhancing the sensitivities of chemical sensors based on two-dimensional (2D) materials have been focused primarily on surface modifications including defect engineering, chemical doping, and incorporation of metal nanoparticles. Exfoliated black phosphorus (BP), which is one of the 2D materials, has attracted considerable attention because it offers higher sensitivity than other 2D materials (e.g., graphene and MoS2). In this study, for the first time, we attempt to increase the performance of BP chemical sensors to their theoretical limit by floating BP flakes on top of electrode posts in order to provide full (both sides) adsorption sites and avoid interface scattering effects. Our suspended BP gas sensors fabricated via dry transfer showed higher sensing performances than the conventional supported BP gas sensors (gas response was increased by approximately 23% at 200 ppm). In addition, faster response and recovery with high reproducibility were observed in suspended BP chemicals sensors than in the supported ones. Our work reveals the full potential of pristine BP-based chemical sensors and paves the way for the next-generation high performance 2D chemical sensors.
110 citations
TL;DR: The results can prove the tailoring sensing behavior of the gas sensor according to different structures of materials.
Abstract: The microstructures of metal oxide-modified reduced graphene oxide (RGO) are expected to significantly affect room-temperature (RT) gas sensing properties, where the microstructures are dependent on the synthesis methods. Herein, we demonstrate the effect of microstructures on RT NO2 sensing properties by taking typical SnO2 nanoparticles (NPs) embellished RGO (SnO2 NPs-RGO) hybrids as examples. The samples were synthesized by growing SnO2 NPs on RGO through hydrothermal reduction (SnO2 NPs-RGO-PR), which display the advantages such as high reactivity of the SnO2 surface with NO2, more oxygen vacancies (OV) and chemisorbed oxygen (OC), close contact between SnO2 NPs and RGO, and large surface area, compared to the samples prepared by one-pot hydrothermal synthesis from Sn4+ and GO (SnO2 NPs-RGO-IS), and the assembly of SnO2 NPs on RGO (SnO2 NPs-RGO-SA). As expected, the SnO2 NPs-RGO-PR-based sensor presents high sensitivity towards 5 ppm NO2 (65.5%), but 35.0% for the SnO2 NPs-RGO-IS-based sensor and 32.8% for the SnO2 NPs-RGO-SA-based sensor at RT. Meanwhile, the corresponding response time and recovery time calculated by achieving 90% of the current change of the SnO2 NPs-RGO-PR-based sensor for exposure to NO2 is 12 s and to air is 17 s, respectively, whereas 74/42 s for the SnO2 NPs-RGO-IS-based sensor and 77/90 s for the SnO2 NPs-RGO-SA-based sensor. The results can prove the tailoring sensing behavior of the gas sensor according to different structures of materials.
87 citations
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Abstract: Generalized gradient approximations (GGA’s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. [S0031-9007(96)01479-2] PACS numbers: 71.15.Mb, 71.45.Gm Kohn-Sham density functional theory [1,2] is widely used for self-consistent-field electronic structure calculations of the ground-state properties of atoms, molecules, and solids. In this theory, only the exchange-correlation energy EXC › EX 1 EC as a functional of the electron spin densities n"srd and n#srd must be approximated. The most popular functionals have a form appropriate for slowly varying densities: the local spin density (LSD) approximation Z d 3 rn e unif
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TL;DR: An efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set is presented and the application of Pulay's DIIS method to the iterative diagonalization of large matrices will be discussed.
Abstract: We present an efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrices will be discussed. Our approach is stable, reliable, and minimizes the number of order ${\mathit{N}}_{\mathrm{atoms}}^{3}$ operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special ``metric'' and a special ``preconditioning'' optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calculations. It will be shown that the number of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order ${\mathit{N}}_{\mathrm{atoms}}^{2}$ scaling is found for systems containing up to 1000 electrons. If we take into account that the number of k points can be decreased linearly with the system size, the overall scaling can approach ${\mathit{N}}_{\mathrm{atoms}}$. We have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large number of different systems (liquid and amorphous semiconductors, liquid simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable. \textcopyright{} 1996 The American Physical Society.
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TL;DR: In this article, a method for generating sets of special points in the Brillouin zone which provides an efficient means of integrating periodic functions of the wave vector is given, where the integration can be over the entire zone or over specified portions thereof.
Abstract: A method is given for generating sets of special points in the Brillouin zone which provides an efficient means of integrating periodic functions of the wave vector. The integration can be over the entire Brillouin zone or over specified portions thereof. This method also has applications in spectral and density-of-state calculations. The relationships to the Chadi-Cohen and Gilat-Raubenheimer methods are indicated.
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TL;DR: Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena can now be mimicked and tested in table-top experiments.
Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.
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TL;DR: In this paper, the authors present an ab initio quantum-mechanical molecular-dynamics calculations based on the calculation of the electronic ground state and of the Hellmann-Feynman forces in the local density approximation.
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