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Catalytic activity for hydrogen evolution reaction in phosphene nanoribbons: A first-principles study
Published in Binoy K. Saikia, Advances in Applied Chemistry and Industrial Catalysis, 2022
As a clean and renewable energy source, hydrogen has always been regarded as the most promising new energy source in the future. The electrochemical hydrogen evolution reaction (HER) is an efficient and cheap method among the many current hydrogen production technologies. (Lasia 2019) Efficient hydrogen evolution electrode materials should have the characteristics of good electrical conductivity, large specific surface area, low hydrogen evolution overpotential, high electrocatalytic activity, good electrochemical stability, and strong corrosion resistance. (Jin et al. 2018) At present, although some precious metal catalysts (Pt) have excellent catalytic activity for hydrogen production, their scarcity and high cost limit their wide application. (Wang et al. 2012) So scientists have been looking for efficient and low-cost hydrogen evolution electrocatalysts, however, the stability and catalytic activity of these materials are difficult to compare with Pt. Two-dimensional materials have many unique electronic properties, are low in price, and have large specific surface areas, which have gradually attracted people's attention.
Two-Dimensional Photocatalytic Heterojunction Hybrid Nanomaterials for Environmental Applications
Published in A. Pandikumar, K. Jothivenkatachalam, S. Moscow, Heterojunction Photocatalytic Materials, 2022
R. Baby Suneetha, Suguna Perumal, P. Karpagavinayagam, C. Vedhi
Two-dimensional materials can be successfully synthesized by mechanical exfoliation, chemical exfoliation, and chemical vapor deposition (CVD) methods. 2D materials with high crystallinity can be synthesized through mechanical exfoliation method, but this is not scalable; chemical exfoliation methods such as electrochemical exfoliation and solvent-assisted exfoliation produce scalable results, but one cannot obtain 2D materials with precise control of lateral size and thickness, while CVD method can form wafer-scale monolayer 2D materials. The 2D materials thus synthesized by any one of the above methods can then be suitably combined to get 2D heterojunction materials. These 2D materials can then be used to prepare modified working electrodes for electrochemical studies. There are several strategies for constructing 2D heterojunctions and they can be broadly classified into two categories, namely, ex situ methods and in situ methods.
2D Magnetic Systems
Published in Ram K. Gupta, Sanjay R. Mishra, Tuan Anh Nguyen, Fundamentals of Low Dimensional Magnets, 2023
Two-dimensional materials are referred to as a class of layered crystalline solids with a few nanometers of thickness. The single layer of atoms, known as a monolayer, is one atom thick, while a few layers can extend up to a thickness of 20–50 nm but should retain the 2D limit without attaining any 3D bulk properties of the material. Graphene is the first 2D material that was realized in 2004 by peeling off from graphite. Isolation of graphene depicted the possibility to get the atomically stable and thin sheets of crystals which show a variety of excellent properties such as high mobility, high conductivity, and high mechanical strength with long spin diffusion length for spintronics devices compared to the existing materials. The atomic-layer structures and exceptional properties of 2D materials make them potential candidates to be used for a wide variety of applications in optoelectronic devices, sensors, energy storage devices, drug delivery, and DNA sequencing. After this, many novel 2D materials are being realized and studied, like transition metal dichalcogenides (TMDs), MX2 (M = Mo, W, Nb, Ta; X = S, Se, Te), graphitic carbon nitride (g-C3N4), hexagonal boron nitride (h-BN), and 2D oxides including lead, phosphorus, and transition metal oxides, etc. These materials cover a range of properties from metals to semimetals, topological insulators, semiconductors, insulators, and superconductors as well. The doping or heterostructures of these 2D materials with other materials can result in improved and novel properties, achieving high sensitivity as well as high power harvest efficiency.
Interfacial and confined molecular-assembly of poly(3-hexylthiophene) and its application in organic electronic devices
Published in Science and Technology of Advanced Materials, 2022
Junhao Liang, Xing Ouyang, Yan Cao
Two-dimensional materials can be designed to improve the charge-carriers mobilities, mechanical, electronic, and optical properties. Taoet al. found a layered 2D nanocrystals of POSS-P3HT can be applied to the organic thin film transistor. The POSS-P3HT synthesized with click chemistry contains one P3HT molecular chain covalently linked with one POSS molecule [104,105]. The TEM bright-field morphology is displayed in Figure 5(a) and the selected-area electron diffraction experiments corresponding to the crystal in Figure 5(a) are shown in Figure 5(b). The simulated pattern with the [12] zone of the 2D crystal on POSS-P3HT is displayed in Figure 5(c). The 2D POSS-P3HT crystals own a hexagonal unit cell with a = b = 1.606 nm, and c = 1.714 nm with a symmetry group of P6. Based on the electron diffraction and wide-angle X-ray diffraction results of 2D crystals, we established the molecular packing model of 2D crystals(Figures 5(d–f)). The P3HT chains interdigitated between two crystalline layers of POSS [106]. The sandwich 2D crystal structures could be also confirmed by the one layer’s thickness (26.7 nm) measured by atomic force microscopy. It is worth mentioning that the power conversion efficiency of the POSS-P3HT 2D crystal is 40% higher than that of the pristine P3HT mixed with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) (Figures 5(g–i)).
Highly sensitive gold-film surface plasmon resonance (SPR) sensor employing germanium selenide (GeSe) nanosheets
Published in Instrumentation Science & Technology, 2022
Ze-Ying Hao, Yao Liu, Zhou-Hao Zhao, Qi Wang
Coating the sensor surface with a layer of nanomaterials is a common method to increase the sensitivity. Popular materials currently include graphene and other two-dimensional materials (e.g., MoS2, WS2). Many studies have been conducted with these materials and have demonstrated their ability to significantly improve the performance of biosensors.[13,14] Graphene is the thinnest man-made material and possesses a rich Π-conjugated structure that promotes direct biological interactions, as well as high carrier mobility that can significantly improve the sensitivity of sensors.[15–17] Monolayer MoS2 is a two-dimensional (2 D) material that outperforms graphene in terms of strong light absorption, absorption efficiency and broad work function, as well as the direct band gap of 1.8 eV due to quantum confinement effects, which are higher than the indirect band gap of bulk MoS2.[18,19] At the same time, MoS2 provides a high affinity surface to absorb biomolecules by virtue of its hydrophobic properties, making it widely used in recent years for biosensing.[20] Song et al. coated a single layer of MoS2 on the surface of a conventional U-shaped sensor and showed that the sensitivity of the sensor was improved by approximately 70 percent.[14]
Gas detection for NO2 and SO2 based on tape-heme monolayer
Published in Molecular Physics, 2021
Gaofu Guo, Renyi Li, Dong Wei, Zhen Feng, Yaqiang Ma, Yanan Tang, Xianqi Dai
Toxic gases in the environment pose a threat to human health at any moment, for example, hydrogen cyanide (HCN), derived from building fires, binds to cytochrome oxidase to inhibit cell respiration at the cellular level and causes tissue hypoxia secondary to the combination of cyanide and haemoglobin [1,2]. Ammonia (NH3), as an alkaline constituent in the atmosphere [3], burns mucous membranes of skin, eyes and respiratory organs. Sulphur dioxide (SO2) and nitrogen dioxide (NO2), as pollutants, are soluble in water and play an important role in the formation of acid rain [4,5]. In recent years, ultra-thin two-dimensional materials have attracted great interest due to their novel structure, photoelectric, mechanical and thermal properties. However, previous reports have proved that the gas sensing capabilities of 2D materials are very significant. Some gaseous molecules are physically adsorbed on pristine graphene, GaSe, WSe2, MoS2, SnS, SnP3, MoO3, black phosphorene, and stanene monolayers with small adsorption energy and less charge transfer, which suggests they are inefficient as practical gas sensors [6–14]. It is particularly urgent to design miniature, portable, highly sensitive and selective gas sensors to monitor toxic gases in the environment.