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Zhong Lin Wang - One of the best experts on this subject based on the ideXlab platform.
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from contact electrification to triboelectric nanogenerators
Reports on Progress in Physics, 2021Co-Authors: Zhong Lin WangAbstract:Although the contact electrification (CE) (or usually called 'triboelectrification') effect has been known for over 2600 years, its scientific mechanism still remains debated after decades. Interest in studying CE has been recently revisited due to the invention of triboelectric nanogenerators (TENGs), which are the most effective approach for converting random, low-frequency mechanical energy (called high entropy energy) into electric power for distributed energy applications. This review is composed of three parts that are coherently linked, ranging from basic physics, through classical electrodynamics, to technological advances and engineering applications. First, the mechanisms of CE are studied for general cases involving solids, liquids and gas phases. Various physics models are presented to explain the fundamentals of CE by illustrating that electron transfer is the dominant mechanism for CE for solid-solid Interfaces. Electron transfer also occurs in the CE at Liquid-Solid and liquid-liquid Interfaces. An electron-cloud overlap model is proposed to explain CE in general. This electron transfer model is extended to Liquid-Solid Interfaces, leading to a revision of the formation mechanism of the electric double layer at Liquid-Solid Interfaces. Second, by adding a time-dependent polarization termPscreated by the CE-induced surface electrostatic charges in the displacement fieldD, we expand Maxwell's equations to include both the medium polarizations due to electric field (P) and mechanical aggitation and medium boundary movement induced polarization term (Ps). From these, the output power, electromagnetic (EM) behaviour and current transport equation for a TENG are systematically derived from first principles. A general solution is presented for the modified Maxwell's equations, and analytical solutions for the output potential are provided for a few cases. The displacement current arising frome∂E/∂t is responsible for EM waves, while the newly added term ∂Ps/∂t is responsible for energy and sensors. This work sets the standard theory for quantifying the performance and EM behaviour of TENGs in general. Finally, we review the applications of TENGs for harvesting all kinds of available mechanical energy that is wasted in our daily life, such as human motion, walking, vibration, mechanical triggering, rotating tires, wind, flowing water and more. A summary is provided about the applications of TENGs in energy science, environmental protection, wearable electronics, self-powered sensors, medical science, robotics and artificial intelligence.
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studying of contact electrification and electron transfer at liquid liquid interface
Nano Energy, 2021Co-Authors: Zhong Lin Wang, Xiuzhong Zhao, Qiwei Zheng, Lin Fang, Li Zheng, Xiangyu ChenAbstract:Abstract Triboelectric nanogenerator (TENG) provides an effective approach for studying transferred charges at solid-solid or Liquid-Solid Interfaces. Here, by dripping a liquid droplet through an immiscible organic solution (transformer oil), we used single-electrode mode TENG to measure the transferred charges on the liquid droplet once it goes down in the solution. The falling droplets (with volume of 25 μL) can generate negative charges on its surface and the output charges amount can reach − 5.3рC by passing through the transformer oil. In addition, we found that both the рH value and the electrostatic shielding effect of free ions greatly hinder the electron transfer efficiency at L-L contact electrification. Combining the experimental results and previous research, we infer that there are both ion transfer and electron transfer happening in the L-L electrification.
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contact electrification at the liquid solid interface
Chemical Reviews, 2021Co-Authors: Shiquan Lin, Zhong Lin Wang, Xiangyu ChenAbstract:Interfaces between a liquid and a solid (L-S) are the most important surface science in chemistry, catalysis, energy, and even biology. Formation of an electric double layer (EDL) at the L-S interface has been attributed due to the adsorption of a layer of ions at the solid surface, which causes the ions in the liquid to redistribute. Although the existence of a layer of charges on a solid surface is always assumed, the origin of the charges is not extensively explored. Recent studies of contact electrification (CE) between a liquid and a solid suggest that electron transfer plays a dominant role at the initial stage for forming the charge layer at the L-S interface. Here, we review the recent works about electron transfer in Liquid-Solid CE, including scenerios such as liquid-insulator, liquid-semiconductor, and liquid-metal. Formation of the EDL is revisited considering the existence of electron transfer at the L-S interface. Furthermore, the triboelectric nanogenerator (TENG) technique based on the Liquid-Solid CE is introduced, which can be used not only for harvesting mechanical energy from a liquid but also as a probe for probing the charge transfer at Liquid-Solid Interfaces.
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understanding contact electrification at liquid solid Interfaces from surface electronic structure
Nature Communications, 2021Co-Authors: Mingzi Sun, Zhong Lin Wang, Bolong HuangAbstract:The charge transfer phenomenon of contact electrification even exists in the liquid–solid interface by a tiny droplet on the solid surface. In this work, we have investigated the contact electrification mechanism at the liquid–solid interface from the electronic structures at the atomic level. The electronic structures display stronger modulations by the outmost shell charge transfer via surface electrostatic charge perturbation than the inter-bonding-orbital charge transfer at the liquid–solid interface, supporting more factors being involved in charge transfer via contact electrification. Meanwhile, we introduce the electrochemical cell model to quantify the charge transfer based on the pinning factor to linearly correlate the charge transfer and the electronic structures. The pinning factor exhibits a more direct visualization of the charge transfer at the liquid–solid interface. This work supplies critical guidance for describing, quantifying, and modulating the contact electrification induced charge transfer systems in triboelectric nanogenerators in future works. Understanding contact electrification within the liquid–solid interface is critical for further applications in energy conversion and storage devices. Here, the authors reveal liquid–solid interactions regarding the charge transfer mechanism and pinning factor from the electronic perspective.
Carlos Vega De Las Heras - One of the best experts on this subject based on the ideXlab platform.
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interfacial free energy and tolman length of curved liquid solid Interfaces from equilibrium studies
The Journal of Physical Chemistry, 2020Co-Authors: Pablo Montero De Hijes, Jorge R Espinosa, Valentino Bianco, Eduardo Sanz Garcia, Carlos Vega De Las HerasAbstract:In this work, we study by means of simulations of hard spheres the equilibrium between a spherical solid cluster and the fluid. In the NVT ensemble we observe stable/metastable clusters of the solid phase in equilibrium with the fluid, representing configurations that are global/local minima of the Helmholtz free energy. Then, we run NpT simulations of the equilibrated system at the average pressure of the NVT run and observe that the clusters are critical because they grow/shrink with a probability of 1/2. Therefore, a crystal cluster equilibrated in the NVT ensemble corresponds to a Gibbs free energy maximum where the nucleus is in unstable equilibrium with the surrounding fluid, in accordance with what has been recently shown for vapor bubbles in equilibrium with the liquid. Then, within the Seeding framework, we use Classical Nucleation Theory to obtain both the interfacial free energy γ and the nucleation rate. The latter is in very good agreement with independent estimates using techniques that do not rely on Classical Nucleation Theory when the mislabeling criterion is used to identify the molecules of the solid cluster. We therefore argue that the radius obtained from the mislabeling criterion provides a good approximation for the radius of tension, R_s . We obtain an estimate of the Tolman length by extrapolating the difference between R e (the Gibbs dividing surface) and R s to infinite radius. We show that such definition of the Tolman length coincides with that obtained by fitting γ versus 1/R_s to a straight line as recently applied to hard spheres.
Gabor A Somorjai - One of the best experts on this subject based on the ideXlab platform.
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Nanodiode-based hot electrons: Influence on surface chemistry and catalytic reactions
CAMBRIDGE UNIV PRESS, 2020Co-Authors: Jeong Young Park, Gabor A SomorjaiAbstract:Understanding fundamental mechanisms for surface electronic excitation is of great importance in surface chemistry. Charge transport through metal-oxide Interfaces plays a significant role in heterogeneous catalysis. Over the last several decades, a number of experimental and theoretical results suggest that this charge flow through metal-support Interfaces leads to catalytic enhancement often observed in mixed catalysts. Direct measurement of charge flow on actual catalysts is a rather challenging task because it requires the use of an electronic circuit. This approach has been enabled by a catalytic nanodiode that is mainly composed of a catalytic metal and semiconducting oxides that form a Schottky contact. In this article, we describe the advances in this approach. We show that there is close connection between the phenomena of hot-electron creation and chemical reaction that occur at both gas-solid and Liquid-Solid Interfaces. The intensity of hot-electron flow is well correlated with the turnover rates of corresponding reactions, which opens the possibility for developing new operando methodologies to monitor catalytic reactions as well as a novel scheme for the electronic control of chemical reactions. © 2020 Materials Research Societ
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an investigation of the influence of chain length on the interfacial ordering of l lysine and l proline and their homopeptides at hydrophobic and hydrophilic Interfaces studied by sum frequency generation and quartz crystal microbalance
Langmuir, 2009Co-Authors: Roger L York, George J Holinga, Gabor A SomorjaiAbstract:Sum frequency generation vibrational spectroscopy (SFG) and quartz crystal microbalance with dissipation monitoring (QCM-D) are employed to study the interfacial structure and adsorbed amount of the amino acids L-lysine and L-proline and their corresponding homopeptides, poly-L-lysine and poly-L-proline, at two Liquid-Solid Interfaces. SFG and QCM-D experiments of these molecules are carried out at the interface between phosphate buffered saline at pH 7.4 (PBS) and the hydrophobic deuterated polystyrene (d8-PS) surface as well as the interface between PBS and hydrophilic fused silica (SiO2). The SFG spectra of the amino acids studied here are qualitatively similar to their corresponding homopeptides; however, the SFG signal from amino acids at the solid/PBS interface is smaller in magnitude relative to their more massive homopeptides at the concentrations studied here. Substantial differences are observed in SFG spectra for each species between the hydrophobic d8-PS and the hydrophilic SiO2 Liquid-Solid Interfaces, suggesting surface-dependent interfacial ordering of the biomolecules. Over the range of concentrations used in this study, QCM-D measurements also indicate that on both surfaces poly-L-lysine adsorbs to a greater extent than its constituent amino acid L-lysine. The opposite trend is demonstrated by poly-L-proline which sticks to both surfaces less extensively than its corresponding amino acid, L-proline. Lastly, we find that the adsorption of the molecules studied here can have a strong influence on interfacial water structure as detected in the SFG spectra.
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an investigation of the influence of chain length on the interfacial ordering of l lysine and l proline and their homopeptides at hydrophobic and hydrophilic Interfaces studied by sum frequency generation and quartz crystal microbalance
Langmuir, 2009Co-Authors: Roger L York, George J Holinga, Gabor A SomorjaiAbstract:Sum frequency generation vibrational spectroscopy (SFG) and quartz crystal microbalance with dissipation monitoring (QCM-D) are employed to study the interfacial structure and adsorbed amount of the amino acids l-lysine and l-proline and their corresponding homopeptides, poly-l-lysine and poly-l-proline, at two liquid−solid Interfaces. SFG and QCM-D experiments of these molecules are carried out at the interface between phosphate buffered saline at pH 7.4 (PBS) and the hydrophobic deuterated polystyrene (d8-PS) surface as well as the interface between PBS and hydrophilic fused silica (SiO2). The SFG spectra of the amino acids studied here are qualitatively similar to their corresponding homopeptides; however, the SFG signal from amino acids at the solid/PBS interface is smaller in magnitude relative to their more massive homopeptides at the concentrations studied here. Substantial differences are observed in SFG spectra for each species between the hydrophobic d8-PS and the hydrophilic SiO2 liquid−solid i...
Qingdao Zeng - One of the best experts on this subject based on the ideXlab platform.
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solvent dependent self assemblies and pyridine modulation of a porphyrin molecule at liquid solid Interfaces
Langmuir, 2020Co-Authors: Jingfei Hou, Ke Deng, Qingdao Zeng, Peng Lei, Ting Meng, Fengying ZhaoAbstract:On the highly oriented pyrolytic graphite (HOPG) surface, a new porphyrin molecule MT-4 containing a porphine core with six alkyl chains and two carboxyl groups has been explored using scanning tun...
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on surface crystallization behaviors of h bond donor acceptor complexes at liquid solid Interfaces
Langmuir, 2019Co-Authors: Linxiu Cheng, Qingdao Zeng, Xunwen Xiao, Beatriz Feringan, Raquel Gimenez, Qiaojun Fang, Teresa Sierra, Chen WangAbstract:Two-dimensional (2D) crystallization behaviors of A-TPC n ( n = 4, 6, 10), T3C4, and hydrogen-bonded complexes T3C4@TPC n ( n = 4, 6, 10) are investigated by means of scanning tunneling microscope (STM) observations and density functional theory (DFT) calculations. The STM observations reveal that A-TPC4, A-TPC10, and T3C4 self-organize into dumbbell-shaped structures, well-ordered bright arrays, and zigzag structures, respectively. Interestingly, T3C4@TPC10 fails to form the cage-ball structure, whereas T3C4@TPC4 and T3C4@TPC6 co-assemble into cage-ball structures with the same lattice parameters. The filling rates of the balls of these two kinds of cage-ball structures depend heavily on the deposition sequence. As a result, the filling rates of the cages in T3C4/A-TPC n ( n = 4, 6) with deposition of T3C4 anterior to A-TPC n are higher than those in A-TPC n/T3C4 ( n = 4, 6) with the opposite deposition sequence. Furthermore, lattice defects formed by T3C4 coexist with the cage-ball structures. Moreover, the similar energy per unit area of lattice defects (-0.101 kcal mol-1 A-2) and the two cage-ball networks (-0.194 and -0.208 kcal mol-1 A-2, respectively), illustrating the similar stabilities of lattice defects and cage-ball networks, demonstrates the rationality of lattice defects. Combining STM investigations and DFT calculations, this work could provide a useful approach to investigate the 2D crystallization mechanisms of supramolecular liquid crystals on surfaces.
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supramolecular self assembly of hexaphenylbenzene derivatives with different symmetry and number of carboxylic acid at liquid solid Interfaces
Journal of Physical Chemistry C, 2016Co-Authors: Lixin Cai, Liancheng Wang, Shizhao Kang, Yanfang Geng, Ke Deng, Qiyu Zheng, Qingdao ZengAbstract:Functional molecules, especially with carboxyl groups are crucial in building supramolecular structures. It is great important to study the effect of the symmetry, number of carboxyl groups on the self-assembly behavior of corresponding molecules. A series of hexaphenylbenzene (HPB) derivatives (HPB-1,3,5-3A, HPB-1,2,4-3A, and HPB-1,4-2A) substituted with different number of carboxyl groups at different position have been synthesized and their self-assembled structures were investigated at both 1-phenyloctane/HOPG and heptanoic acid/HOPG Interfaces by using scanning tunneling microscopy (STM) technique. The self-assembled mechanisms of these HPB-based compounds were further studied with the help of density functional theory (DFT) calculations. The results indicate that symmetry and number of carboxyl groups as well as solvent play a significant role on the tuning self-assemble process resulting in various structures.
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Supramolecular Self-Assembly of Hexaphenylbenzene Derivatives with Different Symmetry and Number of Carboxylic Acid at Liquid/Solid Interfaces
2016Co-Authors: Lixin Cai, Liancheng Wang, Shizhao Kang, Yanfang Geng, Ke Deng, Qiyu Zheng, Qingdao ZengAbstract:Functional molecules, especially with carboxyl groups are crucial in building supramolecular structures. It is great important to study the effect of the symmetry, number of carboxyl groups on the self-assembly behavior of corresponding molecules. A series of hexaphenylbenzene (HPB) derivatives (HPB-1,3,5-3A, HPB-1,2,4-3A, and HPB-1,4-2A) substituted with different number of carboxyl groups at different position have been synthesized and their self-assembled structures were investigated at both 1-phenyloctane/HOPG and heptanoic acid/HOPG Interfaces by using scanning tunneling microscopy (STM) technique. The self-assembled mechanisms of these HPB-based compounds were further studied with the help of density functional theory (DFT) calculations. The results indicate that symmetry and number of carboxyl groups as well as solvent play a significant role on the tuning self-assemble process resulting in various structures
Valentino Bianco - One of the best experts on this subject based on the ideXlab platform.
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interfacial free energy and tolman length of curved liquid solid Interfaces from equilibrium studies
Journal of Physical Chemistry C, 2020Co-Authors: Montero P De Hijes, Jorge R Espinosa, Valentino Bianco, Eduardo Sanz, Carlos VegaAbstract:In this work, we study by means of simulations of hard spheres the equilibrium between a spherical solid cluster and the fluid. In the NVT ensemble we observe stable/metastable clusters of the soli...
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interfacial free energy and tolman length of curved liquid solid Interfaces from equilibrium studies
The Journal of Physical Chemistry, 2020Co-Authors: Pablo Montero De Hijes, Jorge R Espinosa, Valentino Bianco, Eduardo Sanz Garcia, Carlos Vega De Las HerasAbstract:In this work, we study by means of simulations of hard spheres the equilibrium between a spherical solid cluster and the fluid. In the NVT ensemble we observe stable/metastable clusters of the solid phase in equilibrium with the fluid, representing configurations that are global/local minima of the Helmholtz free energy. Then, we run NpT simulations of the equilibrated system at the average pressure of the NVT run and observe that the clusters are critical because they grow/shrink with a probability of 1/2. Therefore, a crystal cluster equilibrated in the NVT ensemble corresponds to a Gibbs free energy maximum where the nucleus is in unstable equilibrium with the surrounding fluid, in accordance with what has been recently shown for vapor bubbles in equilibrium with the liquid. Then, within the Seeding framework, we use Classical Nucleation Theory to obtain both the interfacial free energy γ and the nucleation rate. The latter is in very good agreement with independent estimates using techniques that do not rely on Classical Nucleation Theory when the mislabeling criterion is used to identify the molecules of the solid cluster. We therefore argue that the radius obtained from the mislabeling criterion provides a good approximation for the radius of tension, R_s . We obtain an estimate of the Tolman length by extrapolating the difference between R e (the Gibbs dividing surface) and R s to infinite radius. We show that such definition of the Tolman length coincides with that obtained by fitting γ versus 1/R_s to a straight line as recently applied to hard spheres.