Quantifying the triboelectric series Zou, Haiyang; Zhang, Ying; Guo, Litong ...
Nature communications,
03/2019, Volume:
10, Issue:
1
Journal Article
Peer reviewed
Open access
Triboelectrification is a well-known phenomenon that commonly occurs in nature and in our lives at any time and any place. Although each and every material exhibits triboelectrification, its ...quantification has not been standardized. A triboelectric series has been qualitatively ranked with regards to triboelectric polarization. Here, we introduce a universal standard method to quantify the triboelectric series for a wide range of polymers, establishing quantitative triboelectrification as a fundamental materials property. By measuring the tested materials with a liquid metal in an environment under well-defined conditions, the proposed method standardizes the experimental set up for uniformly quantifying the surface triboelectrification of general materials. The normalized triboelectric charge density is derived to reveal the intrinsic character of polymers for gaining or losing electrons. This quantitative triboelectric series may serve as a textbook standard for implementing the application of triboelectrification for energy harvesting and self-powered sensing.
Contact-electrification is a universal effect for all existing materials, but it still lacks a quantitative materials database to systematically understand its scientific mechanisms. Using an ...established measurement method, this study quantifies the triboelectric charge densities of nearly 30 inorganic nonmetallic materials. From the matrix of their triboelectric charge densities and band structures, it is found that the triboelectric output is strongly related to the work functions of the materials. Our study verifies that contact-electrification is an electronic quantum transition effect under ambient conditions. The basic driving force for contact-electrification is that electrons seek to fill the lowest available states once two materials are forced to reach atomically close distance so that electron transitions are possible through strongly overlapping electron wave functions. We hope that the quantified series could serve as a textbook standard and a fundamental database for scientific research, practical manufacturing, and engineering.
In this paper, α-Fe
2
O
3
was prepared by hydrothermal and chemical precipitation methods, respectively, and its gas sensing properties toward CH
4
were systematically studied. The larger specific ...surface area of the materials provided them potential and considerable gas adsorption abilities. The results of gas-sensing measurements indicated the synthesized α-Fe
2
O
3
materials presented a p-type conductive nature. The sensitivities of the devices based on the different material fabrication methods were measured to be 195% and 214%, respectively, at 370°C for the concentration of 2000 ppm CH
4
. In addition, the sensing mechanism was discussed and simulated by first-principles calculation. The results revealed the higher surface adsorption energy of α-Fe
2
O
3
, which verified the experimental conclusions of our work. Our research suggests that α-Fe
2
O
3
is a promising candidate for CH
4
gas sensing in many fields such as mining safety and environmental monitoring.
In this study, an E-fenton oxidation system based on Co-N co-doped carbon nanotubes (Co-N-CNTs) was designed. The Co-N-CNTs system showed fast degradation efficiency and reusability for the ...degradation of rhodamine B (RhB). The XRD and SEM results showed that the Co-N co-doped carbon nanotubes with diameters ranging from 40 to 400 nm were successfully prepared. The E-Fenton degradation performance of Co-N-CNTs was investigated via CV, LSV and AC impedance spectroscopy. The yield of H2O2 could reach 80 mg/L/h within 60 min, and the optimal voltage and preparation temperature for H2O2 yield in this system was −0.7 V (vs. SCE) and 800 °C. For the target pollutant of RhB, the fast removal of RhB was obtained via the Co-N-CNTS/E-Fenton system (about 91% RhB degradation occurred during 60 min), and the •OH played a major role in the RhB degradation. When the Fe2+ concentrations increased from 0.3 to 0.4 mM, the RhB degradation efficiency decreased from 91% to about 87%. The valence state of Co in the Co-N-C catalyst drove a Co2+/Co3+ cycle, which ensured the catalyst had good E-Fenton degradation efficiency. This work provides new insight into the mechanism of an E-Fenton system with carbon-based catalysts for the efficient degradation of RhB.
The rollover of road vehicles is one of the most serious problems related to transportation safety. In this article, a novel rollover prevention control system composed of rollover warning and ...integrated chassis control algorithm is proposed. First, a conventional time-to-rollover warning algorithm was presented based on the 3-degree of freedom vehicle model. In order to improve the precision of vehicle rollover prediction, a back-propagation neural network was adopted to regulate time to rollover online by considering multi-state parameters of the vehicle. Second, a rollover prevention algorithm based on integrated chassis control was investigated, where the active front steering and the active yaw moment control were coordinated by model predictive control methodology. Finally, the algorithms were evaluated under several typical maneuvers utilizing MATLAB/Simulink and Carsim co-simulation. The results show that the proposed neural network time-to-rollover metrics can be a good measure of the danger of rollover, and the roll stability of the simulated vehicle is improved significantly with reduced side slip angle and yaw rate by the proposed integrated chassis control rollover prevention system.
Bioglass coatings derived from electrophoretic deposition method were fused on Ti surface by laser cladding process using a continuous CO2 laser. The specimens were studied by field-emission scanning ...electron microscopy, X-ray diffraction and bonding tests. Titanium oxide layer with hierarchical structures consisting of submicron rows of leaf-like embossments and nano-pores was obtained by combining acid etching and anodization processes, which increased the surface roughness of Ti. When heat-treatment temperature was 700 °C and high, CaSiO3 phase began to crystallize from the bioglass matrix and the crystallinity reached its maximum at 700 °C. During the electrophoretic deposition process, porous bioglass coatings composed of bioglass particles and fibers were deposited on Ti surface. Bioglass coatings with similar hierarchical structure containing submillimeter bioglass beads and microfibers were synthesized on Ti surface by laser fusion. There are no obvious microcracks at the interface of the Ti-coating, which revealed the good bonding between Ti-porcelain. With the laser scanning distance decreased, the bond strength increased accordingly. After only one day immersion in SBF, calcium phosphate began to precipitate on the bioglass coatings' surfaces. The thickness of the calcium phosphate precipitation and the amount of microparticles increased with immersion time.
•Bioglass coatings were fused on Ti surface by laser cladding process.•Surface roughness of Ti was increased by surface modification of Ti.•Apatite precipitated on the bioglass coatings after 1 day immersion.•The thickness of the apatite precipitation increased with immersion time.
•Ti surface was modified by anodic oxidation and ultraviolet irradiation.•Surface modification improved the biological properties of Ti.•The mechanisms of surface modification on biological ...properties of Ti was studied.
Anodic oxidation was applied to produce a homogeneous and uniform array of nanotubes of about 70nm on the titanium (Ti) surface, and then, the nanotubes were irradiated by ultraviolet. The bioactivity of the Ti surface was evaluated by simulated body fluid soaking test. The biocompatibility was investigated by in vitro cell culture test. The results showed that bone-like apatite was formed on the anodic oxidized and UV irradiated Ti surface, but not on the as-polished Ti surface after immersion in simulated body fluid for two weeks. Cells cultured on the anodic oxidized Ti surface showed enhanced cell adhesion and proliferation, also presented an up-regulated gene expression of osteogenic markers OPG, compared to those cultured on the as-polished Ti surface. After UV irradiation, the cell behaviors were further improved, indicating better biocompatibility of Ti surface. Based on these results, it can be concluded that anodic oxidation improved the biological properties (bioactivity and biocompatibility) of Ti surface, while UV irradiation improved the biocompatibility to a better extent. The improved biological properties were attributed to the nanostructures as well as the enhanced hydrophilicity. Therefore, anodic oxidation combined with UV irradiation can be used to enhance the biological properties of Ti-based implants.
Microwave hydrothermal method was used to synthesize BaTiO3 powders. XRD, SEM and EDS were used to characterize the obtained BaTiO3 powder. The obtained BaTiO3 powder is monosized distribution ...equi-axed particles of size 150 nm. The BaTiO3 powder of Ba/Ti ratio close to 1 can be obtained at ratio 1.6 of Ba/Ti in precursor in 2.0 M NaOH solution. The results showed that with the increase the reaction time, the grain size of BaTiO3 powder increases. There is an optimal reaction temperature 80 °C, at which the best crystallization is attained.
Investigations of surface modifications on cast titanium surfaces and titanium-ceramic adhesion were performed. Cast pure titanium was subjected to surface modification by preoxidation and ...introduction of an intermediate layer of SnO
x
by sol–gel process. Surfaces only sandblasted with alumina were used as controls. Specimen surfaces were characterized by XRD and SEM/EDS. The adhesion between the titanium and porcelain was evaluated by three-point flexure bond test. Failure of the titanium–porcelain with preoxidation treatment predominantly occurred at the titanium-oxide interface. Preoxidation treatment did not affect the fracture mode of the titanium–ceramic system and did not increase the bonding strength of Ti–porcelain. However, a thin and coherent SnO
x
film with small spherical pores obtained at 300 °C served as an effective oxygen diffusion barrier and improved titanium–ceramic adhesion. The SnO
x
film changed the fracture mode of the titanium–ceramic system and improved the mechanical and chemical bonding between porcelain and titanium, resulting in the increased bonding strength of titanium–porcelain.
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