The colloidal nanocrystal deposition process: an advanced method to prepare high performance hematite photoanodes for water splitting

2014 ◽  
Vol 7 (7) ◽  
pp. 2250-2254 ◽  
Author(s):  
Ricardo H. Gonçalves ◽  
Edson R. Leite

The association of colloidal deposition of magnetorheological fluid in the presence of an external magnetic field with a sintering process facilitates the attainment of hematite photoanodes with high performance for water splitting.

2017 ◽  
Vol 52 (11) ◽  
pp. 1505-1517
Author(s):  
Arsalan Tayefeh ◽  
Mark Wiesner ◽  
Seyyed A Mousavi ◽  
Reza Poursalehi

The magnetic response of a polyamide nanocomposite membrane under applying a magnetic field has been modeled to evaluate elastic deformation order of magnitude. A PA-Fe3O4 nanocomposite membrane is considered to be modeled under influence of volume plane stress caused by a magnetic field. The modeling of the mechanical behavior of Fe3O4-PA nanocomposite membrane suggests that nanoparticle displacements within the nanocomposite, in the order of 200 nm under applying an external magnetic field, are greater than free volumes or porosities of the polyamide membrane. The membrane can be excited to mechanically vibrate by applying an alternating magnetic field lower than 0.1 T. As the results showed, there is an optimum nanoparticle size, %vol. loading and magnetic field strength to optimize such very small mechanical elastic deformations in the polymer, for controlling membrane functions. The perturbation and decreasing thickness of boundary layer and flow regime can be created by such vibrational elastic deformations on the membrane. It shows that the nanoparticle size has a more significant effect on membrane in-plane movement than their %vol. loading in the polyamide matrix. Decreasing loading of magnetic nanoparticles is very critical to fabricating high-performance membranes with appropriate and controllable magnetic and mechanical properties simultaneously. This phenomenon in vibrational mode might be exploited as a pathway to develop near surface mixing on the membrane, to hydrodynamically lower boundary layer thickness, control membrane separation behavior and enhance cleaning of the membranes, with inducing alternative magnetic fields.


2012 ◽  
Vol 605-607 ◽  
pp. 1356-1359
Author(s):  
Yong Qing Wan ◽  
Ji Jun Fan ◽  
Nan Hui Yu

The internal structure of magnetorheological fluid could change under external magnetic field, as well as its dielectric constant and magnetic conductance. A theoretical model of electromagnetic wave propagation in MRF was established and the basic formula of transmissivity was deduced. Theoretical simulation shows that the electromagnetic wave transmissivity decreases with the increasing of dielectric constant of magnetorheological fluid, and increases with the magnetic permeability. Theoretical analysis indicates that the change of its structure and dielectric magnetic properties of MR fluids is the main cause for the fact that the transmittance could be adjusted under external magnetic field.


2013 ◽  
Vol 6 (4) ◽  
pp. 541-545
Author(s):  
Andrius Klevinskis ◽  
Vytautas Bučinskas ◽  
Lukas Daujotas

The article provides an overview of smart magnetic materials, including the essential properties of smart magnetic liquid materials and discusses the main operating modes of these materials. Theoretical calculations have disclosed changes in the behavior of the magnetorheological fluid determined under the influence of an external magnetic field of the microactuator. Finally, the paper presents the results and conclusions of the conduced experiments. Santrauka Darbe apžvelgtos išmaniosios magnetinės medžiagos, pateiktos pagrindinės išmaniųjų magnetinių skysčių charakteristikos, aptarti pagrindiniai šių medžiagų darbo režimai. Teoriniais skaičiavimais nustatyta mikropavaroje veikiančio magnetoreologinio skysčio savybių kitimo priklausomybė nuo išorinio magnetinio lauko. Darbe pateikti tyrimo metu gautų rezultatų grafikai ir išvados.


RSC Advances ◽  
2020 ◽  
Vol 10 (47) ◽  
pp. 28324-28331 ◽  
Author(s):  
Xiaoyun Liu ◽  
Qian Li ◽  
Yanli Qin ◽  
Yueqiu Jiang

Heterogeneity can be used as a promising method to improve the electrochemical performance of electrode materials; thus, ZnCo2O4@PPy samples were prepared using a facile hydrothermal route and an electrochemical deposition process.


2021 ◽  
Vol 8 ◽  
Author(s):  
Jianfeng Chen ◽  
Qiumeng Qin ◽  
Chaoqun Peng ◽  
Wenyao Liang ◽  
Zhi-Yuan Li

We present a hybrid gyromagnetic photonic crystal (GPC) waveguide composed of different GPC waveguide segments possessing various cylinder radii and waveguide widths but biased by a uniform external magnetic field. We demonstrate in frequency and time domains that based on the strong coupling of two counter-propagating topologically protected one-way edge states, the intriguing slow light rainbow trapping (SLRT) of electromagnetic (EM) waves can be achieved, that is, EM waves of different frequencies can be slowed down and trapped at different positions without cross talk and overlap. More importantly, due to the existence of one-way edge states, external EM waves can be non-reciprocally coupled to the SLRT waveguide channel, although the incident position of the EM wave is far away from the waveguide channel. Besides, the frequency range of the slow light states can also be easily regulated by tuning the intensity of an external magnetic field, which is very beneficial to solve the contradiction between slow light and broad bandwidth. Our results can be applied to the design of high-performance photonic devices, such as an optical buffer, optical switch, and optical filter.


2013 ◽  
Vol 873 ◽  
pp. 436-440
Author(s):  
Bao Zhong Han ◽  
Wei Zhou ◽  
Chang Lin Liu ◽  
Dan Liu ◽  
Xiang Wang

Magnetic phenomenon is one of the most fundamental phenomena of substances. All substances possess strong or weak magnetic property, and have different responds to external magnetic field. Development of high performance materials by using external magnetic field is an important research field of material science. In this study, a static magnetic field is applied during thermoforming processing of low density polyethylene (LDPE)/carbon nanotube (CNT), LDPE/nanographite composites. The effect of magnetic field treatment on dielectric property of these composites is investigated. Experimental results indicate that CNT and nanographite orientate in melted LDPE under the magnetic field. The electrical conductance, the dielectric constant and the dielectric loss angular tangent value of LDPE/CNT and LDPE/ nanographite composites along the magnetic field direction all increase.


2021 ◽  
Vol 7 (2) ◽  
pp. 19
Author(s):  
Aldo Girimonte ◽  
Andrea Stefani ◽  
Massimo Innocenti ◽  
Claudio Fontanesi ◽  
Roberto Giovanardi

This study focuses on the influence of an applied external magnetic field on the electrodeposition process and capacitive performances of MnO2, as pseudo-capacitive active material for supercapacitors electrodes. MnO2 was electrochemically deposited on Si/Au substrates in the presence and in the absence of a 0.5 T magnet, and its capacitive performance was tested via electrochemical characterization. The samples obtained in the presence of the magnetic field show a positive influence on the deposition process: the increase in deposition efficiency leads to more compact and uniform MnO2 coatings, with a decrease in capacitance values for the samples produced with the magnetic field.


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