Browsing by Subject "Janus"

Now showing 1 - 2 of 2

Open Access
The Janus GePas monolayer for efficient photocatalytic water splitting
(2021-08) Özbey, Doğukan Hazar
The sun is considered an inexhaustible natural energy resource compared to fos-sil fuels. Regarding the limited amount of fuels such as coal and petroleum and their eﬀect on nature, any application that has the ability to harvest the sun-light and produce energy becomes extremely important. One of the potential mechanisms that can remedy the energy demand in the future is photocatal-ysis, and two-dimensional (2D) materials with suitable electronic and optical properties oﬀer new possibilities for photocatalytic applications. Although vari-ous 2D materials have hitherto been speciﬁed as adequate candidates, materials with high photocatalytic eﬃciency for water splitting are still minimal. In this regard, a novel 2D Janus GePAs monolayer is predicted and its capability for photocatalytic water splitting is examined by performing ﬁrst-principles density functional theory. The GePAs monolayer is shown to possess robust dynamic and thermal stability. The direct electronic band gap in the visible region and band edge positions of the strain-free and strained monolayers are revealed to be convenient for redox reactions in wide pH ranges. The low recombination proba-bility of charge carriers ensured by high and anisotropic carrier mobility enhances the material’s photocatalytic potential. Optical response calculations, including many-body interactions, exhibit signiﬁcant optical absorption capacity in the UV–visible range. Furthermore, ultra-low exciton binding energy facilitates dis-sociation into free electrons and holes, promoting photocatalytic reactions. Our study suggests GePAs monolayer is an ideal and remarkably promising material to be utilized in visible-light-driven photocatalytic applications.
Open Access
Synthesis of magnetically anisotropic janus particles by droplet-based microfluidics
(2024-01) Saqib, Muhammad
In the past decade Janus particles have been extensively utilized by the scientific community for potential uses such as cell encapsulation and assembly, DNA assays, biological multiplexing , targeted drug delivery, noninvasive imaging, theranostics, microlenses, reflection-mode displays, removal of organic and metal pollutants and water decontamination. Due to their multi functional characteristics, stemming from their anisotropy, they are superior to conventional monophase particles. Even though there are several established synthesis methods for Janus particles, microfluidics-based methods are by far the most convenient and reliable due to low reagent consumption, monodispersity of the resultant particles and efficient control over reaction conditions. Droplet-based microfluidics is the most popular technique for the reliable synthesis of Janus particles and even though it has been extensively explored there are many aspects of the conventional droplet-based microfluidics techniques that either result in poor anisotropy of the synthesized particles or involve off-chip processing. In this work a simple and novel droplet-based microfluidic technique is utilized to synthesize magnetically anisotropic Janus particles. Using this method magnetically anisotropic Janus particles are synthesized by using droplets as templates. The droplets contain magnetic nanoparticles and are exposed to ultraviolet radiation while passing through a magnetic field. The magnetic field renders the droplet anisotropic by attracting the magnetic nanoparticles to one hemisphere while at the same time the ultrviolet exposure initiates polymerization of the prepolymer phase. The microfluidic device was optimized by using numerical simulations and experimental observations. The magnetic flux density was optimized by using a magnetic flux density map. The synthesized particles were imaged under an optical microscope to observe their size distribution and scanning electron microscope to confirm complete polymerization and the magnetic anisotropy was confirmed by observing the motion of the particle in the presence of an external magnetic field. The synthesized particles were observed to be monodisperse and exhibited rotation about their own axis which is characteristic of magnetically anisotropic particles. Further another design was developed to merge droplets from two dispersed phase streams in a Janus orientation by optimizing the angle of merging. With this device the merged droplet was observed to contain the constituents of its two hemispheres distinct from each other. Using this device TiO2-Fe2O3 and SiO2- Fe2O3 magnetically anisotropic Janus particles were synthesized. The synthesized Janus particles were observed under the optical microscope and the scanning electron microscope. Moreover the magnetic response of the Janus particles was also observed using a permanent magnet. These types of Janus particles could be potentially used as micromotors for microcargo transport because of their magnetic properties or for DNA assay applications.