Nanogold Foundry Involving High-Shear-Mediated Photocontact Electrification in Water.

Controlling the size and morphology of gold nanoparticles occurs in the absence of added reducing agents or other excipients such as surfactants, on UV irradiation ( 254 nm) of aqueous auric acid (H[AuCl]) in a thin film of liquid in a vortex fluidic device (VFD) within a rapidly rotating tilted quartz tube. This involves contact electrification (CE), which occurs at the solid-liquid interface with the oxidation of water photoinduced, forming the hydroxyl radical, OH. In air, the redox couple is reduction of O to the superoxide radical anion, O , which then reduces Au to elemental gold, as does other reactive oxygen species present, competing with CE reduction of Au.

Room-Temperature Vortex Fluidic Flow Chemistry Synthesis of Full Color Carbon Dots.

Carbon dots (CDs) as a new class of photoluminescent zero-dimension carbon nanoparticles have attracted significant research interests owing to their extraordinary opto-electro-properties and biocompatibility. So far, almost all syntheses of CDs require either heat treatment or exertion of high energy fields. Herein, a scalable room-temperature vortex fluidic method is introduced to the CDs synthesis using the angled vortex fluidic device (VFD).

Free-Standing Nanocomposite Au@Graphene Oxide Continuous Flow Synthesis in Water for Degradation of Organic Dyes.

We have developed a rapid and facile method for preparing free-standing nanocomposite of gold nanoparticles with graphene oxide (Au@GO) in water under continuous flow in the absence of harsh reducing agents and any other auxiliary substances, as a method with favourable green chemistry metrics. This uses a vortex fluidic device (VFD) where induced mechanical energy and photo-contact electrification associated with the dynamic thin film in the rapidly rotating tube tilted at 45° while simultaneously UV irradiated (λ=254 nm, 20 W) results in decomposition of water to hydrogen and hydrogen peroxide with growth of the gold nanoparticles on the surface of the GO. We have established that the resulting Au@GO composite sheets rapidly catalyse the degradation of commercial dyes like methyl orange (MO) and methylene blue (MB) using the hydrogen peroxide generated in situ in the VFD.

Highly Uniform Nanodiamond-Graphene Composites Microspheres for Electrocatalytic Hydrogen Evolution.

To progress the clean hydrogen-gas-based energy economy, there is a demand for cost-effective, highly efficient catalysts to facilitate the hydrogen evolution reaction process (HER). Due to the amazing catalytic capabilities of two-dimensional materials, extensive research has been done on these structures. However, most of the described syntheses take a lot of time, are challenging, and are ineffective.

High conversion continuous flow exfoliation of 2D MoS.

We report a low-cost and highly efficient process for exfoliating of MoS using an energy efficient vortex fluidic device (VFD). This method is high in green chemistry metrics in avoiding the use of auxiliary substances, and the process is scalable, with a conversion of as received MoS into 2D sheets at ∼73%.

Sub-micron moulding topological mass transport regimes in angled vortex fluidic flow.

Shear stress in dynamic thin films, as in vortex fluidics, can be harnessed for generating non-equilibrium conditions, but the nature of the fluid flow is not understood. A rapidly rotating inclined tube in the vortex fluidic device (VFD) imparts shear stress (mechanical energy) into a thin film of liquid, depending on the physical characteristics of the liquid and rotational speed, , tilt angle, , and diameter of the tube. Through understanding that the fluid exhibits resonance behaviours from the confining boundaries of the glass surface and the meniscus that determines the liquid film thickness, we have established specific topological mass transport regimes.

High-Yield Continuous-Flow Synthesis of Spheroidal C@Graphene Composites as Supercapacitors.

Graphene spheres confining fullerene C are quantitatively formed under high-shear and continuous-flow processing using a vortex fluidic device (VFD). This involves intense micromixing a colloidal suspension of graphite in DMF and an -xylene solution of C at room temperature in the absence of surfactants and other auxiliary substances. The diameters of the composite spheres, C@graphene, can be controlled with size distributions ranging from 1.

Vertically aligned laser sliced MWCNTs.

Applications of multi-walled carbon nanotubes (MWCNTs) benefit from the availability of specific lengths of the material while keeping the outer walls pristine, for example, for applications requiring vertically aligned tubes. To this end, a simple and effective continuous flow 'top down' process to control the length of sliced MWCNTs has been developed using a vortex fluidic device (VFD) coupled with a 1064 nm pulse laser, with the process in the absence of chemicals and any auxiliary substances. Three different length distributions of the sliced MWCNTs, centered at 75 ± 2.

Continuous flow photolytic reduction of graphene oxide.

Reduced graphene oxide (rGO) is generated from GO dispersed in water under continuous flow in the absence of harsh reducing agents, in a vortex fluidic device, such that the processing is scalable with uniformity of the product. This involves simultaneously UV irradiating (λ = 254 nm, 20 W) the dynamic thin film in the rapidly rotating glass tube in the microfluidic platform. The rGO is comparable to that formed using waste generating chemical based processing, with a film of the material having a resistance of 2.

Laser-Ablated Vortex Fluidic-Mediated Synthesis of Superparamagnetic Magnetite Nanoparticles in Water Under Flow.

Selective formation of only one iron oxide phase is a major challenge in conventional laser ablation process, as is scaling up the process. Herein, superparamagnetic single-phase magnetite nanoparticles of hexagonal and spheroidal-shape, with an average size of ca. 15 nm, are generated by laser ablation of bulk iron metal at 1064 nm in a vortex fluidic device (VFD).

Three-step-in-one synthesis of supercapacitor MWCNT superparamagnetic magnetite composite material under flow.

Composites of multi-walled carbon nanotubes (MWCNTs) and superparamagnetic magnetite nanoparticles, FeO@MWCNT, were synthesized in DMF in a vortex fluidic device (VFD). This involved generation of the iron oxide nanoparticles by laser ablation of bulk iron metal at 1064 nm using a pulsed laser, over the dynamic thin film in the microfluidic platform. The overall processing is a three-step in one operation: (i) slicing MWCNTs, (ii) generating the superparamagnetic nanoparticles and (iii) decorating them on the surface of the MWCNTs.

Inverted vortex fluidic exfoliation and scrolling of hexagonal-boron nitride.

Exfoliation or scrolling of hexagonal boron nitride (h-BN) occurs in a vortex fluidic device (VFD) operating under continuous flow, with a tilt angle of -45° relative to the horizontal position. This new VFD processing strategy is effective in avoiding the build-up of material that occurs when the device is operated using the conventional tilt angle of +45°, where the h-BN precursor and scrolls are centrifugally held against the wall of the tube. At a tilt angle of -45° the downward flow aided by gravity facilitates material exiting the tube with the exfoliation of h-BN and formation of h-BN scrolls then optimized by systematically varying the other VFD operating parameters, including flow rate and rotational speed, along with concentration of h-BN and the choice of solvent.

Vortex fluidic mediated transformation of graphite into highly conducting graphene scrolls.

Two-dimensional graphene has remarkable properties that are revolutionary in many applications. Scrolling monolayer graphene with precise tunability would create further potential for niche applications but this has proved challenging. We have now established the ability to fabricate monolayer graphene scrolls in high yield directly from graphite flakes under non-equilibrium conditions at room temperature in dynamic thin films of liquid.

Controlling the growth of fullerene C cones under continuous flow.

Micromixing of an o-xylene solution of C60 with N-N-dimethylformamide (DMF) at room temperature under continuous flow in a vortex fluidic device (VFD) results in the formation of symmetrical right cones in high yield with diameters 0.5 to 2.5 μm, pitch angle 25° to 55° and wall thickness 120 to 310 nm.