Publications by Virendra Kumar Parashar

Multi-photon polymerization using upconversion nanoparticles for tunable feature-size printing

Martinus Gijs, Virendra Kumar Parashar, Christophe Moser, Antoine Vincent Boniface

The recent development of light-based 3D printing technologies has marked a turning point in additive manufacturing. Through photopolymerization, liquid resins can be solidified into complex objects. Usually, the polymerization is triggered by exciting a p ...

WALTER DE GRUYTER GMBH2023

Ripening of two-dimensional colloidal CdSe nanocrystals into zero-dimensional nanodots

Martinus Gijs, Virendra Kumar Parashar, Xiaopeng Huang

Understanding the ripening of two-dimensional (2D) colloidal nanocrystals (NCs) is important for the controllable synthesis of NCs with desired morphology and properties. In this study, we systematically investigate the ripening behavior of the 2D CdSe NCs ...

CELL PRESS2021

Insight into the Growth of Anisotropic CdSe Nanocrystals: Attachment of Intrinsically Different Building Blocks

Martinus Gijs, Virendra Kumar Parashar, Xiaopeng Huang

An in-depth understanding of the growth mechanism of nanocrystals (NCs) is of great significance for shape control of colloidal semiconductor nanostructures. In this study, we elucidate the formation mechanism of anisotropic CdSe NCs by systematically inve ...

AMER CHEMICAL SOC2020

Spontaneous Formation of CdSe Photoluminescent Nanotubes with Visible-Light Photocatalytic Performance

Martinus Gijs, Virendra Kumar Parashar, Xiaopeng Huang

Two-dimensional (2D) colloidal CdSe nanocrystals (NCs) with precise atomic-scale thickness have attracted intensive attention in recent years due to their optical properties and quantum confinement effects originating from their particular band structure. ...

2019

Dimensional tailoring of hydrothermally grown zinc oxide nanostructures in a continuous flow micro reactor

Martinus Gijs, Virendra Kumar Parashar

Dynamic deposition of ZnO nanostructures with varying morphologies (nanorods, nanocones, nanopencils, nanosheets, etc.), diameters, lengths and aerial densities on ITO-PET substrates has been achieved using a continuous flow microreactor in which we mainta ...

Royal Society of Chemistry2018

Nucleation and Growth Behavior of CdSe Nanocrystals Synthesized in the Presence of Oleylamine Coordinating Ligand

Martinus Gijs, Virendra Kumar Parashar, Xiaopeng Huang

We established the dual role played by oleylamine (OAm) during the synthesis of CdSe nanocrystals (NCs) by the hot injection method. Earlier reports suggest its role either as nucleating or as passivating agent in controlling the growth of CdSe NCs. Remark ...

2018

Synergistic effect of carboxylic and amine ligands on the synthesis of CdSe nanocrystals

Martinus Gijs, Virendra Kumar Parashar

We demonstrate the drastic improvement in absorbance and photoluminescence (UV-PL) of CdSe nanocrystals (NCs) upon adding both a carboxylic acid and an amine ligand to the cadmium acetate green chemistry source. We combined carboxylate complexes of lauric ...

Royal Soc Chemistry2016

Spherical superstructures of oxide nanoparticles for catalytic reactions in microchemical reactors

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker

We report the fabrication of spherical superstructures composed of SiO2 and TiO2 nanoparticles and their applications in catalyzing organic reactions. Assembling of the nanoparticles into superstructures is done by heating a water-in-oil micro-emulsion, wh ...

Elsevier Science Bv2015

A microfluidic process for on-chip formation of assemblies of oxide nanoparticles

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker, Danut Necula

We report the continuous growth of spherical assemblies of silica and titania nanoparticles, which were pre-activated to produce hydroxyl/ peroxy groups on their surface, by flowing a colloid-in-dioctyl phthalate emulsion into a polydimethylsiloxane microf ...

Royal Soc Chemistry2014

Large spherical assemblies of oxide nanoparticles

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker

2014

Controlled synthesis of fluorescent silica nanoparticles inside microfluidic droplets

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker, Ioannis Lignos

We study the droplet-based synthesis of fluorescent silica nanoparticles (50–350 nm size) in a microfluidic chip. Fluorescein-isothiocyanate (FITC) dye is first chemically linked to aminopropyl triethoxysilane (APTES) in ethanol and this reaction product i ...

Royal Society of Chemistry2012

Grafting submicron titania particles with gold nanoparticles using droplet microfluidics

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker

A microfluidic method to synthesize gold–titania nanocomposites is presented. Porous TiO2 particles are first loaded with a reducing agent and then suspended in water and mixed with chloroauric acid (HAuCl4) in a droplet-by-droplet manner on a microfluidic ...

2012

Anisotropic Magnetic Porous Assemblies of Oxide Nanoparticles Interconnected Via Silica Bridges for Catalytic Application

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker

We report the microfluidic chip-based assembly of colloidal silanol-functionalized silica nanoparticles using monodisperse water-in-oil droplets as templates. The nanoparticles are linked via silica bridges, thereby forming superstructures that range from ...

American Chemical Society2011

Exotic droplets formed in microfluidic chips with uniform wettability

Martinus Gijs, Virendra Kumar Parashar, Cédric Razaname, Josias Basil Wacker, Guillaume Louis

Microdroplets are widely used in industrial processes. In the absence of external forces, droplets generally assume a spherical shape. Here, we present two methods to form non-spherical droplets in microfluidic glass chips. A uniformly hydrophobized chip h ...

Elsevier2011

From particles to pillars: on-chip synthesis of silica nanoparticle assemblies with controlled shape and size

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker

We describe the assembly of silica nanoparticles into superstructures with controlled shape and size. The individual nanoparticles are chemically linked to each other via silica bridges, thus providing high mechanical stability to the assembly. Key to cont ...

IEEE2011

Controlled Microsynthesis of Silica Particles in a Microfluidic Setup

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker

We report on a novel microsynthesis method for easy controlling the size of silica micro- and nanoparticles. Colloids are synthesized in a microfluidic chamber by layer-wise adsorption of silica to precipitated nuclei. We prepare samples of spherical parti ...

Elsevier Science, Reg Sales Off, Customer Support Dept, 655 Ave Of The Americas, New York, Ny 10010 Usa2009

Influence of Oil Type and Viscosity on Droplet Size in a Flow Focusing Microfluidic Device

Martinus Gijs, Virendra Kumar Parashar, Josias Basil Wacker

We form water-in-oil droplets in a microfluidic channel-nozzle geometry for studying the influence of viscosity of oil and of different oil classes on the droplet size. We find that the chemical structure of oil dominates over its viscosity. Our studies ar ...

Elsevier Science, Reg Sales Off, Customer Support Dept, 655 Ave Of The Americas, New York, Ny 10010 Usa2009

Fabrication of microfluidic mixers with varying topography in glass using the powder blasting process

Abdeljalil Sayah, Martinus Gijs, Virendra Kumar Parashar

The powder-blasting method is used to fabricate structures with a three-dimensional topography in glass using elastomeric masks. The relation between the mask opening width and the erosion depth is exploited to fabricate microstructures with varying depth ...

2009

In situ fabrication of a polyacrylamide membrane in a microfluidic channel

Martinus Gijs, Virendra Kumar Parashar, Jean-Baptiste Robert Orhan

We present a novel technological approach for the in situ realization of a micron-thin poly-acrylamide membrane in the center of a microfluidic channel. The membrane is formed by interfacial polymerization of an inner stream of monomer solution in between ...

2008

Borosilicate nanoparticles prepared by exothermic phase separation

Abdeljalil Sayah, Martinus Gijs, Virendra Kumar Parashar, Jean-Baptiste Robert Orhan

2008