Sumit Saxena

Indian Institute of Technology Bombay | IIT Bombay · Department of Metallurgical Engineering & Materials Science Including Corrosion Science & Engineering

The particular spectroscopic characteristics of materials in the terahertz region (0.1 THz to 10 THz) provides a powerful tool for material detection and identification. The electrical, optical, and dielectric properties of materials have been investigated through terahertz time-domain spectroscopy (THz-TDS). The purpose of this research is to prop...

Photocatalytic degradation is an advanced process which utilizes light for degradation of organic pollutants. In this study, we have investigated the photocatalytic properties of reduced siloxene nanosheets for the removal of dyes from wastewater. Reduction of siloxene resulted in a decreased bandgap from 2.7 to 2.3 eV, allowing for better absorpti...

Diabetes is a global pandemic that increases the risk of various health complications, including heart attacks, renal failure, blindness, stroke, and peripheral neuropathy. Type-2 Diabetes (T2D) results from an imbalance in lipid and glucose metabolism due to hostility to insulin action and insufficient insulin production response. Valine amino aci...

The study delves into the comprehensive exploration of ceria nanoparticle synthesis, explicitly focusing on distinct variants: fuel-rich, fuel-deficient, and stoichiometric proportions. These ceria variants are meticulously investigated using the sol-gel combustion method to uncover their unique characteristics. The exceptional performance of stoic...

Due to the intermittence nature of renewable sources of energy, the research community has paid close attention to energy storage devices for ensuring the continuous supply of energy. Among the other transition metal oxides, V 2 O 5 nanostructures have some inherent properties such as their layered structure, numerous oxidation states, low cost, ea...

The development of high-performance energy storage devices is crucial for various applications, such as electric vehicles, portable electronics, and renewable energy systems. Supercapacitors have emerged as a promising technology due to their high power density and long cycle life. However, their low energy density has limited their widespread appl...

Development of energy storage devices of high energy density and long cycle life is one of the pressing needs of electronic devices. Pseudo-capacitors with iron oxide electrodes show promising energy storage devices because they are economical and safe, but have poor conductivity and stability. To achieve an improved electrochemical performance suc...

Abstract Janus nanosystems enable one to achieve complementary properties in a single entity. In the current study, the fundamental properties like structural, electronic, and dynamical of Janus hexagonal boron nitride (h‐BN) by selectively hydrogenating and fluorinating a h‐BN surface are systematically examined, using density functional theory. F...

The goal of the present study is to explore how the size and functionalization of graphene quantum dots (GQDs) affect their sensing capabilities. Specifically, we investigated the adsorption of SO$_2$, SOF$_2$, SO$_2$F$_2$, and SF$_6$ on GQDs that were functionalized with -CH$_3$, - COCH$_3$, and -NH$_2$. We used density functional theory to analyz...

The goal of present study is to explore how the size and functionalization of graphene quantum dots (GQDs) affect their sensing capabilities. Specifically, we investigated the adsorption of SO2, SOF2, SO2F2, and SF6 on GQDs that were functionalized with –CH3, –COCH3, and –NH2. We used density functional theory to analyse the electronic properties o...

Hybrid nanocomposites with performance are prepared using II–VI semiconductors and polymers. The II–VI semiconductor-polymer nanocomposite has advantage of both the II–VI semiconductors and polymers. The most important features of II–VI semiconductor nanomaterials are increased surface-to-volume ratio, bandgap modulation and catalytic behaviour. Th...

Two-photon lithography (TPL) is a versatile technology for additive manufacturing of 2D and 3D micro/nanostructures with sub-wavelength resolved features. Recent advancement in laser technology has enabled the application of TPL fabricated structures in several fields such as microelectronics, photonics, optoelectronics, microfluidics, and plasmoni...

Macroalgae are a diverse group of primary producers that offer indispensable ecosystem services towards bacterial colonization and proliferation in aquatic biomes. Macroalgae/bacteria interactions are complex in natural biomes and contribute mutually to their growth and biotechnological outcomes. Most findings on macroalgae-associated bacteria and...

We report the 4D printing of a miniaturized organo-arsenic sensor by femtosecond laser-assisted two-photon lithography. Fluorescence turn-on detection of organo-arsenic species was achieved at ppb levels.

Simultaneous silver salt reduction and deposition at specific sites of graphene oxide films by femtosecond laser irradiation is achieved and Raman analysis corresponding to varying concentration of silver salt loading is investigated.

Carbon quantum dots have been implemented as two-photon initiators, and rapid prototyping of optically active micro/nanostructures has been demonstrated.

We report the fabrication of functionalized microresonator in a single step by using two-photon lithography. Surface-engineered carbon quantum dots have been used as a sensing material in the microresonators, exhibiting affinity towards the heavy metal ion.

Contamination of water by oil poses a significant risk to the entire ecosystem and has led to the development of advanced materials and processes for its remediation. Current membrane based...

We report the fabrication of all-dielectric, 3D chiral metamaterial using two-photon lithography, addressing the limitations of metallic metamaterial. The electromagnetic behaviour of the structure has been numerically studied using COMSOL.

We have demonstrated a technique for the fabrication of two-dimensional photonic crystal slab using femtosecond laser-assisted two-photon lithography. The fabricated structure holds potential for waveguiding applications.

Two-photon active carbon quantum dots have been exploited as initiators to induce two-photon polymerization for additive manufacturing of dielectric metamaterials.

ZnO nanopillar array was fabricated by femtosecond laser direct writing in ZnO quantum dots thin film. This work provides a facile method for patterning high permittivity nanostructures with tunable optical properties by varying fabrication parameters.

Optimal exposure conditions in two-photon polymerization-based additive manufacturing have been systematically investigated for the fabrication of functional three-dimensional structures in additive-free resin. The realization of complex micro-rotors has been demonstrated using the optimal process parameters.

Two-photon polymerization has been exploited to generate micro replicas of bioinspired structures. As a proof-of-concept a star-fish shaped micro-replica has been demonstrated, with high replication fidelity in acrylate-based photo-resin.

Emissive micro-ring resonators have been additively manufactured using femtosecond laser assisted non-linear photopolymerization of acrylate based resin in a single exposure step. Such optically active structures find application in the field of optics and photonics.

The major bottleneck in harnessing the potential of solid-solid interfacial hetero structures involves incoherent interface constructions and complicated synthesis approaches. In this context, a synthesis strategy involving in situ interfacial manipulation of imidazole-bridged one-dimensional single-crystalline nanoribbons is developed through the...

Engineered 3Dnanostructures have played a crucial role in the development of modern electronic devices. However, the demand for higher dimensional nanostructures have become a necessity for the development of superior next generation miniaturized devices. Traditional two-photon femtosecond laser-based fabrication techniques have enabled fabrication...

Water scarcity due to inefficient recycling processes and pollution of water bodies have directly affected the lives and livelihood of around 600 million people globally. Textile industries dump gallons of untreated waste such as dyes, organic reagents, toxic chemicals in surface water. Treating such effluents is a multi-stage process and needs to...

Density functional theory (DFT) can be quite advantageous in advancing the field of catalysis because of the microscopic insights it provides, and thus can guide experimental searches of novel catalysts. Several recent works have demonstrated that low-dimensional materials can be very efficient catalysts. Graphene quantum dots (GQDs) have gained mu...

Rapid advances in the field of catalysis require a microscopic understanding of the catalytic mechanisms. However, in recent times, experimental insights in this field have fallen short of expectations. Furthermore, experimental searches of novel catalytic materials are expensive and time-consuming, with no guarantees of success. As a result, densi...

Release of liquefied hydrocarbons in domestic and industrial effluents, along with oil spills cause significant adverse effects on the soil, water, aquatic ecosystem, and humans. Thus, selective and cost-effective technology to address this challenge is highly desirable. Here, we report the fabrication of electrospun polyvinyl alcohol (PVA) membran...

Surface modification of membranes for oil–water separation has been a topic of significant interest due to disastrous impact of oil spills on the environment. In general, porous membranes used for the separation suffer from low flexibility are prone to corrosion, fast degradation, poor mechanical, and thermal stability. We report surface-modified n...

We report fabrication of fluorescent micro/nanostructure by two-photon polymerization of sartomer (SR) with doped-carbon quantum dots for attomolar dimethylarsinate(DMA) detection. Fluorescent selective detection in picomolar range (50-300pM) was achieved followed by sensor fabrication (area~100μm 100μm).

A sequential combination of two-photon lithography and molding process has been utilized to develop large-scale production of nanopatterned tags.

Microplastics are tiny fragments of plastic material classified as primary and secondary counterparts based on the source material. Human exposure level studies and bioaccumulation potential of such secondary microplastics from regular products lack supported scientific findings to claim the consequences of consuming such particles. In this study,...

This letter reports an inorganic/organic heterojunction photodetector using n-type zinc oxide nanorod array (NRA) and p-type poly3,4-ethylenedioxythiophene: polystyrene sulfonate (PEDOT:PSS). ZnO NRA is grown hydrothermally on the ZnO quantum dots (QDs) seed layer deposited on indium tin oxide (ITO) substrate. Further, ZnO NRA is treated with ZnO Q...

Two-photon lithography has emerged as a tool of prime importance for additive manufacturing of 2D and 3D micro/nanostructures in metal-polymer composite resins with resolutions beyond the diffraction limit. Two-photon absorption dyes used are not only expensive, difficult to synthesize but also proprietary. To mitigate these challenges, we report f...

Anti-counterfeiting tags are a simple and easy way to avoid duplication/forgery of valuable products; however, counterfeiting has evolved over time, with the help of newer technologies to clone and reproduce exact signatures, tags, barcodes, etc that are difficult to identify. To prevent such counterfeiting, it is imperative to obtain advanced and...

High-quality nitrogen-doped carbon quantum dots (NCQDs) are synthesized using domestic microwave-assisted pyrolysis method. These show excellent physiochemical and optical properties such as wide spectral adsorption, high charge carrier extraction, fast charge carrier transportation, and tuneable emission. These NCQDs are introduced in the dye sens...

Graphene based materials have become the materials of choice for sensing applications due to their large surface area, high electrical conductivity and their ability to interact with various chemical species. Heavy metals bind with proteins and pose a potential risk to human life when exposed to higher concentrations. Thus, precise and quick detect...

Reduced graphene oxide or rGO, a much studied 2D material, is a chemical equivalent of graphene. rGO has been extensively studied in the field of wide variety of electrochemical, optical and spectroscopic sensors for accurate and selective detection of heavy metals in water. Lead (Pb (II)) is one of the most toxic heavy metals which causes numerous...

Carbon is one of the most versatile elements in the periodic table and is known to occur in various allotropic forms. It has been widely explored since the eighteenth century and its investigation in various forms has witnessed continuous growth thereafter. The effect of these advancements has guided numerous discoveries which have not only address...

Functional metastructures exhibiting unique optical properties are desirable for advancements in microfluidics, optoelectronics, nonlinear photonics, biochemical sensing, and metamaterials. Additive manufacturing techniques are expected to enable rapid prototyping of complex 3D architectonics required for such applications. We report the fabricatio...

Biodegradable plastics are recent most-sought engineered materials disrupting single-use plastics worldwide. It implies onto commercial applications such as packaging, cosmetics, consumer electronics and biomedical industries. These polymers are either made up of aliphatic polyesters with ester units or aliphatic-aromatic polyesters with few aromat...

Nearly 80% of oceanic plastic waste is from land-based sources including degradable polymers. The recent trend towards the use of degradable polymers in the form of photodegradable and biodegradable polymers promises to be a sustainable solution to plastic pollution, whereas microplastics (MPs) impose higher ecological risk due to limited knowledge...

Extensive industrialization and urbanization have adversely affected the quality of consumable water on the earth. The industrial effluents are the major source of micropollutants such as heavy metals, which deteriorates the environment making it toxic to the flora and fauna sustaining in the water. Heavy metals such as lead, cobalt, arsenic, chrom...

Recent development in two-dimensional materials is due to their exceptional performances in the field of electronics and optical devices in the nano regime. First principles investigation based on density functional theory is used to predict the existence of Li2O in two-dimensional hexagonal monolayer flatlands. Li2O is found to be in H- and T-phas...

Silicon based materials on 2D landscape are gaining significant interest due to their exotic properties along with well-developed processing technologies. We report use of 2D siloxene nanosheets as a potential photocatalyst for remediation of water polluted from cationic dyes. Degradation of methylene blue (MB) is used as a representative case stud...

Tailoring of surface-enhanced materials is vital towards achieving enhanced energy storage. In order to achieve this, hybrid material combinations often used in traditional vertically stacked morphologies. However, the inherent nature of poor conductivity and aggregation results in a bottleneck in exploiting such materials' full potential. In parti...

Functional materials with designer morphologies are anticipated to be the next generation materials for energy storage applications. In this manuscript, we have developed a holistic approach to enhance the surface area and hence the properties of nanostructures by synthesizing coronal nanohybrids of graphene. These nanohybrids provide distinctive a...

Simultaneous two photon polymerization/reduction of metal-polymer composite resin has been utilized for fabrication of microstructures with silver loadings as high as 20 wt%. Feature Sizes as small as 370 nm are demonstrated.

We demonstrate femtosecond laser based fabrication of unclonable micro-quick response code with fluorescent attributes for anti-counterfeiting applications. 3D nano-features in the codes provides security against duplication.

Two-photon polymerization assisted fabrication of fluorescene encoded, cloaked nanopatterned labels, embedded in non emissive polymer bed has been demonstrated for anti-counterfeiting application.

The interplay of resolution and strength of submicron structures in femtosecond laser-based writing is an important parameter that has prominent effects on the designated applications. We have shown the strength-resolution interplay for epoxy-based resin.

Graphene oxide-based thin films are constructed and subjected to LASER light for photo reducing and patterning structures on them and are studied to make building blocks for graphene-based metamaterials.

Silicon, a hard brittle crystalline solid is tetravalent metalloid and prominently well known in the semiconductor community. Although silicon has been a material of choice for energy generation in silicon solar cells, its high theoretical lithium storage capacity makes it one of the most promising anode materials for development of high performanc...

It is well-known that confinement effects in graphene nanoribbons have a significant effect on the electronic and transport properties of graphene. These properties of pristine graphene nanoribbons have been studied theoretically as well as experimentally. Here, we report the transport properties of oxidized zigzag graphene nanoribbons by using den...

We present fabrication of subwavelength plasmonic gratings by two photon enabled simultaneous photopolymerization and photoreduction of gold doped acrylate resin. The results indicate the progress towards realization of 3D plasmonic metamaterials.

Here we present single step, microwave assisted synthesis of nitrogen doped carbon quantum dots (N-CQDs). The varied proportions of the carbon and nitrogen precursors revealed the dependency of the photophysical properties on the surface states of N-CQDs.

We report plasmonic enhancement of Raman signal by employing silver nanotriangles to detect methylene blue in concentrations below 10 ⁻⁵ M. The characteristic morphology and dimensions have helped in producing an enhancement even at low power.

We have demonstrated the fabrication of microstructures in a naturally derived, biodegradable, non-toxic polymer, chitosan, using two-photon lithography. The fabricated structure can be employed in applications ranging from biology to nano-photonics.

Functionalization of graphene-based materials using chemical moieties not only modify the electronic structure of the underlying graphene but also enable in limited enhancement of targeted properties. Surface modification of graphene-based materials using other nanostructures enhances the effective properties by minimally modifying the properties o...

Rapid advancements in technology has led to urgent requirement for mobile and portable power sources. Achieving self-sustainability using renewable energy sources using such devices provide an added advantage. Electrode materials play a critical role in performance of these devices, while the surface morphology of the electrode material play a cruc...

The extraordinary success of graphene in various applications has led to the quest to innovate techniques for production and patterning of nanomaterials. Numerous techniques such as vapor deposition, epitaxial growth, mechanical and chemical exfoliation have been explored to achieve this goal. These new methods have enabled the synthesis of a monol...

The electronic and transport properties in an antiferromagnetic junction of edge functionalized stanene nanoribbons (SnNRs) were studied using first-principle density functional theory. The behaviour of quantum conductance at zero bias voltage with varying ribbon widths in bare and edge hydrogenated SnNRs is demonstrated. The conductance gap near t...

The discovery of graphene oxide has made profound impact in varied areas of research due to its excellent physico-chemical properties. However, surface engineering of these nanostructures hold the key to enhanced surface properties. Here we introduce surface engineering of rGO shells by radially grafting Ni-Co LDH lamella on rGO shells to form Ni-C...

The rational design and fabrication of nanostructured materials with desired electrochemical performance is highly demanded for energy storage applications. Functionalization of graphene based materials using chemical moieties not only alter the electronic structure of the underlying graphene but also enable in only limited enhancement of targeted...

Nanopowder samples of terbium aluminum garnet (TAG) doped with Ce and Eu were prepared by a sol–gel technique followed by sintering in air at various temperatures (maximum of \(1100{^{\circ }}\hbox {C}\)). The investigated concentrations of both the dopants were 0.1, 0.5 and 1.0 mol%. Nine powder samples prepared by the permutation of the doping co...

Metamaterials are engineered materials that offer the flexibility to manipulate the incident waves leading to exotic applications such as cloaking, extraordinary transmission, sub-wavelength imaging and negative refraction. These concepts have largely been explored in the context of electromagnetic waves. Acoustic metamaterials, similar to their op...

Extraordinary properties of graphene and its derivatives have found application in varied areas such as energy, electronics, optical devices and sensors, to name a few. Large surface area along with specialized functional groups make these materials attractive for removal of dye molecules in solution via adsorption. Industrial effluents contain lar...

ZnO nanophosphor doped with 0.5mol % of Tb was prepared by precipitation method followed by sintering in air at 700°C. The doping of Tb in ZnO was confirmed by EDX while the powder XRD showed the characteristic wurtzite structure of ZnO implying that the crystal structure of ZnO did not change on doping with 0.5 mole%Tb. This conclusion was further...

Gd (0.1, 0.5, 1.0 mol%) doped ZnO nano phosphor, prepared by wet chemical method followed by sintering in air at 700 °C, was characterized by XRD, EDX, SEM, and photoluminescence techniques. EDX confirmed the doping of Gd in ZnO, while XRD patterns showed that the ZnO wurtzite crystal structure remained unchanged on doping. Nanostructure nature of...

The electronic and transport properties of graphene nanoribbons strongly depends on different types of adatoms. Oxygen as adatom on graphene is expected to resemble oxidized graphene sheets and enable in understanding their transport properties. Here, we report the transport properties of oxygen adsorbed zigzag edge saturated graphene nanoribbon. I...

Broad emission in the spectral region 400-700nm has been observed from ZnO nanophosphor co-doped with Ce, Eu and Tb; dopent concentrations used were 0.1, 0.5 and 1.0 mol%. Room temperature powder XRD and FTIR investigations showed that ZnO structure was unchanged on doping. EDX confirmed that the dopents entered the ZnO lattice.

The presence of azo dye molecules in effluents is a source of water pollution and an environmental hazard. Thus, it is very important to separate out such dye molecules. We have investigated the use of graphene oxide (GO) for the purification of dye-contaminated water. The adsorption efficiency of GO in the degradation of azo dye molecules and the...

Successful synthesis of graphene has created a runaway effect in the exploration of other similar two-dimensional materials. These materials are important as they provide large surface areas and have led to the exploration of new physical phenomena. Even though graphene has exotic electronic properties, its spin-orbit coupling is very weak. Tin, be...