Thumu Udayabhaskararao

Thumu Udayabhaskararao
University of Electronic Science and Technology of China | UESTC · Institute of Fundamental and Frontier Sciences

PhD

About

65
Publications
7,786
Reads
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2,824
Citations
Additional affiliations
November 2017 - January 2019
International Iberian Nanotechnology Laboratory
Position
  • Established Marie Curie Research Fellow
May 2017 - October 2017
Weizmann Institute of Science
Position
  • Intern
January 2016 - May 2017
Weizmann Institute of Science
Position
  • Fellow
Education
July 2006 - May 2013
June 2004 - May 2006
Andhra University
Field of study
  • Physical Chemistry

Publications

Publications (65)
Article
Full-text available
Among perovskites, the research on cesium lead iodides (CsPbI3) has attracted a large research community, owing to their all-inorganic nature and promising solar cell performance. Typically, the CsPbI3 solar cell devices are prepared at various heterojunctions, and working at fluctuating temperatures raises questions on the material stability-relat...
Article
In most synthetic nanoreactor systems, catalysed products do not promptly diffuse away from the nanoreactor, which leads to lower than expected catalytic efficiencies. To address the diffusion problem, transient polymer micelle nanoreactor systems were achieved using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as the fuel and activated este...
Article
Full-text available
The rediscovery of the halide perovskite class of compounds and, in particular, the organic and inorganic lead halide perovskite (LHP) materials and lead-free derivatives has reached remarkable landmarks in numerous applications. First among these is the field of photovoltaics, which is at the core of today’s environmental sustainability efforts. I...
Article
Epoxy resins have highly appreciable design flexibility, good mechanical, thermal, chemical properties and also compatible with a wide variety of reinforcement materials. These excellent properties make epoxy resin as a choice resin for many high-performance engineering applications. Despite their high performances, there are challenges and opportu...
Article
Full-text available
Fabrication of materials for current energy applications is one of the most exciting areas of contemporary materials research. Over the past few years, the oldest perovskites and their related materials stay in the frontline of this research, yielding advancements to photovoltaic, optoelectronic, and laser technologies. Previously, familiar zero-di...
Article
Full-text available
Investigating the mechanical properties of polymer nanocomposite materials has been greatly increased in the last decade. In particular, flexural strength plays a major role in resisting bending and shear loads of a composite material. Here, one dimensional (1D) tellurium nanowires (TeNWs) reinforced epoxy composites have been prepared and the flex...
Article
Metal oxide nanoparticles have been used as excellent reinforcements to enhance mechanical properties of polymers, natural composites, and ceramics. To date, a major portion of metal oxides used as nanofillers is three dimensional spherical nanoparticles. In the last decade, two-dimensional (2D) materials such as graphene have been widely investiga...
Article
Full-text available
Mercaptosuccinic acid (MSA) protected silver clusters ([email protected]) were synthesized and their stability was monitored both in an aqueous and in a toluene phase. In the former, the pH of the cluster solution was tuned between 3 and 10 using ammonium acetate buffer, and the cluster stability was tested. The clusters were unstable at all measur...
Article
Atomically precise zero dimensional (0D) silver quantum clusters (QCs) protected by thiolates have emerged as a new class of nanomaterials. Because of their high luminescence and ultra-small size, they hold great promise for the fabrication of light-emitting sources in nanoscale devices. Epoxy resins are highly cross-linked polymer materials with m...
Article
Active control over the shape, composition and crystalline habit of nanocrystals is a long sought-after goal. Various methods have been shown to enable post-synthesis modification of nanoparticles, including the use of the Kirkendall effect, galvanic replacement and cation or anion exchange, all taking advantage of enhanced solid-state diffusion on...
Article
Self-assembly of inorganic nanoparticles has been used to prepare hundreds of different colloidal crystals, but almost invariably with the restriction that the particles must be densely packed. Here, we show that non–close-packed nanoparticle arrays can be fabricated through the selective removal of one of two components comprising binary nanoparti...
Article
In this work, we presented the potentiality of monodispersed 3D hierarchical α-Fe2O3 nanoflowers (α-Fe2O3) as reinforcement for epoxy polymer. α-Fe2O3 are synthesized through the thermal decomposition of iron alkoxide precursor in ethylene glycol. α-Fe2O3/epoxy nanocomposites (0.1 wt% of α-Fe2O3) show 109%, 59%, 13%, and 15% enhancement in impact (...
Article
Full-text available
Active control over the shape, composition and crystalline habit of nanocrystals is a long sought-after goal. Various methods have been shown to enable post-synthesis modification of nanoparticles, including the use of the Kirkendall effect, galvanic replacement and cation or anion exchange, all taking advantage of enhanced solid-state diffusion on...
Article
Despite the recent surge of interest in lead halide perovskite nanocrystals, there are still significant gaps in the understanding of nucleation and growth processes involved in their formation. Using CsPbX3 as a model system, we systematically study the formation mechanism of cubic CsPbX3 nanocrystals, their growth via oriented attachment into lar...
Cover Page
The Inside Cover picture illustrates the fluorescent properties of a gold nanocluster functionalized with several copies of a red-emitting merocyanine (image by Ella Marushchenko). The red fluorescence can be turned on and off reversibly by using an external stimulus. More information can be found in the Communication by T. Udayabhaskararao et al....
Article
Full-text available
The chemical behaviour of molecules can be significantly modified by confinement to volumes comparable to the dimensions of the molecules. Although such confined spaces can be found in various nanostructured materials, such as zeolites, nanoporous organic frameworks and colloidal nanocrystal assemblies, the slow diffusion of molecules in and out of...
Article
Au25 nanoclusters functionalized with a spiropyran molecular switch are synthesized via a ligand-exchange reaction at low temperature. The resulting nanoclusters are characterized by optical and NMR spectroscopies as well as by mass spectrometry. Spiropyran bound to nanoclusters isomerizes in a reversible fashion when exposed to UV and visible ligh...
Article
One dimensional (1D) tellurium nanowires (Te NWs) reinforced epoxy composites have been prepared and the mechanical properties of Te/Epoxy nanocompositeswith respect to tensile and impact properties were studied. Thelength and width of the TeNWs used to make Te NWs/Epoxy nanocompositesare 697±87 nmand 21±2.5 nm, respectively.Mechanical stirrer disp...
Article
Full-text available
The ability to guide the assembly of nanosized objects reversibly with external stimuli, in particular light, is of fundamental importance, and it contributes to the development of applications as diverse as nanofabrication and controlled drug delivery. However, all the systems described to date are based on nanoparticles (NPs) that are inherently...
Patent
Methods for the synthesis of metal quantum clusters within the framework of a porous gel matrix are described. For example, Ag25(glutathione)18 quantum clusters are synthesized in a cross-linked polyacrylamide gel matrix. The methods can be performed on large-scale and yields monodispersed metal quantum clusters.
Article
Precise control of the self-assembly of selected components within complex mixtures is a challenging goal whose realization is important for fabricating novel nanomaterials. Herein we show that by decorating the surfaces of metallic nanoparticles with differently substituted azobenzenes, it is possible to modulate the wavelength of light at which t...
Article
Full-text available
The magnetic field-induced self-assembly of inorganic nanoparticles has been studied extensively for particles having different sizes and compositions. However, relatively little attention has been devoted to how the shape and surface chemistry of magnetic nanoparticles affects their self-assembly properties. Here, we undertook a combined experimen...
Article
We report the systematic appearance of a plasmon-like optical absorption feature in silver clusters protected with 2-phenylethanethiol (PET), 4-flurothiophenol (4-FTP) and (4-(t-butyl)benzenethiol (BBS), as a function of cluster size. A wide range of clusters, namely, Ag44(4-FTP)30, Ag55(PET)31, ~Ag75(PET)40, ~Ag114(PET)46, Ag152(PET)60, ~Ag202(BBS...
Article
Reactivity of two different nanosystems of silver, namely nanoparticles and atomically precise clusters, toward 1D tellurium nanowires (NWs) was probed and compared with the reaction of silver ions. While the reaction of nanoparticles and ions led to silver telluride nanowires, a different reactivity was exhibited by clusters which resulted in silv...
Article
Luminescent AgAu alloy quantum clusters are synthesized by a simple method that utilizes the galvanic reduction of polydisperse plasmonic silver nanoparticles. The clusters are characterized by ultraviolet–visible (UV/Vis) absorption spectroscopy, photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron mic...
Patent
Full-text available
The invention relates to a method for prepg. monolayer protected, atomically precise silver clusters as antibacterial agents. The method comprises, (a) sonicating a mixt. of silver nitrate and glutathione (GSH)/mercaptosuccinic acid (MSA)/cysteine for 1 h an aq. base to obtain a soln. contg. oligomeric silver thiolate, (b) mixing the soln. contg. o...
Article
Full-text available
Clusters composed of a 32 silver atom core, protected with thiolates of glutathione (GSH) and N-(2-mercaptopropionyl)glycine (MPGH), were synthesized by a solid-state route in milligram scale. They do not exhibit surface plasmon resonance unlike their larger sized nanoparticle analogues but show molecule-like features in absorption and luminescence...
Article
Full-text available
Glutathione protected, silver clusters were synthesized within gel cavities, using sunlight. Compared to the conventional chemical reduction process, this method is cheaper and environment-friendly as it involves the use of natural resources. As-synthesized silver quantum clusters in aqueous medium shows distinct step-like behavior in its absorptio...
Article
“Catching” metals in the nonmetallic form in solution, as they grow to bulk, is one of the most exciting areas of contemporary materials research. A new kind of stabilization to catch the nonmetallic form of noble metals with small thiols has evolved as an exciting area of synthesis during the past decade. Gold clusters stay in the frontline of thi...
Article
A copper cluster protected with 2-phenylethanethiol (PET) exhibiting distinct optical features in UV/Vis spectroscopy is reported. Matrix-assisted laser desorption ionisation mass spectrometry of the cluster shows a well-defined molecular ion peak at m/z 5,800, assigned to ~Cu38(PET)25. Fragmented ions from the cluster show the expected isotope pat...
Article
Researchers reported about the systematic size evolution of an organic-soluble, atomically precise silver cluster. Evolution of precise silver cluster larger nanoparticles was observed by mass spectrometry, while the formation of nanoparticles and crystals was investigated by electron microscopy. A solid-state route was used to synthesize atomicall...
Article
We report the effect of temperature on the stability of glutathione-protected Ag25 clusters. The clusters are stable up to 50 °C. Interestingly, above this temperature, they decompose to yield Ag2S nanoparticles with an average diameter of 3 ± 1 nm, crystallizing in monoclinic acanthite polymorph. Unlike conventional methods of syntheses of Ag2S, w...
Article
We report the effect of temperature on the stability of glutathione-protected Ag 25 clusters. The clusters are stable up to 50 °C. Interestingly, above this temperature, they decompose to yield Ag 2 S nanoparticles with an average diameter of 3 ± 1 nm, crystallizing in monoclinic acanthite polymorph. Unlike conventional methods of syntheses of Ag 2...
Article
Full-text available
We describe the degradation of chlorocarbons (CCl 4 , C 6 H 5 CH 2 Cl and CHCl 3) in solution at room temperature (27 AE 4 C) by the monolayer-protected silver quantum cluster, Ag 9 MSA 7 (MSA: mercaptosuccinic acid) in the presence of isopropyl alcohol (IPA). The main degradation products were silver chloride and amorphous carbon. Benzyl chloride...
Article
We report a one-step route for the synthesis of highly luminescent and water-soluble Au18SG14 (SG- glutathione in thiolate form) in nearly pure form using a slow reduction process. The cluster shows step-like behavior in its absorption profile. It emits red light in both aqueous and solid state under UV illumination. Quantum yield of the cluster is...
Article
Full-text available
We report the first high temperature solution state synthesis of glutathione (-SG) protected atomically precise silver clusters. Noble metal cluster synthesis from metal ions generally requires ice cold temperatures as they are extremely sensitive and high temperature routes are used only for core reduction methods, starting from nanoparticles. The...
Article
We report the first high temperature solution state synthesis of glutathione (ÀSG) protected atomically precise silver clusters. Noble metal cluster synthesis from metal ions generally requires ice cold temperatures as they are extremely sensitive and high temperature routes are used only for core reduction methods, starting from nanoparticles. The...
Article
We thank the Department of Science and Technology, Government of India for constantly supporting our research program on nanomaterials. This research was supported in part by the U.S. Department of Energy under grant number DE-FG02-05ER15657 and in part by the Department of Homeland Security’s collaborative academic research program. The work at LL...
Article
We describe the application of a recently discovered family of materials called quantum clusters, which are sub-nanometer particles composed of a few atoms with well-defined molecular formulae, exhibiting intense absorption and emission in the visible region in metal ion sensing, taking Ag(25) as an example. The changes in the optical properties of...
Article
Full-text available
A red luminescent silver cluster was synthesized in milligram quantities by the direct core reduction of the most widely studied class of large silver nanoparticles, namely silver@citrate of tens of nanometres diameter. No byproducts such as thiolates were detected, unlike in the case of typical methods of making such clusters. The route provides n...
Article
We report a joint experimental and theoretical study of two luminescent molecular quantum clusters of silver, Ag7(H2MSA)7 and Ag8(H2MSA)8 (H2MSA is the dicarboxylic acid of mercaptosuccinic acid in thiolate form). Global optimizations and property calculations are performed in the framework of density-functional theory (DFT-PBE) to search for the l...
Article
Full-text available
Silver quantum clusters (QCs) stabilized by mercaptosuccinic acid (MSA) have been synthesized at room temperature from Ag nanoparticles through an interfacial etching process. The as-synthesized red emitting QCs were coated on alumina and the supported clusters have been characterized by transmission electron microscopy (TEM), X-ray photoelectron s...
Article
Full-text available
Quantum clusters (QCs) of silver such as Ag7(H2MSA)7, Ag8(H2MSA)8 (H2MSA, mercaptosuccinic acid) were synthesized by the interfacial etching of Ag nanoparticle precursors and were loaded on metal oxide supports to prepare active catalysts. The supported clusters were characterized using high resolution transmission electron microscopy, scanning ele...
Data
Figure S5. Positive ion ESI-MS of the product obtained in 50:50 water:methanol mixture, compared with those of pure 4-np and 4-ap. Complete disappearance of the peak of 4-np is noted.
Data
Figure S9. UV-vis spectra for the reduction of 4-np as a function of time, with SiO2@Ag7,8 (A1-A3), TiO2@Ag7,8 (B1-B3), and Fe2O3 @Ag7,8 (C1-C3). 1, 2, and 3 refer to the first, second, and third cycles of reduction.
Data
Figure S2. Isobestic point in the UV-vis spectra of the reduction of 4-np at 15°C. Minor changes are attributed to the presence of particles of supported clusters in the solution.
Data
Figure S4. Reusability of supported Al2O3@Ag7,8 for the reduction of 4-np, the second cycle (A), the third cycle (B), the fourth cycle (C), and the fifth cycle (D).
Data
Figure S6. XPS survey spectra of Al2O3@Ag7,8 before reaction (black), after the first (red) and the third (green) cycles of reduction reactions.
Data
Figure S7. UV-vis spectra for the reduction of 4-np with NaBH4 in the presence of supported Ag@citrate nanoparticles.
Data
Figure S1. HRTEM image of Al2O3@Ag7,8. Black dots in (A) correspond to Ag QCs which are marked. (B) Lattice-resolved image of fused silver particles obtained after 20 min of electron beam exposure showing the (111) plane of Ag. (C) EADX spectrum of Al2O3@Ag7,8 showing the presence of Ag, corresponding to the elemental map of Al (D) and Ag (E) measu...
Data
Table 1. Rate constant for the reduction of 4-np with NaBH4 in the presence of Al2O3@Ag7,8
Data
Figure S3. (A) UV-vis spectra of the increase in concentration of 4-ap during the reduction process at 35°C (a), 25°C (b), and 15°C (c). (B) A plot of concentration versus 1/T for the formation of 4-ap.
Data
Figure S8. UV-vis spectra for the reduction of 3-na (A), 4-na (B), and 3-np (C) with NaBH4 in the presence of Al2O3@Ag7,8.
Article
A silver cluster having the composition Ag(9)(H(2)MSA)(7) (H(2)MSA = mercaptosuccinic acid) was synthesized in macroscopic quantities using a solid-state route. The clusters were purified by PAGE and characterized by UV-vis, FTIR, luminescence, and NMR spectroscopy, TEM, XPS, XRD, TG, SEM/EDAX, elemental analysis, and ESI MS. The solid-state route...
Article
chemical equation presentation Interfacial etching of silver nanoparticles and separation of the products by Polyacrylamide gel electrophoresis afforded Ag8 and Ag7 clusters with red and bluegreen fluorescence emission, respectively (see picture). The strongly temperaturedependent emission of the clusters suggests potential applications, whilst the...
Article
Full-text available
We report the synthesis of luminescent Agclusters through the interfacial etching of mercaptosuccinic acid (MSA) protected silver nanoparticles, Ag@MSA, with guanine at the water-toluene interface. The clusters exhibiting well-defined absorption emit in the near-infrared (NIR) region. Crude clusters were separated using polyacrylamide gel electroph...

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Projects (3)
Project
Ag nanoclusters synthesized through a novel technique for hydrocarbon destruction