C. N. R. Rao

Jawaharlal Nehru Centre for Advanced Scientific Research, Bengalūru, Karnataka, India

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Publications (800)2357.2 Total impact

  • Ram Kumar · K. Gopalakrishnan · Irshad Ahmad · C. N. R. Rao
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    Ram Kumar · K. Gopalakrishnan · Irshad Ahmad · C. N. R. Rao
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    ABSTRACT: Composites of boron nitride (BN) and carboxylated graphene are prepared for the first time using covalent cross-linking employing the carbodiimide reaction. The BN1–xGx (x ≈ 0.25, 0.5, and 0.75) obtained are characterized using a variety of spectroscopic techniques and thermogravimetric analysis. The composites show composition-dependent electrical resistivity, the resistivity decreasing with increase in graphene content. The composites exhibit microporosity and the x ≈ 0.75 composite especially exhibits satisfactory performance with high stability as an electrode in supercapacitors. The x ≈ 0.75 composite is also found to be a good electrocatalyst for the oxygen reduction reaction in fuel cells.
    Advanced Functional Materials 09/2015; DOI:10.1002/adfm.201502166 · 11.81 Impact Factor
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    ABSTRACT: Electrochemical generation of hydrogen by non‐precious metal electrocatalysts at a lower overpotential is a thrust area of research directed towards sustainable energy. The exorbitant costs associated with Pt based catalysts is the major bottleneck associated with the commercial scale hydrogen generation. Hence strategies for the synthesis of cost effective and stable catalysts is craving its way for prospective 'hydrogen economy'. In this report, we highlight the novel and general strategy to enhance the electrochemical activity of molybdenum disulfide (MoS 2) in the fullerene structure (IF‐). In particular, pristine (undoped) and Rhenium‐doped nanoparticles of MoS 2 with fullerene‐like structure (IF‐MoS 2) were studied and their performance as catalysts for hydoregen evolution reaction (HER) was compared to that of 2H‐MoS 2 particles (platelets). The current density of IF‐MoS 2 is higher by one order of magnitude as compared to few‐layer (FL‐) MoS 2 due to the enhanced density of edge sites. Furthermore, Re‐doping as low as 100 ppm in IF‐MoS 2 decreases the onset potential by 60‐80 mV and increases the activity by 60 times compared to FL‐MoS 2. The combined synergistic effect of Re‐doping and the IF‐structure not only changes the intrinsic nature of MoS 2 but also increases its reactivity. This strategy highlights the potential use of IF‐structure and Re‐doping in electrocatalytic hydrogen evolution using MoS 2 based catalysts.
    Dalton Transactions 08/2015; DOI:10.1039/C5DT02562A · 4.20 Impact Factor
  • Anand Roy · S. R. Lingampalli · Sujoy Saha · C. N. R. Rao
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    ABSTRACT: Hydrogen can be generated by visible light irradiation of semiconductor heterostructures of the type ZnO/Pt/CdS and TiO2/Pt/CdS. In order to understand the dependence of hydrogen generation on the properties of the nanoparticles of ZnO and TiO2, we have carried out systematic studies. For this purpose, we have studied photocatalytic hydrogen generation by ZnO(TiO2)/Cd1-xZnxS and ZnO(TiO2)/Pt/Cd1-xZnxS (x = 0.0, 0.2) heterostructures with oxide nanostructures possessing different morphologies and surface areas. In the case of TiO2/Pt/Cd0.8Zn0.2S heterostructures, the highest H2 evolution rate up to1.76 mmol h-1 g -1 were obtained with H2Ti3O7 nanotubes, with the least H2 evolution rate (0.55 mmol h-1 g -1) from TiO2 powder (Degussa P25). In the case of ZnO/Pt/CdS heterostructures, the highest H2 evolution rate (6.88 mmol h-1 g -1) were obtained from ZnO nanorods1, whereas the least H2 evolution rate (2.55 mmol h-1g-1) was obtained from ZnO nanorods3. The photocatalytic activity of heterostructures generally follows the trend in BET surface areas of the oxide nanostructures, with high surface area favoring good hydrogen evolution activity.
    Chemical Physics Letters 08/2015; DOI:10.1016/j.cplett.2015.08.005 · 1.90 Impact Factor
  • C.N.R. Rao · Urmimala Maitra
    Annual Review of Materials Research 07/2015; 45(1):29-62. DOI:10.1146/annurev-matsci-070214-021141 · 11.85 Impact Factor
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    ABSTRACT: We report high-pressure Raman-scattering studies on single-crystal ReO 3 up to 26.9 GPa at room temperature, complemented by first-principles density functional calculations to assign the modes and to develop understanding of the subtle features of the low-pressure phase transition. The pressure (P) dependence of phonon frequencies (ω) reveals three phase transitions at 0.6, 3, and 12.5 GPa with characteristic splitting and changes in the slope of ω(P). Our first-principles theoretical analysis confirms the role of the rotational modes of ReO 6 , M 3 , to the lowest pressure structural transition, and shows that the transition from the P m3m to the I m3 structure is a weak first-order transition, originating from the strong anharmonic coupling of the M 3 modes with the acoustic modes (strain).
    Physical Review B 06/2015; 91(22). DOI:10.1103/PhysRevB.91.224308 · 3.74 Impact Factor
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    ABSTRACT: Using first-principles local and hybrid density functional theoretical calculations, a thickness-dependent electronic structure of layered GaS is determined, and it is shown that 2D GaS has an electronic structure with valence and conduction bands that straddle the redox potentials of hydrogen evolution reaction and oxygen evolution reaction up to a critical thickness (<5.5 nm). Here, simulations of adsorption of H2 O on nanoscale GaS reveal that localized electronic states at its edges appear in the gap and strengthen the interaction with H2 O, further activating the surface atomic sites. It is thus predicted that GaS synthesized with a controlled thickness and preferred edges may be an efficient catalyst for photocatalytic splitting of water. Experiments that verify some of the predictions in this study are presented, and it is shown that GaS is effective in absorption of light and evolution of H2 (887 μmol h(-1) g(-1) ) in the presence of aqueous solution of hydrazine (1% v/v). This study should open up the use of nanoscale GaS in conversion of solar energy into environment-friendly chemical energy in the form of hydrogen. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Small 06/2015; 11(36). DOI:10.1002/smll.201501077 · 8.37 Impact Factor
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    ABSTRACT: Unlike cation substitution, anion substitution in inorganic materials such as metal oxides and sulfides would be expected to bring about major changes in the electronic structure and properties. In order to explore this important aspect, we have carried out first-principles DFT calculations to determine the effects of substitution of P and Cl on the properties of CdS and ZnS in hexagonal and cubic structures and show that a sub-band of the trivalent phosphorus with strong bonding with the cation appears in the gap just above the valence band, causing a reduction in the gap and enhancement of dielectric properties. Experimentally, it has been possible to substitute P and Cl in hexagonal CdS and ZnS. The doping reduces the band gap significantly as predicted by theory. A similar decrease in the band gap is observed in N and F co-substituted in cubic ZnS. Such anionic substitution helps to improve hydrogen evolution from CdS semiconductor structures and may give rise to other applications as well. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition in English 04/2015; DOI:10.1002/anie.201501532R1 · 13.45 Impact Factor
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    Sunita Dey · B. S. Naidu · A. Govindaraj · C. N. R. Rao
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    ABSTRACT: Perovskite oxides of the composition La1-xCaxMnO3 (LCM) have been investigated for the thermochemical splitting of H2O and CO2 to produce H2 and CO respectively. The study was carried out in comparison with La1-xSrxMnO3, CeO2 and other oxides. The LCM system exhibits superior characteristics in high-temperature evolution of oxygen, and in reducing CO2 to CO and H2O to H2. The best results are found with La0.5Ca0.5MnO3 whose performance is noteworthy compared to that of other oxides including ceria. The orthorhombic structure of LCM seems to be a crucial factor.
    Physical Chemistry Chemical Physics 11/2014; 17(1). DOI:10.1039/C4CP04578E · 4.49 Impact Factor
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    ABSTRACT: The presence of nitrogen heteroatoms within the lattice of reduced graphene oxide sheets induces a remarkable increase in the thermal stability against oxidation by air. This phenomenon is represented by a nitrogen-doped (blue spheres) graphene sheet withstanding a flame. For more details, see the Communication by C. N. R. Rao, G. Tobias et al. on page 11999 ff.
    Chemistry - A European Journal 09/2014; 20(38):12324-12324. DOI:10.1002/chem.201490161 · 5.73 Impact Factor
  • S. R. Lingampalli · Anand Roy · M. Ikram · C. N. R. Rao
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    ABSTRACT: ZnO/NiO/Cd1-xZnxS (x= 0.0, 0.2) heterostructures have been prepared by a simple solution-based procedure using ZnO/NiO heterostructures prepared by different methods. We obtain good hydrogen evolution activity only with ZnO/NiO heterostructures and not with Zn1-yNiyO solid solutions. The hydrogen evolution activities of ZnO/NiO/CdS and ZnO/NiO/Cd1-xZnxS are 2.2 and 8.2 mmol/h/g respectively with apparent quantum yields of 2.3 and 14% under visible-light irradiation. These values of activity are comparable or superior to those obtained with ZnO/Pt/ Cd1-xZnxS and ZnO/Au/ Cd1-xZnxS heterostructures. With UV-visible irradiation, the activity found with ZnO/NiO/Cd1-xZnxS is 14-17 mmol/h/g with an apparent quantum yield in the range of 12-15%.
    Chemical Physics Letters 07/2014; 610. DOI:10.1016/j.cplett.2014.07.052 · 1.90 Impact Factor
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    ABSTRACT: Metal–organic frameworks (MOFs) and boron nitride both possess novel properties, the former associated with microporosity and the latter with good mechanical properties. We have synthesized composites of the imidazolate based MOF, ZIF-8, and few-layer BN in order to see whether we can incorporate the properties of both these materials in the composites. The composites so prepared between BN nanosheets and ZIF-8 have compositions ZIF–1BN, ZIF–2BN, ZIF–3BN and ZIF–4BN. The composites have been characterized by PXRD, TGA, XPS, electron microscopy, IR, Raman and solid state NMR spectroscopy. The composites possess good surface areas, the actual value decreasing only slightly with the increase in the BN content. The CO2 uptake remains nearly the same in the composites as in the parent ZIF-8. More importantly, the addition of BN markedly improves the mechanical properties of ZIF-8, a feature that is much desired in MOFs. Observation of microporous features along with improved mechanical properties in a MOF is indeed noteworthy. Such manipulation of properties can be profitably exploited in practical applications.
    07/2014; 1(5). DOI:10.1039/C4MH00065J
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    Rana Saha · A. Sundaresan · C. N. R. Rao
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    ABSTRACT: A few oxides such as YMnO3, TbMnO3, YMn2O5 and BiFeO3 constituted the small family of well-characterized multiferroics until recently, but this area of research has been enlarged significantly due to the advent of a novel class of oxides exhibiting interesting multiferroic and magnetoelectric properties arising from magnetically induced ferroelectricity. Interestingly, these materials are simple transition metal oxides, most of them possessing the perovskite structure. In this review article, we present the significant features of multiferroic and magnetoelectric ferrites and chromites which owe their ferroelectricity to magnetic interactions. Some of the important systems discussed are BiFeO3 whose properties are affected by magnetic and electric fields, rare-earth orthoferrites LnFeO(3) (Ln = Dy, Gd and Sm) and rare-earth orthochromites LnCrO(3), where exchange-striction plays a significant role. Perovskite oxides of the type Y(A(1-x)B(x))O-3 (A, B = Fe, Cr, Mn) exhibit multiferroic properties, although the existence of these properties in YFeO3 and YCrO3 is in doubt. Such oxides with a non-magnetic rare-earth cation at the A site and two transition metal ions in the B-site permit tuning the transition temperatures by varying the B site ions and their relative proportions or the Ln ion. Multiferroic properties of simple ferrites such as Al(Ga)FeO3 where cation disorder appears to play a role are also discussed. Problems and challenges in this area of research are indicated.
    ChemInform 07/2014; 45(27). DOI:10.1002/chin.201427231
  • Achutharao Govindaraj · C.N.R. Rao
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    ABSTRACT: Graphene can be doped with boron and nitrogen as well as with other heteroatoms, B2H6 is generally used as the boron source, while NH3 or pyridine is employed as the nitrogen source for doping graphene by chemical vapor deposition and arc-dischrge techniques. Urea as a nitrogen source is also found to be very effective. Substitutional doping of graphene with boron and nitrogen brings about significant changes in their electronic structure and properties. Doping with boron and nitrogen causes marked changes in the Raman spectra of the carbon nanostructures. Such doping not only results in desirable properties but also allows manipulation of properties for specific purposes. In this chapter, we present the synthesis, characterization, and properties of graphene doped with boron, nitrogen, and other elements and also discuss their important applications.
    Functionalization of Graphene, 03/2014: pages 283-358; , ISBN: 9783527335510
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    ABSTRACT: Homogeneous graphene-MOF composites based on a 2D pillared-bilayer MOF (Cd-PBM), {[Cd4(azpy)2(pyrdc)4(H2O)2]·9H2O}n (azpy = 4,4'-azopyridine, pyrdc = pyridine-2,3-dicarboxylate), have been synthesized, using both graphene oxide (GO) and benzoic acid functionalized graphene (BFG). The composites GO@Cd-PBM and BFG@Cd-PBM demonstrate growth of the 2D nano-sheets of MOF on the graphene surface. While the pristine MOF, Cd-PBM shows selective CO2 uptake with a single-step type-I adsorption profile, the composites show stepwise CO2 uptake with a large hysteresis. With H2O and MeOH, on the other hand, the composites show a single-step adsorption unlike the parent MOF.
    Dalton Transactions 03/2014; 43(20). DOI:10.1039/c3dt53133c · 4.20 Impact Factor
  • Kota Moses · Vankayala Kiran · S Sampath · C N R Rao
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    ABSTRACT: The present study demonstrates the use of few-layer borocarbonitride nanosheets synthesized by a simple method as non-platinum cathode catalysts for the oxygen reduction reaction (ORR) in alkaline medium. Composition-dependent ORR activity is observed and the best performance was found when the composition was carbon-rich. Mechanistic aspects reveal that ORR follows the 4 e(-) pathway with kinetic parameters comparable to those of the commercial Pt/C catalyst. Excellent methanol tolerance is observed with the BCN nanosheets unlike with Pt/C.
    Chemistry - An Asian Journal 03/2014; 9(3). DOI:10.1002/asia.201301471 · 4.59 Impact Factor
  • Urmimala Maitra · SR Lingampalli · C. N. R. Rao
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    ABSTRACT: It is no exaggeration to state that the energy crisis is the most serious challenge that we face today. Among the strategies to gain access to reliable, renewable energy, the use of solar energy has clearly emerged as the most viable option. A promising direction in this context is artificial photosynthesis. In this article, we briefly describe the essential features of artificial photosynthesis in comparison with natural photosynthesis and point out the modest success that we have had in splitting water to produce oxygen and hydrogen, specially the latter.
    Current science 01/2014; 106(4):518-527. · 0.93 Impact Factor
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    ABSTRACT: Two sorts of MoS2 : A single-layer, metallic form of MoS2 (1T-MoS2 ) and a nanocomposite of a second form of MoS2 (few-layer 2H-MoS2 ) with heavily nitrogenated reduced graphene oxide (NRGO; N content ca. 15 %) show outstanding performance in the production of H2 under visible-light illumination.
    Angewandte Chemie International Edition 12/2013; 52(49). DOI:10.1002/anie.201306918 · 11.26 Impact Factor

Publication Stats

18k Citations
2,357.20 Total Impact Points


  • 1992–2014
    • Jawaharlal Nehru Centre for Advanced Scientific Research
      • • International Centre for Materials Science (ICMS)
      • • Chemistry and Physics of Materials Unit
      • • New Chemistry Unit
      Bengalūru, Karnataka, India
  • 2011
    • Council of Scientific and Industrial Research (CSIR), New Delhi
      New Dilli, NCT, India
  • 1996–2010
    • University of California, Santa Barbara
      • Materials Research Laboratory
      Santa Barbara, California, United States
  • 2008
    • Uppsala University
      • Department of Engineering Sciences
      Uppsala, Uppsala, Sweden
  • 1984–2007
    • University of Cambridge
      • • Department of Materials Science and Metallurgy
      • • Faculty of Physics and Chemistry
      Cambridge, ENG, United Kingdom
  • 1989–2005
    • Bhabha Atomic Research Centre
      Mumbai, Mahārāshtra, India
  • 1981–2003
    • Tata Institute of Fundamental Research
      • Department of Condensed Matter Physics and Materials Science
      Mumbai, Maharashtra, India
    • Indian Institute of Science
      • Department of Solid State and Structural Chemistry Unit
      Bengalūru, Karnataka, India
  • 1975–2001
    • University of Oxford
      • Inorganic Chemistry Laboratory
      Oxford, ENG, United Kingdom
  • 2000
    • National Physical Laboratory - India
      Old Delhi, NCT, India
  • 1995
    • University of Birmingham
      Birmingham, England, United Kingdom
    • Government of Karnataka, India
      Bengalūru, Karnataka, India
    • University of Wales
      • Department of Chemistry
      Cardiff, Wales, United Kingdom
  • 1994–1995
    • CSIR Structural Engineering Research Centre
      Chennai, Tamil Nadu, India
    • Gakushuin University
      • Department of Physics
      Edo, Tōkyō, Japan
  • 1993
    • University of Toulouse
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 1987
    • Indian Institute of Management & Research
      Jeypore, Rajasthan, India
  • 1977–1987
    • Uttar Pradesh Textile Technology Institute
      Cawnpore, Uttar Pradesh, India
  • 1983
    • Solid State Scientific Corporation
      Hollis, New Hampshire, United States
  • 1966–1976
    • Indian Institute of Technology Kanpur
      • Department of Chemistry
      Cawnpore, Uttar Pradesh, India
  • 1959–1968
    • Purdue University
      • Department of Chemistry
      West Lafayette, Indiana, United States