R. Nandini Devi

R. Nandini Devi

Catalysis Division

About Me

We are developing novel methods of synthesizing noble metal clusters and nanoparticles encapsulated in oxides endowing them with enhanced properties useful in bioimaging and catalysis. We are also developing structured oxides like perovskites as sinter-resistant catalysts in Water Gas Shift Reaction in H2 generation for fuel cells. New disordered structured oxides capable of separating O2 and N2 are also focused on as well as novel structured and composite materials for solar energy harvesting focusing on spatial separation.

Professional Experience

  • Education

    • PhD 2000, Department of Chemistry, Indian Institute of Technology Madras, Chennai, India
    • M. Sc. 1994, Department of Chemistry, Indian Institute of Technology Madras, Chennai, India
  • Research Associate, School of Chemistry, Syracuse University, USA (with Prof. J. A. Zubieta)
  • Postdoctoral Research Associate, School of Chemistry, University of St.Andrews, UK (with Dr. P. A. Wright)
  • Postdoctoral Research Fellow, Centre of the Theory and Application of Catalysis, School of Chemistry and Chemical Engineering, Queen’s University Belfast, UK (with Prof. R. Burch and Dr. Paul Collier, Johnson Matthey plc, UK)

Selected Publications

  • Soumya B. Narendranath, Saranya V. Thekkeparambil, Leena George, Shibin Thundiyil And R. Nandini Devi, Photocatalytic H2 evolution from water–methanol mixtures on InGaO3(ZnO)m with an anisotropic layered structure modified with CuO and NiO cocatalysts, J. Mol. Cat. A., 415, 82 - 88 (2016), DOI:10.1016/j.molcata.2016.01.018.
    InGaO3(ZnO)m series of oxides is found to be active for photocatalytic H2 evolution from water–methanol mixtures. The structure of this series is highly anisotropic with InO6 octahedral layers sandwiching Ga/ZnOn polyhedra. The structural anisotropy in which the conducting layer is spatially separated from the charge generation sites may help in suppressing charge recombination and consequently enhance catalytic activity. The band gaps of the series obtained from absorption spectra are above 3.6 eV and hence they are not active under visible light irradiation. H2 evolution is considerably enhanced under UV light on employing NiO as cocatalyst due to facile electron transfer from InGaO3(ZnO)m to NiO. However, when CuO is used as cocatalyst, visible light activity could be brought out. Due to the very low band gap of CuO, it can act as a sensitizer absorbing in visible light. The band positions become conducive for H2 evolution due to band alignments consequent to electron accumulation in CuO conduction band.
  • Leena George, Athira K. Kunhikannan, Rajith Illathvalappil, Divya Ottoor And Sreekumar Kurungot and R. Nandini Devi, Understanding the electron transfer process in ZnO–naphthol azobenzoic acid composites from photophysical characterisation, Phys. Chem. Chem. Phys., 18, 22179 - 22187 (2016), DOI:10.1039/C6CP02908F.
    Semiconductor nanoparticles surface modified with organic molecules capable of visible light absorption and effectively transferring the electrons to the catalytic sites have the potential to be good photocatalysts. ZnO nanoparticles of size ?3 nm are grafted with two azonaphthols, one conjugated and the other non-conjugated. The photophysical properties of modified ZnO indicate an effective electron transfer from the conjugated azonaphthol to ZnO but not in the case of the non-conjugated molecule. It is also observed from lifetime studies that the conjugated molecule stabilises the defect sites on ZnO nanoparticles. It is possible that excited electrons from the conjugated molecule are transferred to specific defect sites in ZnO. This apparently does not occur in the non-conjugated molecule, bringing to focus the importance of the photophysical characteristics of organic modifiers in designing visible light active photocatalysts.
  • Chamundi P Jijil, Moorthi Lokanathan, Sundaresan Chithiravel, Chandrani Nayak, Dibyendu Bhattacharyya, Shambhu Nath Jha, Peram Delli Babu, Bhalchandra Kakade And and R. Nandini Devi, N Doping in Oxygen Deficient Ca2Fe2O5: A Strategy for Efficient Oxygen Reduction Oxide Catalysts, ACS Applied Materials and Interfaces., Just Accepted Manuscript, (2016), DOI:10.1021/acsami.6b11718.
    Oxygen reduction reaction is increasingly being studied in oxide systems due to advantages ranging from cost effectiveness to desirable kinetics. Oxygen deficient oxides like brownmillerites are known to enhance ORR activity by providing oxygen adsorption sites. In parallel, N and Fe doping in C materials and consequent presence of catalytically active complex species like C-Fe-N is also suggested to be good strategies for designing ORR active catalysts. A combination of these features in a N doped Fe containing brownmillerite can be envisaged to present synergistic effects to improve the activity. This is conceptualized in this report through enhanced activity of N doped Ca2Fe2O5 brownmillerite when compared to its oxide parents. N doping is proved using neutron diffraction, UV-vis spectroscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. Electrical conductivity is also found to be enhanced by N doping which influences the activity. Electrochemical characterizations using cyclic voltammetry, rotating disc electrode and rotating ring disk electrode indicates an improved oxygen reduction activity in N-doped brownmillerite with a 10 mV positive shift in the onset potential. RRDE measurements show that both the compound exhibit 4-electron reduction pathways with lower H2O2 production in N-doped system also N-doped sample exhibited better stability. The observations will enable better designing of ORR catalysts which are stable and cost effective.
  • Chamundi P Jijil , Siddheshwar N. Bhange , Sreekumar Kurungot And and R. Nandini Devi, Effect of B site coordination environment in the ORR activity in disordered brownmillerites Ba2In2-xCexO5+?, ACS Appl. Mater. Interfaces., Just Accepted Manusript, (2015), DOI:10.1021/am5087837.
    Ba2In2O5 brownmillerites in which In site is progressively doped with Ce exhibit excellent oxygen reduction activity under alkaline conditions. Ce doping leads to structural changes advantageous for the reaction. 25% doping retains the ordered structure of brownmillerite with alternate layers of tetrahedra and octahedra whereas further increase in Ce concentration creates disorder. Structures with disordered oxygen atoms/vacancies are found to be better ORR catalysts probably aided by isotropic ionic conduction and Ba2In0.5Ce1.5O5+? is the most active. This enhanced activity is correlated to the more symmetric Ce site coordination environment in this compound. Stoichiometric perovskite BaCeO3 with the highest concentration of Ce shows very poor activity emphasizing the importance of oxygen vacancies, which facilitate O2 adsorption, in tandem with catalytic sites in oxygen reduction reactions.
  • Leena George, Subrahmanyam Sappati, Prasenjit Ghosh And and R. Nandini Devi, Surface Site Modulations by Conjugated Organic Molecules to Enhance Visible Light Activity of ZnO Nanostructures in Photocatalytic Water Splitting, J. Phys. Chem. C., 119, 3060 - 3067 (2015), DOI:10.1021/jp511996z.
    Surface modification of ZnO nanoparticles is identified as a method of modulating surface sites advantageously. ZnO nanoparticles of two different sizes are surface modified with a conjugated organic moiety to enable electron conduction and transfer. Enhanced H2 evolution from water methanol mixtures was observed in the composite systems compared to pristine ZnO under visible light irradiation without any cocatalyst. The system is also marginally active in water splitting in pure water without any sacrificial agents. Photophysical characterisation indicates that even though reducing size into nanoregime affects the band gap detrimentally, modifications by simple conjugated organic molecules assist in enhanced visible light activity. The experimental observations are corroborated with computational studies, which also point to a localisation of valence band maximum of the interface on the organic moiety and conduction band minimum on ZnO.
  • Soumya B. Narendranath, Ashok Kumar Yadav, Dibyendu Bhattacharyya, Shambu Nath Jha And and R. Nandini Devi, Photocatalytic H2 Evolution from Water?Methanol System by Anisotropic InFeO3(ZnO)m Oxides without Cocatalyst in Visible Light, ACS Applied Materials and Interfaces., 6, 12321 - 12327 (2014), DOI:dx.doi.org/10.1021/am501976z.
  • Soumya B. Narendranath, Ashok Kumar Yadav, T.G. Ajithkumar, Dibyendu Bhattacharyya, Shambhu Nath Jha, Krishna K. Dey, Thirumalaiswamy Raja And R. Nandini Devi , Investigations into variations in local cationic environment in layered oxide series InGaO3(ZnO)m (m = 1-4), Dalton Transactions., 43 (5), 2120 - 2126 (2014).
  • Anupam Samanta And Thattarathody Rajesh and R. Nandini Devi, Confined space synthesis of fully alloyed and sinter resistant AuPd nanoparticles encapsulated in porous silica, Journal of Materials Chemistry A., 2, 4398 - 4405 (2014), DOI:DOI:10.1039/C3TA15194H.
  • Vishal M. Dhavale, Sachin S. Gaikwad, Leena George And R. Nandini Devi and Sreekumar Kurungot, Nitrogen-doped graphene interpenetrated 3D Ni-nanocages: efficient and stable water-to-dioxygen electrocatalysts, Nanoscale., 6, 13179 - 13187 (2014), DOI:10.1039/C4NR03578J.
  • Thattarathody Rajesh and R. Nandini Devi , Role of Oxygen Vacancies in Water Gas Shift Reaction: Activity Study on BaCe0.98–xYxPt0.02O3?? Perovskites, The Journal Of Physical Chemistry C., 118, 20867 - 20874 (2014), DOI:10.1021/jp503922x.
  • Thattarathody Rajesh And R. Nandini Devi, Resistance to Ionic Pt Insertion in Oxygen Excess LaMnO3 Perovskite Lattices and Its Effect in Water Gas Shift Reaction, Journal of Molecular Catalysis A: Chemical., 395, 534 - 542 (2014), DOI:10.1016/j.molcata.2014.08.042.
    Pt doped and impregnated LaMnO3 perovskites are synthesized at different temperatures and Pt and Mn states are compared in an attempt to get insight into extent of lattice incorporation of Pt in perovskite. Various characterization studies indicate that oxygen excess system like LaMnO3 presents substantial resistance to B site doping with Pt. This behavior is different from other oxygen deficient perovskites like LaCoO3 and LaFeO3 in which lattice incorporation stabilizes the active species against sintering. Water gas shift reaction was used as a probe reaction to understand the effect of this difference in the activity. In case of LaMnO3, failure in lattice substitution leads to sintering and deactivation at high synthesis temperatures (?700 °C) in both impregnated and doped samples. In doped samples, however, a strong interaction of Pt species with a persistent amorphous phase prevents sintering at lower synthesis temperature thereby enhancing the activity when compared to impregnated sample. The study reveals a possible mechanism in which only Pt(0) species is active with perovskite playing a minimal role in this system due to the resistance to lattice incorporation.
  • Thattarathody Rajesh, Anuj Upadhyay, Anil K. Sinha, Sudip K. Deb And R. Nandini Devi, Effect of Pt incorporation in LaBO3 (B = Mn, Fe, Co) perovskites on Water Gas Shift activity, Journal of Molecular Catalysis A: Chemical., 395, 506 - 513 (2014), DOI:10.1016/j.molcata.2014.09.015.
    Pt incorporated perovskites LaBO3 (B = Mn, Co, Fe) were synthesised and characterised to understand the charge state of Pt in these materials. At the temperature range used in this study, Pt could be stabilised in ionic form in Co and Fe perovskites but not in LaMnO3. Consequent to incorporation of Pt in +2 and +4 oxidation states, reduction in B site ion charge state occurred, enhancing oxygen vacancies. Pt doped Co and Fe perovskites showed high activity for CO conversion under water gas shift conditions but the activity characteristics were found to be different for the two catalysts; LaCo1?xPtxO3?? showed methanation whereas the Fe counterpart was active in water gas shift reaction. It was also observed that methanation could be decreased and water gas shift enhanced in case of Pt doped Co perovskite when compared to Pt impregnated perovskite or mixed oxides.
  • Sourik Mondal, Anupam Samanta, Basab B. Dhar And R. Nandini Devi, Encapsulation of ultra small metal clusters in silica: Evolution of the concept of nanoreactors and the case of Ag–Pd@SiO2 alloy catalyst, Catalysis Today., , (2014), DOI:10.1016/j.cattod.2014.11.006.
    The concept of encapsulation of ultra small clusters within silica evolved as a means to address the sintering of active metal nanoparticles and subsequent deactivation observed in supported noble metal catalysts. It is hypothesised that sintering, which mainly occurs due to mobility of metal species on the support surfaces, can be minimised if the growth and movement of metal nanoparticles are constrained. First, nanoparticles are isolated inside 1D channels in 2D mesoporous compounds and the idea develops to complete encapsulation of thiol protected ultra small nanoclusters in silica spheres. Sintering is better controlled in the latter due to the confined space for growth of nanoparticles. Access of reactant molecules to the active metal surfaces also is ensured by porosity created in the silica matrix forming the basis of the concept of nanoreactors. In this paper, we elaborate on the evolution of this concept from our earlier work on highly sinter resistant silica encapsulated Au, Pd and Au–Pd alloys to the present system of Ag–Pd alloy encapsulated in silica. Silver, with the lowest Tammann temperature among noble metals, is highly prone to sintering which is adequately controlled by alloying with Pd as well as encapsulation in silica. Its enhanced activity in paranitrophenol reduction in comparison with pure metals indicates the advantageous effect of alloying.
  • Thattarathody Rajesh and R. Nandini Devi, Pt States in BaCe0.98Pt0.02O3?? During Start Up and Shut Down Operations Under Different Conditions: Stability and Activity of Ionic Pt in Water Gas Shift Reaction, Catalysis Letters., 144, 2227 - 2232 (2014), DOI:10.1007/s10562-014-1378-2.
    Stability of Pt species in doped BaCeO3 perovskites under Water gas shift reaction conditions is studied using X-ray absorption spectroscopy and in situ powder X-ray diffraction. The catalyst BaCe0.98Pt0.02O3–? has Pt in +2 oxidation state and is found to be stable in the ionic form under reaction conditions as well as under various highly reducing shut down and start up conditions. In-situ XRD under Water Gas shift reaction conditions also reveals the Pt ions to be highly stabilized in lattice and no egress is observed.
  • Anupam Samanta And R. Nandini Devi, Pd ultra small clusters as precursors for silica encapsulated Pd nanoreactors: highly sinter resistant catalysts, ChemCatChem., 5, 1911 - 1916 (2013).
  • Ruchira Mukherji, Anupam Samanta, Rajith Illathvalappil, Somak Chowdhury, Asmita Prabhune And R. Nandini Devi, Selective imaging of quorum sensing receptors in bacteria using fluorescent Au nanocluster probes surface functionalised with signal molecules, ACS Applied Materials and Interfaces., 5 (24), 13076 - 13081 (2013), DOI:10.1021/am404093m.
  • Chamundi Jijil, Sreekuttan Unni, Kurungot Sreekumar And R. Nandini Devi, Disordered brownmillerite Ba2InCeO5+ with enhanced oxygen reduction activity, Chemistry of Materials., 24 (14), 2823 - 2828 (2012).
  • Thattarathody Rajesh, Anakot K. Rajarajan, Chinnakonda S. Gopinath And R. Nandini Devi, Evidence of Cationic Pt Active for Water Gas Shift Reaction: Pt-Doped BaCeO3 Perovskite, Journal of Physical Chemistry C., 116 (17), 9526 - 9532 (2012).
  • Atul K. Prashar, Robert P. Hodgkins And Rajiv Kumar and R. Nandini Devi , In situ synthesis of Pt nanoparticles in SBA-15 by encapsulating in modified template micelles: size restricted growth within the mesochannels, Journal of Materials Chemistry., 18, 1765 - 1770 (2008), DOI:10.1039/B717991J.

Research Interest

  • Materials Chemistry including Nanomaterials
  • Fuel Cell Research
  • Heterogeneous Catalysis
  • Centre of Excellence: Solar Energy
  • Catalysis & New Methods

Contact Details

Dr. R. Nandini Devi


Scientist
Office: #289, Main Building
National Chemical Laboratory
Dr. Homi Bhabha Road
Pune 411008, India
Phone +91 20 2590 2271
Fax +91 20 2590 2633
Email: nr.devi@ncl.res.in

url: www.nandinidevi.info