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

  • Shibin Thundiyil, Sreekumar Kurungot And R. Nandini Devi, Synergistic effect of B site co-doping with Co and Ce in bifunctional oxygen electrocatalysis by oxygen deficient brownmillerite Ba2In2O5, Catal Today., 375, 494 - 500 (2021), DOI:10.1016/j.cattod.2020.05.046.
    Specificity in oxygen reduction and evolution reactions is pivotal in bifunctional catalysts in advanced energy devices which are expected to be active in a wide potential window and stable in both electrochemically reducing and oxidising atmospheres. State of the art noble metal catalysts for these reactions are fraught with issues whereas, metal oxides are expected to be stable in large potential window and can be tuned to have better bifunctional activity. Catalytically active metals, redox centers, oxygen vacancies etc. are some of the features of structured oxides which can be exploited in oxygen electrocatalysis. Brownmillerite family of compounds with general formula, A2B2O5 has high concentrations of ordered oxygen vacancy in a layer and can be promising bifunctional oxygen electrocatalysts, by appropriate B site doping. Ba2In2O5 is a well studied system for its oxide ion conductivity and proximity of active B sites to O vacancies provide good O adsorption sites which are catalytically active. Here, Cobalt and Cerium are co-doped in Ba2In2O5, anticipating a synergistic effect of Ce(III)/Ce(IV) redox center in ORR and Co activity in OER along with O vacancies providing adsorption sites. We have studied the structural changes associated with the doping by Rietveld refinement of the XRD patterns and correlated the structure to bifunctional oxygen electrocatalytic activity which is found to enhance on increasing the Co and Ce content.
  • Shibin Thundiyil, Sreekumar Kurungot And R. Nandini Devi, Efficient electrochemical oxygen reduction to hydrogen peroxide by transition metal doped silicate, Sr0.7Na0.3SiO3-?, ACS Appl. Mater. Interfaces., 13, 382 - 390 (2021), DOI:10.1021/acsami.0c16311.
    Electrochemical oxygen reduction in a selective two-electron pathway is an efficient method for onsite production of H2O2. State of the art noble metal-based catalysts will be prohibitive for widespread applications, and hence earth-abundant oxide-based systems are most desired. Here we report transition metal (Mn, Fe, Ni, Cu)-doped silicates, Sr0.7Na0.3SiO3??, as potential electrocatalysts for oxygen reduction to H2O2 in alkaline conditions. These novel compounds are isostructural with the parent Sr0.7Na0.3SiO3?? and crystallize in monoclinic structure with corner-shared SiO4 groups forming cyclic trimers. The presence of Na stabilizes O vacancies created on doping, and the transition metal ions provide catalytically active sites. Electrochemical parameters estimated from Tafel and Koutechy–Levich plots suggest a two-electron transfer mechanism, indicating peroxide formation. This is confirmed by the rotating ring disc electrode method, and peroxide selectivity and Faradaic efficiency are calculated to be in the range of 65–82% and 50–68%, respectively, in a potential window 0.3 to 0.6 V (vs RHE). Of all the dopants, Ni imparts the maximum selectivity and efficiency as well as highest rate of formation of H2O2 at 1.65 ?mol s–1
  • Anurag Chahande, Disha Lathigara, Asmita Prabhune And R.Nandini Devi, Red fluorescent ultra-small gold nanoclusters functionalized with signal molecules to probe specificity in quorum sensing receptors in gram-negative bacteria, Archives of Microbiology., 203, 4293 - 4301 (2021), DOI:doi.org/10.1007/s00203-021-02338-y.
  • Shunottara M Jogdand, Prachiti R Bedadur, Arun Torris, Ulhas K Kharul, V Satyam Naidu And R Nandini Devi, Tuning the selectivity of CO2 hydrogenation using ceramic hollow fiber catalytic modules, React. Chem. Eng., 6, 1655 - 1665 (2021), DOI:https://doi.org/10.1039/D1RE00076D.
  • Shunottara M Jogdand, Prachiti R Bedadur, Arun Torris, Ravi Agrawal, Ulhas K Kharul And R Nandini Devi, Addressing challenges in sealing of scalable multifiber module for O2 enrichment using LSCF membranes, Int J Appl Ceram Technol., , (2021), DOI:https://doi.org/10.1111/ijac.13967.
  • Shibin Thundiyil, C. P. Vinod, Sreekumar Kurungot And R. Nandini Devi, Role of B site ion in bifunctional oxygen electrocatalysis: A structure property correlation study on doped Ca2Fe2O5 brownmillerites, Phys Chem Chem Phys., 22, 15520 - 15527 (2020), DOI:10.1039/D0CP02391D.
    Role of B site doping with transition metal in brownmillerites, a perovskite related family of compounds, on bifunctional oxygen electrocatalysis, viz., simultaneous reduction and evolution reactions, is analysed. Ca2Fe1.9M0.1O¬5 (M= Mn, Co, Ni, Cu) is synthesised and structurally characterised by powder XRD and Rietveld refinement. Valence states of the surface B site ions are identified by X-ray photoelectron spectroscopy. Bifunctional oxygen electrochemistry is studied with RDE and RRDE techniques and correlated to the structural and electronic parameters like oxygen non-stoichiometry and B site catalytic activity. Since the widely accepted electronic descriptors like eg filling may not be sufficient for explaining bifunctional activity, B site electron donating capability as well as extent of oxygen vacancies enhancing O2 adsorption is also considered. Such structural parameters are also found to influence both ORR and OER and based on this, Ni doping is proposed as advantageous for the bifunctional activity.
  • Shibin Thundiyil, Sreekumar Kurungot And and R. Nandini Devi, Bifunctional Oxygen Reduction and Evolution Activity in Brownmillerites Ca2Fe(1–x)CoxO5, ACS Omega., 4, 31 - 38 (2019), DOI:10.1021/acsomega.8b02468.
    State-of-the-art catalysts for oxygen reduction and evolution reactions (ORR and OER), which form the basis of advanced fuel cell applications, are based on noble metals such as Pt and Ir. However, high cost and scarcity of noble metals have led to an increased demand of earth-abundant metal oxide catalysts, especially for bifunctional activity in ORR and OER. The fact that Pt and Ir or C, the cost-effective alternatives suggested, do not display satisfactory bifunctional activity has also helped in turning the interest to metal oxides which are stable under both ORR and OER conditions. Brownmillerite A2B2O5 type oxides are promising as bifunctional oxygen electrocatalysts because of intrinsic structural features, viz., oxygen vacancy and catalytic activity of the B-site transition metal. In this study, Co-doped Ca2Fe2O5 compounds are synthesized by the solid state method and structurally analyzed by Rietveld refinement of powder X-ray diffraction data. The compound Ca2Fe2O5, crystallizing in the Pcmn space group has alternative FeO4 tetrahedral and FeO6 octahedral layers. Its Co-doped analogue, Ca2Fe1.75Co0.25O5, also crystallizes in the same space group with both tetrahedral and octahedral Fe positions substituted with Co. However, Ca2FeCoO5 in the Pbcm space group shows interlayer ordering with Co-rich octahedra connected to Fe-rich tetrahedra and vice versa. Oxygen bifunctional activities of these catalysts are monitored by rotating disc electrode and rotating ring disc electrode techniques in alkaline media. A close analysis of the ORR and OER was conducted through comparison of various parameters such as onset potential, current density, halfwave potential, and other kinetic parameters, which suggests that the presence of Co in the B site aids in achieving better bifunctional activity and bulk conductivity. In addition, Co(II)/Co(III) redox systems and their comparative concentrations also play a decisive role in enhancing the activity.
  • Pavan Dongapure, Sayan Bagchi, S. Mayadevi And R. Nandini Devi, Variations in activity of Ru/TiO2 and Ru/Al2O3 catalysts for CO2 hydrogenation: An investigation by in-situ infrared spectroscopy studies, Molecular Catalysis., 482, 110700 (2019), DOI:10.1016/j.mcat.2019.110700.
    CO2 hydrogenation to methane, an important reaction strategically and also for value adding to CO2, is investigated on two different catalysts, Ru supported on alumina as well as titania to understand better low temperature activity of Ru/TiO2 catalyst. In-situ infrared studies are carried out in three different steps, viz., (i) CO2 adsorption on fully reduced catalyst (ii) reaction of these adsorbed species with gaseous H2 and (iii) under co-feed of CO2 and H2, at different temperatures. On Ru/Al2O3 catalyst, CO2 reacts with hydroxyls on the support surface to form carbonate and adsorbs reductively on metal as CO. Further reduction to formate and methyl species occurs on reaction with H. Small concentration of the reactive intermediate formyl forms only at high temperatures. Whereas, bare TiO2 itself seems capable of reductive adsorption of CO2 as formate indicating enhanced reducibility of titania based catalyst. Formyl groups are observed at low temperatures in Ru/TiO2 in step (ii), which further forms methyl and gaseous methane at much lower temperatures when compared to alumina catalyst. Highly reactive CO species loosely bound to metal-support interface observed at high temperatures, which is not present on Ru/Al2O3 catalyst also makes this catalyst superior. In comparison, linearly bound CO seen in alumina catalyst is not as reactive.
  • Kayaramkodath Chandran Ranjeesh, Leena George, Vivek Chandrakant Wakchaure, Goudappagouda And R. Nandini Devi and Sukumaran Santhosh Babu, A squaraine-linked metalloporphyrin two-dimensional polymer photocatalyst for hydrogen and oxygen evolution reactions, Chem. Commun., 55, 1627 - 1630 (2019), DOI:10.1039/C8CC09132C.
  • Subrahmanyam Sappati, Leena George, Vincent Paul Swamy And R. Nandini Devi Prasenjit Ghosh, Descriptors to Predict Dye?Sensitized Semiconductor Based Photocatalyst for Hydrogen Evolution Reaction, Chem Cat Chem., Just Published, (2019), DOI:10.1002/cctc.201901924.
  • Chamundi P. Jijil, Indrajit M. Patil, Bhalchandra Kakade And and R. Nandini Devi, Cobalt-Doped Ba2In2O5 Brownmillerites: An Efficient Electrocatalyst for Oxygen Reduction in Alkaline Medium, ACS Omega., 3, 1710 - 1717 (2018), DOI:10.1021/acsomega.7b01655.
    A series of compounds with cobalt doping in the indium site of Ba2In2O5 brownmillerites exhibited excellent oxygen reduction activity under alkaline conditions. Doping (25%) retains the brownmillerite structure with disorder in the O3 site in the two-dimensional alternate layer along the ab plane. Further substitution of cobalt in the indium site leads to the loss of a brownmillerite structure, and the compound attains a perovskite structure. Cobalt-doped samples exhibited far better oxygen reduction reaction (ORR) activity when compared to the parent Ba2In2O5 brownmillerite. Among the series of compounds, BaIn0.25Co0.75O3?? with the highest Co doping and oxygen vacancies randomly distributed in the lattice exhibited the best ORR activity. BaIn0.25Co0.75O3?? showed a 40 mV positive shift in the onset potential with better limiting current density and a nearly four-electron-transfer reduction pathway when compared to the parent Ba2In2O5 brownmillerite.
  • Leena George, Subrahmanyam Sappati, Prasenjit Ghosh And R. Nandini Devi, Sensitizing with short conjugated molecules: Multimodal anchoring on ZnO nanoparticles for enhanced electron transfer characteristics, stability and H2 evolution, Catal Today., 309, 89 - 97 (2018), DOI:1016/j.cattod.2017.09.052.
    Sensitizing semiconductors with organic dyes is usually employed to improve efficiency of semiconductors towards visible light absorption and charge transport. However, till date most of the dyes are either noble metal based with complex and expensive synthesis procedure or have a very narrow absorption band. Further the photostability of the dyes is another important issue. In this work we have studied, using a combination of photophysical and computational methods, ZnO nanoparticles sensitized with transition metal free, cheap and easy to synthesize azoquinoline dye that has been designed to have multiple chelating sites, viz., carboxylic group and hydroxyl imine group as a photocatalyst for water splitting activity. We find that the presence of multiple chelating sites facilitates dual mode of anchoring on ZnO nanoparticles, which leads to enhanced photostability and H2 generation of the composite. This is attributed to the incorporation of resonance features in the dye that increases electron transfer between ZnO and dye in contrast to the charge accumulation and photo degradation observed in non-conjugated and single site anchoring counterparts. Electron transfer from ZnO to dye under UV light and reverse in visible light could be identified experimentally. Such simple designing aspects can aid in identifying better catalysts for photocatalytic water splitting.
  • Sourik Mondal, Thattarathody Rajesh, Basab Bijayi Dhar, Markus Snellman, Junjie Li And Leonard Deepak Francis and R. Nandini Devi , Understanding alloy structure and composition in sinter-resistant AgPd@SiO2 encapsulated catalysts and their effect on catalytic properties, New J. Chem., 41, 14652 - 14658 (2017), DOI:10.1039/C7NJ03652C.
    Extent of alloying and alloy composition, crucial in determining the activity and selectivity of bimetallic catalysts, are studied in porous silica encapsulated AgPd catalysts using XRD, HRTEM and HAADF-STEM. Water dispersible ligand protected Pd ultra small clusters and Ag nanoparticles of three different sizes are used as precursors. High reactivity of Pd ultra small clusters enhances alloying of even big Ag nanoparticles to an extent. Encapsulation seems to have minimised the sintering of the resultant nanoparticles. Earlier suggestions of role of d-band positions with respect to adsorption energies holds good for AgPd system also and alloying enhances the activity. Alloy of composition Ag50Pd50 is found to be the most active with rate of the reaction enhanced two fold in this system compared to other compositions. Other factors like particle size and sinter-resistance also play important roles in enhancing the activity of these catalysts.
  • 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

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