Parthasarathi Bera

Bio: Parthasarathi Bera is an academic researcher from National Aerospace Laboratories. The author has contributed to research in topics: X-ray photoelectron spectroscopy & Catalysis. The author has an hindex of 39, co-authored 136 publications receiving 5329 citations. Previous affiliations of Parthasarathi Bera include Spanish National Research Council & Indian Institute of Science.

Ionic Dispersion of Pt and Pd on CeO2 by Combustion Method: Effect of Metal–Ceria Interaction on Catalytic Activities for NO Reduction and CO and Hydrocarbon Oxidation

Abstract: Ceria-supported Pt and Pd catalysts have been synthesized by the combustion method. The catalysts are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Pt and Pd metals are ionically dispersed on the CeO2 surface of crystallite sizes in the range of 15-20 nm. In 1% Pt/CeO2 Pt is found to be in the +2 and +4 oxidation states whereas Pd is in the +2 state in 1% Pd/CeO2. Catalytic activities for NO reduction by CO, NH3, CH4, and C3H8 and CO, CH4, and C3H8 oxidation by O-2 have been investigated over all these catalysts using the temperature-programmed reaction technique. The results are compared with Pt and Pd metals dispersed on alpha -Al2O3 support prepared by the combustion technique. Both oxidation and reduction reactions occur at much lower temperatures over M/CeO2 compared to those over M/Al2O3 (M = Pt, Pd). The rate and turnover frequency of NO + CO and CO + O-2 reactions over M/CeO2 are higher than those over M/Al2O3. The observed enhanced catalytic activity of M/CeO2 has been attributed to the ionic dispersion of Pt and Pd on CeO2 leading to a strong metal-ceria interaction in the form of solid solution, Ce1-xMxO2-(4-n)x/2, having linkages of the type -O2--Ce4+-O2--Mn+-O2--(n=2, 4) on the CeO2 surface

Formation of Ce1-xPdxO2-δ solid solution in combustion-synthesized Pd/CeO2 catalyst: XRD, XPS, and EXAFS investigation

Abstract: Pd/CeO2 (1 at. %) prepared by the solution-combustion method shows a higher catalytic activity for CO oxidation and NO reduction than Pd metal, PdO, and Pd dispersed over CeO2 by the conventional method. To understand the higher catalytic properties, the structure of 1 at. % Pd/CeO2 catalyst material has been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. The diffraction lines corresponding to Pd or PdO are not observed in the high-resolution XRD pattern of 1 at. % Pd/CeO2. The structure of 1 at. % Pd/CeO2 could be refined for the composition of Ce0.99Pd0.01O1.90 in the fluorite structure with 5% oxide ion vacancy. Pd(3d) peaks in the XPS in I at. % Pd/CeO2 are shifted by 3 eV indicating that Pd is in a highly ionic +2 state. EXAFS studies show the average coordination number of 3 around Pd2+ ion in the first shell of 1 at. % Pd/CeO2 at a distance of 2.02 Angstrom, instead of 4 as in PdO. The second shell at 2.72 Angstrom is due to Pd-Pd correlation which is larger than 2.69 Angstrom in PdO. The third shell at 3.31 Angstrom having 7 coordination is absent either in Pd metal or PdO, which can be attributed to -Pd2+-Ce4+- correlation. Thus, 1 at. % Pd/CeO2 forms the Ce1-xPdxO2-delta type of solid solution having -Pd2+-O-2-Ce4+- kinds of linkages.

Ionic dispersion of Pt over CeO2 by the combustion method: Structural investigation by XRD, TEM, XPS, and EXAFS

Abstract: The structure and chemical nature of Pt in combustion-synthesized $Pt/CeO_2$ catalysts have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and temperature-programmed reaction (TPR) Catalytic oxidation of CO over $Pt/CeO_2$ is correlated with its structure High-resolution XRD studies show that the structure could be refined for the composition of $Ce_1_-_xPt_xO_2_-_\delta $ in the fluorite structure with 6% oxide ion vacancy TEM images show very few Pt particles on the $CeO_2$ crystallite surface in as-prepared samples and a decrease in the density of Pt metal particles is observed on heating XPS studies demonstrate that Pt is dispersed mostly in +2(72%) and +4(21%) oxidation states on $CeO_2$, whereas only 7% is present as Pt metal particles On heat treatment, $Pt^2^+$ species increase at the cost of $Pt^4^+$ ions EXAFS studies show the average coordination number of 13 around the platinum ion in the first shell of 1% $Pt/CeO_2$ at a distance of 198 A, indicating oxide ion vacancy around the platinum ion On heating, the average oxygen coordination of Pt and oxygen increases to 23 The second shell at 297 A is due to Pt-Pt coordination, which is absent in $PtO_2$ and PtO The third shell at 328 A is not observed either in Pt metal or any of the platinum oxides, which could be attributed to $Pt^2^+-Ce^4^+$ correlation Thus, $Pt/CeO_2$ forms a $Ce_1_-_xPt_xO_2_-_\delta $ type of solid solution having $-0-Pt^2^+-O-Ce^4^+-$ kinds of linkages

Structural Investigation of Combustion Synthesized Cu/CeO2 Catalysts by EXAFS and Other Physical Techniques: Formation of a Ce1-xCuxO2-δ Solid Solution

Abstract: The structure and chemical environment of Cu in Cu/CeO2 catalysts synthesized by the solution combustion method have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and extended X-ray fine structure (EXAFS) spectroscopy. High-resolution XRD studies of 3 and 5 atom % Cu/CeO2 do not show CuO lines in their respective patterns. The structure could be refined for the composition Ce1-xCuxO2-δ (x = 0.03 and 0.05; δ ∼ 0.13 and 0.16) in the fluorite structure with 5−8% oxide ion vacancy. High-resolution TEM did not show CuO particles in 5 atom % Cu/CeO2. EPR as well as XPS studies confirm the presence of Cu2+ species in the CeO2 matrix. Redox potentials of Cu species in the CeO2 matrix are lower than those in CuO. EXAFS investigations of these catalysts show an average coordination number of 3 around the Cu2+ ion in the first shell at a distance of 1.96 A, indi...

Inverse CeO2/CuO Catalyst As an Alternative to Classical Direct Configurations for Preferential Oxidation of CO in Hydrogen-Rich Stream

Abstract: A novel inverse CeO(2)/CuO catalyst for preferential oxidation of CO in H(2)-rich stream (CO-PROX) has been developed on the basis of a hypothesis extracted from previous work of the group (JACS 2007, 129, 12064). Possible separation of the two competing oxidation reactions involved in the process (of CO and H(2), respectively) is the key to modulation of overall CO-PROX activity and is based on involvement of different sites as most active ones for each of the two reactions. Achievement of large size CuO particles and adequate CeO(2)-CuO interfacial configurations in the inverse catalyst apparently allows appreciable enhancement of the catalytic properties of this kind of system for CO-PROX, constituting an interesting alternative to classic direct configurations so far explored for this process. Reasons for such behavior are analyzed on the basis of operando-XRD, -XAFS, and -DRIFTS studies.

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Sodium-ion batteries: present and future

Abstract: Energy production and storage technologies have attracted a great deal of attention for day-to-day applications. In recent decades, advances in lithium-ion battery (LIB) technology have improved living conditions around the globe. LIBs are used in most mobile electronic devices as well as in zero-emission electronic vehicles. However, there are increasing concerns regarding load leveling of renewable energy sources and the smart grid as well as the sustainability of lithium sources due to their limited availability and consequent expected price increase. Therefore, whether LIBs alone can satisfy the rising demand for small- and/or mid-to-large-format energy storage applications remains unclear. To mitigate these issues, recent research has focused on alternative energy storage systems. Sodium-ion batteries (SIBs) are considered as the best candidate power sources because sodium is widely available and exhibits similar chemistry to that of LIBs; therefore, SIBs are promising next-generation alternatives. Recently, sodiated layer transition metal oxides, phosphates and organic compounds have been introduced as cathode materials for SIBs. Simultaneously, recent developments have been facilitated by the use of select carbonaceous materials, transition metal oxides (or sulfides), and intermetallic and organic compounds as anodes for SIBs. Apart from electrode materials, suitable electrolytes, additives, and binders are equally important for the development of practical SIBs. Despite developments in electrode materials and other components, there remain several challenges, including cell design and electrode balancing, in the application of sodium ion cells. In this article, we summarize and discuss current research on materials and propose future directions for SIBs. This will provide important insights into scientific and practical issues in the development of SIBs.

An overview of hydrogen production technologies

Abstract: Currently, hydrogen is primarily used in the chemical industry, but in the near future it will become a significant fuel. There are many processes for hydrogen production. This paper reviews the technologies related to hydrogen production from both fossil and renewable biomass resources including reforming (steam, partial oxidation, autothermal, plasma, and aqueous phase) and pyrolysis. In addition, electrolysis and other methods for generating hydrogen from water, hydrogen storage related approaches, and hydrogen purification methods such as desulfurization and water-gas-shift are discussed.

Recent advances in the liquid-phase syntheses of inorganic nanoparticles.

Abstract: The development of novel materials is a fundamental focal point of chemical research; and this interest is mandated by advancements in all areas of industry and technology. A good example of the synergism between scientific discovery and technological development is the electronics industry, where discoveries of new semiconducting materials resulted in the evolution from vacuum tubes to diodes and transistors, and eventually to miniature chips. The progression of this technology led to the development * To whom correspondence should be addressed. B.L.C.: (504) 2801385 (phone); (504) 280-3185 (fax); bcushing@uno.edu (e-mail). C.J.O.: (504)280-6846(phone);(504)280-3185(fax);coconnor@uno.edu (e-mail). 3893 Chem. Rev. 2004, 104, 3893−3946

Preparation and Characterization of Multiwalled Carbon Nanotube-Supported Platinum for Cathode Catalysts of Direct Methanol Fuel Cells

Abstract: Multiwalled carbon nanotube-supported Pt (Pt/MWNT) nanocomposites were prepared by both the aqueous solution reduction of a Pt salt (HCHO reduction) and the reduction of a Pt ion salt in ethylene glycol solution. For comparison, a Pt/XC-72 nanocomposite was also prepared by the EG method. The Pt/MWNT catalyst prepared by the EG method has a high and homogeneous dispersion of spherical Pt metal particles with a narrow particle-size distribution. TEM images show that the Pt particle size is in the range of 2-5 nm with a peak at 2.6 nm, which is consistent with 2.5 nm obtained from the XRD broadening calculation. Surface chemical modifications of MWNTs and water content in EG solvent are found to be the key factors in depositing Pt particles on MWNTs. In the case of the direct methanol fuel cell (DMFC) test, the Pt/MWNT catalyst prepared by EG reduction is slightly superior to the catalyst prepared by aqueous reduction and displays significantly higher performance than the Pt/XC-72 catalyst. These differences in catalytic performance between the MWNT-supported or the carbon black XC-72-supported catalysts are attributed to a greater dispersion of the supported Pt particles when the EG method is used, in contrast to aqueous HCHO reduction and to possible unique structural and higher electrical properties when contrasting MWNTs to carbon black XC-72 as a support.