Synthesis and Catalytic Activity of Alkylamine-Capped Ultra-small Palladium Nanoparticles for Organic Pollutant Degradation

Mallikarjuna, K.,Raju, B. Deva Prasad,Park, Sumi,Kim, Haekyoung Springer-Verlag 2017 Journal of cluster science Vol.28 No.5

<P>Over the past few decades, increasing attention has been focused on overcoming the scarcity of fresh water resources, with the rapid effluents of dyes from modern chemical industries causing issues in photosynthetic activity of aquatic organisms. In the process of recycling wastewater, the degradation of dye pollutants such as 4-nitrophenol, methylene blue, and methyl orange has become more crucial. Noble metal (silver, gold, palladium, and platinum) materials have significant potential applications in the areas of water purification, conversion of automobile exhaust emissions, and catalysis. Ultra-small alkylamine-capped palladium nanoparticles (APd NPs) with sizes below 10 nm are synthesized using hexadecylamine (HDA) as a stabilizing material, and HDA can prevent the irreversible aggregation of small-sized nanoparticles in solution-based reactions. The fabricated ultra-small APd NPs are investigated using UV-Vis, XRD, SEM, TEM, FTIR and TGA studies. In the presence of NaBH4 as a reducing agent, the APd NPs achieve high catalytic performance toward the degradation of dye pollutants such as 4-nitrophenol, methylene blue and methyl orange.</P>

Sustainable Fabrication of Palladium Nanoparticles Using Stevia Rebaudiana Tea and Its Catalytic Activity

Mallikarjuna, K.,Raju, B. Deva Prasad,Kim, Hak-Sung American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.6

<P>Recently, sustainable synthetic processes developed during the fabrication of noble metal nanoparticles have experienced much progress because their novel optical, catalytic, sensing and electrochemical properties can be tuned by controlling their shapes and sizes. In this work, spherical palladium nanoparticles (PdNPs) were fabricated using stevia rebaudiana tea as a reducing and stabilizing material. This method can reduce the need for toxic chemicals, reduces cost, and eliminates steps in the synthesis procedure, thus making it environmentally benign. The grown PdNPs was studied using UV-Vis absorption spectroscopy. Fourier transform infrared (FTIR) and Raman spectroscopy showed the presence of functional groups of phyto-organicmoieties, which are responsible for coating PdNPs and preventing agglomeration. Morphology, distribution and size of the nanoparticles were estimated using FE-SEM and TEM studies. The crystalline purity of the synthesized PdNPs was investigated through X-ray diffraction (XRD) and small area electron diffraction (SAED) analysis. The obtained XRD pattern was compared with JCPDS data. Catalytic characteristics of PdNPs for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 were studied.</P>

Effect of cerium doping on the structural, morphological, photoluminescent and thermoluminescent properties of sodium strontium pentaborate microstructures

Joo, S. W.,Raju, B. Deva Prasad,Dillip, G. R.,Banerjee, A. N.,Jung, J. H. Springer-Verlag 2016 APPLIED PHYSICS A MATERIALS SCIENCE AND PROCESSING Vol.122 No.2

Versatile host-sensitized white light emission in a single-component K₃ZnB₅O₁₀:Dy³⁺ phosphor for ultraviolet converted light-emitting diodes

Dillip, G.R.,Kumar, Grandhe Bhaskar,Bandi, Vengala Rao,Hareesh, M.,Deva Prasad Raju, B.,Joo, S.W.,Bharat, L. Krishna,Yu, Jae Su ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.699 No.-

<P><B>Abstract</B></P> <P>A single-phase white-light-emitting phosphor, K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB>:Dy<SUP>3+</SUP>, has been synthesized by a conventional solid-state reaction method. X-ray diffraction (XRD) analysis was used to determine the monoclinic crystal structure of phosphors. The surface states, B 1s, O 1s, K 2p, Zn 2p, and Dy 3d of the phosphor was quantified by X-ray photoelectron spectroscopy (XPS). Diffuse reflectance spectroscopy (DRS) revealed double absorption edges at 3.27 and 5.46 eV for K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB> matrix. The formation of defect-levels, zinc interstitials ( Z <SUB> n i </SUB> ) , zinc vacancies ( <SUB> V Z n </SUB> ) , oxygen antisites ( <SUB> O Z n </SUB> ) and oxygen vacancies ( <SUB> V O </SUB> ) in K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB>:Dy<SUP>3+</SUP> phosphors were identified by photoluminescent (PL) spectroscopy. The emissions at 405 nm (violet-I), 434 nm (violet-II), and 467 nm (blue) are due to intra-band transitions of ( F X → <SUB> V Z n </SUB> ) , ( Z <SUB> n i </SUB> → <SUB> V Z n </SUB> ) and ( Z <SUB> n i </SUB> → <SUB> O Z n </SUB> ) of the host, respectively. Similarly, the emission at 517 nm (green) corresponds to the transition from free excitons to the oxygen vacancies in the host ( F X → <SUB> V O </SUB> ) . The emissions at 575 and 665 nm are assigned to the <I>f-f</I> transitions of Dy<SUP>3+</SUP> ions within the host matrix. An energy level diagram is proposed to describe the host emission and possible energy transfer from the host to dopant ions in the single-phase phosphor. The phosphor shows good thermal stability with activation energy of 0.52 eV. The combined emissions in the blue, green, yellow, and red regions resulted in white light emission with CIE coordinates of (0.256, 0.258) on the CIE diagram.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Versatile host-sensitized white light emission, K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB>:Dy<SUP>3+</SUP> phosphor was synthesized. </LI> <LI> Defect-related surface analysis of phosphor was studied by XPS. </LI> <LI> Energy level diagram was designed to show host to dopant energy transfer process. </LI> <LI> The phosphor has shown good thermal stability with activation energy of 0.52 eV. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Structural studies of a green-emitting terbium doped calcium zinc phosphate phosphor

Ramesh, B.,Dillip, G.R.,Rambabu, B.,Joo, S.W.,Raju, B. Deva Prasad Elsevier 2018 Journal of molecular structure Vol.1155 No.-

<P><B>Abstract</B></P> <P>In this study, a new green emitting CaZn<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>:Tb<SUP>3+</SUP> phosphors were synthesized through solid-state reaction route. The phosphors were characterized structurally by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). All the synthesized phosphors were crystallized in triclinic crystal structure with <I>P</I> 1 ¯ space group. The phosphate groups in the phosphors were confirmed by FTIR analysis. The surface elements O <I>1</I>s, P <I>2</I>p, Ca <I>2</I>p, Zn <I>2</I>p and Tb 3<I>d</I> were studied by high-resolution XPS spectra. Upon excitation at 378 nm, the dominant green emission of CaZn<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>:Tb<SUP>3+</SUP> phosphors at 542 nm were noticed in the emission spectra. For various emission wavelengths (at 435 and 489 nm) and constant excitation wavelength (at 378 nm), the decay curves have shown two different decay dynamics of phosphors. The lighting properties such as Commission International de l’Eclairage (<I>x</I> = 0.319, <I>y</I> = 0.398) and color temperature (5995 K) were calculated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A green emitting CaZn<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>:Tb<SUP>3+</SUP> phosphors were synthesized. </LI> <LI> Chemical bonds of PO, CaO, ZnO and TbO were investigated by XPS. </LI> <LI> The phosphor has two different decay dynamics upon various emissions. </LI> <LI> Chromaticity coordinates were located in green region of visible spectrum. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Luminescence properties of CaZn₂(PO₄)₂:Sm³⁺ phosphor for lighting application

Ramesh, B.,Dillip, G.R.,Reddy, G. Rajasekhara,Raju, B. Deva Prasad,Joo, S.W.,Sushma, N. John,Rambabu, B. Elsevier 2018 Optik Vol.156 No.-

<P><B>Abstract</B></P> <P>A high-temperature solid state reaction route was employed to synthesize the phosphate based new orange-red emitting trivalent samarium (Sm<SUP>3+</SUP>) ions doped calcium zinc phosphate (CZP: CaZn<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>) phosphor. The crystalline phase formation was studied by X-ray diffraction analysis. The surface properties of the phosphor were investigated by X-ray photoelectron spectroscopy. Under the excitation of 402 nm, the emission spectra of CZP:Sm<SUP>3+</SUP> has several peaks and the dominant peak at 596 nm was ascribed to <SUP>4</SUP>G<SUB>5/2</SUB> → <SUP>6</SUP>H<SUB>7/2</SUB> transition. The concentration quenching effect of Sm<SUP>3+</SUP> in CZP phosphor was observed for 5 at%. The mechanism of energy transfer between similar Sm<SUP>3+</SUP> ions was determined to be quadrupole-quadrupole interaction. The decay curves of all phosphors were well fitted to the first-order exponential function. The chromaticity coordinates were located in the orange-red region of the chromaticity diagram. Therefore, these results suggest that the orange-red emitting new CZP:Sm<SUP>3+</SUP> phosphor to be used in the phosphor-converted white light emitting diodes.</P>