Pan American Materials Congress: Materials for Green Energy: Materials for Green Energy
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Ramalinga Viswanathan Mangalaraja, University of Concepcion; Hector Calderon, ESFM-IPN; Julie Schoenung, University of California, Irvine; Roberto Arce, SAM - Soc. Argentina de Materiales

Tuesday 10:20 AM
February 28, 2017
Room: Marina G
Location: Marriott Marquis Hotel

Session Chair: Ramalinga Viswanathan Mangalaraja, University of Concepcion

10:20 AM  
Defect Engineering for Strong Photocatalysis of TiO2 Nanoparticles with Dopants: DFT Calculations and Experimental Verifications: Heechae Choi1; Sovann Khan2; So Hye Cho2; Taeseup Song3; 1Virtual Lab Inc. ; 2KIST; 3Yeungnam University
    Donor dopants in oxides are expected to tune optical and electrical properties. However, in most cases, the optical and electrical properties of the donor-doped TiO2 crystals are not uniform, which retards the reliable productions of highly functional materials. The main reasons mostly lie in the formation of charge-compensating defects and defect-like doping formations as implied by many of experimental evidences. Here, we investigate the defect equilibria in Nb-doped anatase TiO2 crystal, using density functional theory (DFT) calculations and thermodynamic modelling. We found that the formation of (NbTi-VTi)3- counterpart for NbTi+ reduces band gap of TiO2 by 0.1 eV and increased photocatalytic and photovoltaic efficiencies in O-rich conditions. Our experiments demonstrated that the O2-annealing narrows band gap of Nb-doped TiO2 particle and strongly enhances the photocatalytic activity, which are very well consistent with our prediction from DFT calculations.

10:40 AM  
Emission and Photocatalytic Properties of Graphene:ZnO Hybrid Nanostructures: Pandiyarajan Thangaraj1; Mangalaraja Ramalinga Viswanathan1; Udayabhaskar Rednam1; Naveenraj Selvaraj1; Karthikeyan Balasubramanian1; Mansilla Héctor D.1; David Contreras1; M.A. Gracia Pinilla1; 1University of Concepcion
    The present work reports the hybridization of ZnO nanostructures on reduced graphene oxide (rGO) surfaces and the evaluation of emission and photocatalytic properties. The reduced rGO, ZnO and rGO:ZnO hybrid nanostructures were prepared by the modified Hummer’s and solvothermal methods, respectively. The number of layers and hybridization of ZnO nanostructures on rGO surface were confirmed through high resolution transmission electron microscopy and transmission electron microscopy analyses. Raman and Fourier transform infrared spectra confirmed the hybridization of graphene and ZnO nanostructures. The photoluminescence measurement was done at 325 nm excitation and the emission properties were considerably altered through the hybridization process. The photocatalytic properties were evaluated against Acid Blue 113 (AB 113) dye and the prepared materials exhibited excellent photocatalytic properties. The degradation efficiency was significantly improved for the rGO:ZnO hybrid nanostructures.

11:00 AM  
Thermal and Electrical Conductivities of Mesoporous Nanofluids and Applications for Enzyme Catalysis: Shuang Qiao1; Ekaterina Novitskaya1; Flor Sanchez2; Rafael Vazquez-Duhalt2; Olivia Graeve1; 1University of California, San Diego; 2Universidad Nacional Autonoma de Mexico
    Fungal peroxidases are enzymes able to perform catalysis in superficial amino acids through a long-range electron transfer (LRET). The use of electrically conductive mesoporous ceramic powders appears as a new way for enzyme immobilization aiming to oxidize potential substrates directly in the mesoporous ceramic and improving the overall biocatalytic performance. Mesoporous indium oxide, zinc oxide and titanium dioxide, doped with tin, gallium, silver, and niobium, were synthesized by use of a hydrothermal reaction environment. Pore sizes were evaluated and found to be in the range of 4-13 nm. Afterwards powders were dispersed in pH 3-9 solutions to form nanofluids. Thermal and electrical conductivities of these nanofluids were measured and compared. This is the first time different kinds of doped mesoporous ceramic powders with low to high electrical conductivity values have been synthesized and tested for prospective enzyme stability and biocatalyst response.

11:20 AM  
Simulation of Bonded Magnet Performance for Renewable Energy Applications: Helena Khazdozian1; H. Ucar2; C. Hatter2; M. Kramer1; M. Paranthaman1; I. Nlebedim1; 1Ames Laboratory; 2Oak Ridge National Laboratory
    Permanent magnets based on rare earth elements (REE), such as sintered Nd2Fe14B, are central to many renewable energy applications including wind energy generation. However, REEs are considered critical materials due to the risk in their supply. Addressing such criticality requires both the development of REE-free permanent magnets and reducing the amount of REE magnets used in applications. To guide research and development, numerical techniques such as finite element methods (FEM) can be used to model the performance of materials. Finite element methods were employed to simulate the performance of anisotropic Nd-Fe-B, diluted in polymer binder to reduce the volume of the material used. A 3 MW permanent magnet generator (PMG) designed for high magnetic loading and torque density was used as a prototype system. In addition to the enhanced performance due to using anisotropic Nd-Fe-B, we will present the performance obtained for using ceramic magnets, instead of REE-based magnets.