Browsing by Author "Mishra, Mrinalini"

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Facile fabrication of titania-ordered cubic mesoporous carbon composite: Effect of Ni doping on photocatalytic hydrogen generation
(2019-07-19)
Rath, Purna Chandra
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Mishra, Mrinalini
;
Saikia, Diganta
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Chang, Jeng Kuei
;
Perng, Tsong-Pyng
Hitherto TiO2 is the most popular catalyst for photocatalytic H-2 generation and reduction of organic pollutants due to its chemical inertness, high activity, and abundance. In this work, ordered mesoporous carbon CMK-8 supported TiO2 nanoparticles loaded with non-noble metal Ni, denoted as Ni-TiO2@CMK-8 are fabricated for application in photocatalytic H-2 generation. Our results demonstrate that the developed composite exhibit exceptional photocatalytic activity for H-2 generation (3556 mu mol g(-1)) under 300 W Xe lamp irradiation (with an external quantum efficiency of 37.9%), which is around 10 times higher than pure TiO2 and 4 times that of TiO2@CMK-8. The enhanced photocatalytic performance is attributed to the well-dispersed TiO2 in the ordered mesoporous carbon structure of CMK-8. The performance is boosted by the black body-like light absorbance of CMK-8 and plasmonic effect of Ni. Enhanced UV-visible light absorbance, large surface area and the loaded Ni metal synergistically improve the charge-carrier kinetics to attain highly efficient photocatalytic H-2 generation. The Ni-TiO2@CMK-8 composite shows enhanced activity for the reduction of 4-nitrophenol as well. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Ga-doped lithium lanthanum zirconium oxide electrolyte for solid-state Li batteries
(2020-09-01)
Mishra, Mrinalini
;
Hsu, Che-Wei
;
Rath, Purna Chandra
;
Patra, Jagabandhu
;
Lai, Hong-Zheng
Cubic-phase Li7La3Zr2O12 (LLZO) garnet is a promising solid electrolyte candidate for next-generation Li batteries. As a viable approach, the desired cubic-phase formation of LLZO relies on elemental doping. In this regard, various dopants such as Al and Ga are doped into the LLZO samples, which are synthesized using a solid-state reaction method. The Al-and Ga-doped LLZO can transform to a cubic-phase garnet at 900 degrees C. After 1200 degrees C sintering, a Li2ZrO3 impurity phase is found for the Al-doped LLZO pellet, which still shows many voids and inhomogeneous particles on the surface. The Ga doping seems to be attractive since it can effectively stabilize the cubic phase and desired microstructure within 900-1200 degrees C. Based on the optimized Ga-doped LLZO (LGLZO), various electrolyte architecture designs are developed that include LGLZO pellet electrolytes with and without poly(ethylene oxide) (PEO)-lithium bis(tri-fluoromethylsulfonyl)imide (LiTFSI)-LGLZO coating, and hybrid electrolyte layers of PEO-LiTFSI, PEO-LGLZO, and PEO-LiTFSI-LGLZO composites. Li//LiFePO4 (LFP) cells with various types of electrolytes are assembled, and their charge-discharge properties are investigated. The all-solid-state Li//PEO-LiTFSI-LGLZO//LFP cell exhibits satisfactory charge storage performance, which has revealed potential for practical applications. (c) 2020 Elsevier Ltd. All rights reserved.