IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Garnet-Polymer Composite Membrane for Electrochemical Lithium Extraction
No full textIntroduction: The rising demand for lithium, a strategic metal for lithium-ion batteries, necessitates sustainable extraction methods with reduced environmental impact. This study explores membrane-assisted electrochemical technique to address the limitations of traditional lithium recovery processes.
Methodology: Ga-doped LLZO (Li6.25La3Ga0.25Zr2O12) was synthesized using the combustion method. PVdF-HFP polymer membranes and PVdF-HFP/Ga-LLZO polymer nanocomposite membranes were fabricated by casting method. The physicochemical properties of the prepared materials.The physicochemical properties of the synthesized Ga-doped LLZO and polymer membranes were analyzed. Lithium extraction performance of the prepared membranes was evaluated using an electrochemical cell.
Results and Discussion: The X-ray diffractograms of Ga-doped LLZO show all major peaks indexed to cubic LLZO (c-LLZO), confirming its successful synthesis. Minor impurities, such as La(OH)₃, were also detected. The PVdF-HFP diffraction pattern exhibits characteristic peaks, indicating its semi-crystalline nature.Upon the incorporation of Ga-LLZO nanoparticles, a successive decrease in peak intensity and gradual broadening of the characteristic peak was observed. This behavior signifies a reduction in the crystallinity of PVdF-HFP, which can be attributed to the interaction of nanoparticles with the polymer matrix. Such interactions disrupt the polymer chain organization, leading to enhanced interchain hopping of lithium ions, thereby improving ionic conductivity.Lithium extraction assessments revealed that the PVdF-HFP/Ga-LLZO nanocomposite membranes exhibited higher efficiency compared to pristine PVdF-HFP membranes. This improved performance can be linked to the synergistic effects of the Ga-LLZO nanoparticles, which enhance ionic pathways and contribute to better electrochemical properties.
Conclusion:The obtained results highlight the potential of such membranes for sustainable lithium recovery via electrochemical processes
Redistribution of native defects and photoconductivity in ZnO under pressure
No full textControl and design of native defects in semiconductors are extremely important for industrial applications. Here, we investigated the effect of external hydrostatic pressure on the redistribution of native defects and their impact on structural phase transitions and photoconductivity in ZnO. We investigated morphologically distinct rod- (ZnO-R) and flower-like (ZnO-F) ZnO microstructures where the latter contains several native defects namely, oxygen vacancies, zinc interstitials and oxygen interstitials. Synchrotron X-ray diffraction reveals pressure-induced irreversible phase transformation of ZnO-F with the emergence of a hexagonal metallic Zn phase due to enhanced diffusion of interstitial Zn during decompression. In contrast, ZnO-R undergoes a reversible structural phase transition displaying a large hysteresis during decompression. We evidenced that the pressure-induced strain and inhomogeneous distribution of defects play crucial roles at structural phase transition. Raman spectroscopy and emission studies further confirm that the recovered ZnO-R appears less defective than ZnO-F. It resulted in lower photocurrent gain and slower photoresponse during time-dependent transient photoresponse with the synergistic application of pressure and illumination (ultra-violet). While successive pressure treatments improved the photoconductivity in ZnO-R, ZnO-F failed to recover even its ambient photoresponse. Pressure-induced redistribution of native defects and the optoelectronic response in ZnO might provide new opportunities in promising semiconductors
Review and Outlooks on Electron Migration and Structural Modulation of Metal-Organic Frameworks for Sustainable Fuel Generation
No full textMetal–organic frameworks (MOFs) are platform materials for solar energy utilization largely due to their adaptability to be synthetically tuned and their inherent variability. The intricate mechanisms of electron transport are associated with structural changes in MOFs and influence their catalytic performance for fuel production. MOFs have been widely explored to engineer their molecular structure and tune their redox behavior. Presently, it has become pertinent to understand the role of structural features in directing the charge migration ability within the molecular framework. Our review explores the dynamic processes of electron migration through structural modulation within MOFs to enhance sustainable fuel generation. Additionally, we discuss designing heterostructures and challenges for large-scale production and their cost reduction. We have presented insights into strategic modifications in MOF structures that can significantly influence their electronic properties and catalytic efficiency. Key modifications include defect engineering, organic linker functionalization, and heterostructure formation, each aimed at boosting the photocatalytic activity. We also illustrate the strategic use of electron–hole separation to improve the efficiency in photocatalytic processes. This review accentuates the role of MOFs as versatile catalysts to advance renewable energy technologies, offering insights into their role in advancing sustainable fuel generation