Abstract:Octahedral ceria abrasives with varied microstructures were prepared by calcining a hierarchical precursor at 500–900 °C. The relationship between calcination temperature and microstructure, mechanical hardness and chemical activity was investigated.
“…5 ). Similar findings were reported by Li et al 38 for ceria octahedrons where the calcination temperature decreased the zeta potential of the samples. Figure 5 Explanation of the mechanism of zeta potential decrease with calcination temperature.…”
Section: Resultssupporting
confidence: 91%
“…5). Similar findings were reported by Li et al 38 for ceria octahedrons where the calcination temperature decreased the zeta potential of the samples.…”
Finding suitable non-expensive electrocatalyst materials for methanol oxidation is a significant challenge. Waste valorization of spent wastewater nanoadsorbents is a promising route toward achieving circular economy guidelines. In this study, the residual of layered double hydroxide (LDH) can be used as an electrocatalyst in direct methanol fuel cells as a novel approach. The Co–Ni–Zn–Fe LDH was prepared by the co-precipitation method followed by the adsorption of methyl orange (MO). Moreover, the spent adsorbent was calcined at different temperatures (200, 400, and 600 °C) to be converted to the corresponding mixed metal oxides (MMO). The prepared samples were characterized using XRD, FTIR, HRTEM, zeta potential, and hydrodynamic size measurements. The spent adsorbent was tested as an electro-catalyst for direct methanol electro-oxidation. The spent LDH/MO adsorbent showed a maximum current density of 6.66 mA/cm2 at a 50 mV/s scan rate and a 1 M methanol concentration. The spent MMO/MO adsorbent showed a maximum current density of 8.40 mA/cm2 at a 200 °C calcination temperature, 50 mV/s scan rate, and a 3 M methanol concentration. Both samples show reasonable stability over time, as indicated by the chronoamperometric response. Further nanoengineering of used nanoadsorbents could be a promising path to repurposing these wastes as electro-oxidation catalysts.
“…5 ). Similar findings were reported by Li et al 38 for ceria octahedrons where the calcination temperature decreased the zeta potential of the samples. Figure 5 Explanation of the mechanism of zeta potential decrease with calcination temperature.…”
Section: Resultssupporting
confidence: 91%
“…5). Similar findings were reported by Li et al 38 for ceria octahedrons where the calcination temperature decreased the zeta potential of the samples.…”
Finding suitable non-expensive electrocatalyst materials for methanol oxidation is a significant challenge. Waste valorization of spent wastewater nanoadsorbents is a promising route toward achieving circular economy guidelines. In this study, the residual of layered double hydroxide (LDH) can be used as an electrocatalyst in direct methanol fuel cells as a novel approach. The Co–Ni–Zn–Fe LDH was prepared by the co-precipitation method followed by the adsorption of methyl orange (MO). Moreover, the spent adsorbent was calcined at different temperatures (200, 400, and 600 °C) to be converted to the corresponding mixed metal oxides (MMO). The prepared samples were characterized using XRD, FTIR, HRTEM, zeta potential, and hydrodynamic size measurements. The spent adsorbent was tested as an electro-catalyst for direct methanol electro-oxidation. The spent LDH/MO adsorbent showed a maximum current density of 6.66 mA/cm2 at a 50 mV/s scan rate and a 1 M methanol concentration. The spent MMO/MO adsorbent showed a maximum current density of 8.40 mA/cm2 at a 200 °C calcination temperature, 50 mV/s scan rate, and a 3 M methanol concentration. Both samples show reasonable stability over time, as indicated by the chronoamperometric response. Further nanoengineering of used nanoadsorbents could be a promising path to repurposing these wastes as electro-oxidation catalysts.
“…13 Subsequent calcination at several hundred degrees Celsius can crystalize the ceria abrasives and decompose the impurities. 14 Mechanical milling, filtration, and static settlement processes are employed to disperse the particles into uniform-sized abrasive distributions. 15,16 The control of surface Ce 3+ ratio in ceria abrasives is beneficial in improving oxide polishing.…”
Chemical mechanical polishing (CMP) has undergone rapid advancements in global and local planarization. The synergy between the process control and the consumables is critical to overall CMP performance. In addition to optimizing consumables and equipment including a polisher, metrology, and inspection, the polishing protocol plays a crucial role in effective process management. In fabrication scenarios, protocol revision is a convenient and practical approach for problem-solving. This research focuses on the study of head sweep direction, head sweep distance, and slurry sweep effects in oxide film polishing. Sweeping toward the outside resulted in an average increase of 12.66% removal amount for ceria and 11.57% for silica compared to fixed head polishing. Moreover, a longer head sweep distance reduced non-uniformity. While the slurry sweep exhibited a non-significant effect on the removal amount, it proved valuable in optimizing the removal amount profile.
“…In order to improve the overall cutting effect of the abrasives, many studies have been carried out in controlling the particle size and distribution as well as morphology and surface features [10][11][12]. Several researchers prepared ceria abrasives by annealing carbonate or oxalate precursors or by calcining octahedral CeO 2 precursors self-assembled from spherical primary nanocrystals and found that the calcination temperature is also a critical parameter that governs the polishing efficiency and the quality of the polished surface [13,14]. In addition to these, Cheng et al attempted to dope a certain amount of lanthanide elements (La, Nd, and Yb) into cerium dioxide using the modified incipient impregnation method [15].…”
One kind of lanthanum cerium fluoride abrasive was prepared using the raw materials Ce2(CO3)3, La·Ce(CO3)3, and NH4F at temperatures of 400–1050 °C. The combined techniques of X-ray diffraction with Rietveld refinements, scanning electron microscopy, and X-ray photoelectron spectroscopy were employed to characterize the products. It was found that the materials are all made up of agglomerated irregular block-shaped particles with particle sizes in micrometer ranges. Below 850 °C, the product is a mixture of cubic CeO2 and trigonal LaF3, while above 900 °C, it is a mixture of cubic CeO2 and tetragonal LaOF. A higher calcination temperature suppresses the formation of the LaF3 phase but enhances the LaOF phase. The Ce in the prepared material is present in mixed states of Ce3+ and Ce4+, and the Ce4+/Ce3+ ratio increases with increasing calcination temperature. When the material prepared at 900 °C was used in the polishing test on K9 glass, the obtained polishing surface is very clean and flat, and the thickness difference before and after grinding is moderate, indicating its potential as an abrasive for polishing the surface of optical glass.
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