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Nanosensor Laboratory
Published in Vinod Kumar Khanna, Nanosensors, 2021
Juttukonda et al. (2006) reported the synthesis of tin oxide nanoparticles stabilized by a variety of dendritic polymers (polymers having a branching tree-like appearance). Their technique consists of the simple oxidation of an encapsulated stannate (containing SnO32− units) salt via reaction with carbon dioxide (CO2) under ambient environment. Synthesis of tin (IV) oxide nanoparticles was accomplished via the reaction of carbon dioxide with stannate ions immobilized by dendritic polymers. Stirring of an aqueous or ethanolic solution containing sodium stannate and a polymeric host was first carried out for a minimum period of 2 hours to ensure saturated host-guest chelation (to firmly bind a metal ion with an organic molecule to form a ring-shaped molecular complex in which the metal is firmly bound and isolated; the resulting ring structure protects the mineral from entering into unwanted chemical reactions). Bubbling gaseous carbon dioxide through the room-temperature mixture with vigorous stirring for 30 minutes resulted in a light-yellow solution.
Modification of polyester fabrics with Zn2SnO4 nanorods for superior self-cleaning, UV-protection and antibacterial performance
Published in The Journal of The Textile Institute, 2023
The X-Ray diffraction pattern of coated fabric with Zn2SnO4 nanorods is shown in Figure 2 confirmed the successful synthesis and fabrication of zinc stannate nanorods on the hydrolyzed polyester substrate. The well-defined diffraction peaks at 2θ = 34.2°, 35.8°, 41.6°, 51.6° and 60.4° indexing at (311), (222), (400), (511) and (440) planes of Zn2SnO4 with the cubic spinel structure relates to standard data with JCPDS file no. 24-1470 (Jain et al., 2020). Also, the peaks at 2θ values of 17°, 23.1° and 26.4° are attributed to polyester substrate. Moreover, the presence of zinc and tin elements on the fabric sample in EDX spectrum (Figure 3) indicated well synthesis and loading of zinc stannate nanorods on the polyester fabric. The preparation of zinc stannate nanorods is based on the following reaction (Ma et al., 2012; Geng et al., 2008):
Plasma electrolytic fluorination on Mg alloys: coating growth and plasma discharge behaviour
Published in Surface Engineering, 2021
Yuming Qi, Zhenjun Peng, Jun Liang, Peng Wang
It is known that PEO processes are multifactor-controlled, such as substrate materials, electrolyte compositions and electrical parameters, and their interactions [14,18]. Among these factors, electrolyte composition has a strong influence on the resultant PEO coating in terms of its composition, microstructure and various properties [3,19–22]. Simultaneously, electrolyte characteristics also affect the coating growth and discharge events during the PEO process [19,23–26]. PEO electrolytes are generally alkaline aqueous solutions [14,27]. To date, a lot of efforts have been devoted to the development of novel electrolytes. It is the new coating-forming agents (e.g. fluorozirconate, fluorotitanate, vanadate, tungstate and stannate) that were used to replace the old ones (e.g. silicate, phosphate and aluminate) [3,15–17]. The functional additives were always incorporated into PEO electrolytes, for example, fluorides, acetates and various nano-particles [18,28–32]. However, few of them are out of the scope of aqueous solutions.
Zen and electrochemical surface finishing of materials
Published in Transactions of the IMF, 2021
Laboratory electrochemists often use miniature glass cells and electrodes to study a single reaction at a well-defined electrode surface in a freshly prepared electrolyte. In practice, such conditions are never experienced; the substrate may be a large, rough, unevenly shaped polycrystalline alloy. It may support side reactions or be affected by conditions at the other electrode. For example: (1) A local increase in electrolyte pH near the cathode, due to hydrogen evolution is equivalent to local generation of hydroxyl ions and can lead to the formation of metal hydroxides or pitting due to gas sticking to the workpiece, during metal deposition. In the case of nickel the effect is mitigated by maximising the current efficiency for nickel deposition together with the use of a pH buffer, typically boric acid, H3BO3 in the bath.(2) Cupric ions, present in the bath from open-circuit corrosion of substrates or impure anodes, can spoil the appearance of the deposit and lower its purity; copper, being nobler than nickel, preferentially deposits. In an acid bath, copper deposition occurs, in preference to nickel deposition in reaction (3). During the preparation and remediation of acid nickel baths, contamination by dissolved copper can often be removed by prolonged ‘dummying’, i.e. use of a high area, often corrugated, cathode operating at low current density.(3) Passivation of tin anodes in an alkaline stannate bath involves formation of a range of thin surface hydroxide and oxide films, e.g: