“…The broad bands at 3,448 cm -1 due to adsorbed H 2 O in the material and two broad bands at 2,369 and 2,345 cm -1 for soluble CO 2 were also observed. Similar results were reported for the FT-IR analysis of apatite [26][27][28]. From the above observations, it could be confirmed that a layer of apatite forms after immersion in Hanks solution [29].…”
The passive film behavior of Ti-6Al-4V ELI (Extra Low Interstitial) alloy after a chemical treatment followed by a thermal treatment was morphologically and electrochemically characterized. The surface morphological studies were carried out using scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDAX), and Fourier Transformed-Infra Red (FT-IR) analysis to investigate the nucleation and growth of apatite on the chemically and thermally treated Ti-6Al-4V ELI alloy immersed for different durations in Hanks solution. Polarization and impedance spectroscopic (EIS) measurements were carried out in Hanks solution and the electrical parameters were obtained for the passive film using a nonlinear least square fitting (NLLS) method.
“…The broad bands at 3,448 cm -1 due to adsorbed H 2 O in the material and two broad bands at 2,369 and 2,345 cm -1 for soluble CO 2 were also observed. Similar results were reported for the FT-IR analysis of apatite [26][27][28]. From the above observations, it could be confirmed that a layer of apatite forms after immersion in Hanks solution [29].…”
The passive film behavior of Ti-6Al-4V ELI (Extra Low Interstitial) alloy after a chemical treatment followed by a thermal treatment was morphologically and electrochemically characterized. The surface morphological studies were carried out using scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDAX), and Fourier Transformed-Infra Red (FT-IR) analysis to investigate the nucleation and growth of apatite on the chemically and thermally treated Ti-6Al-4V ELI alloy immersed for different durations in Hanks solution. Polarization and impedance spectroscopic (EIS) measurements were carried out in Hanks solution and the electrical parameters were obtained for the passive film using a nonlinear least square fitting (NLLS) method.
“…Since, ZnO cannot be reduced by hydrogen before 600 °C, both peaks are assigned to the reduction of CuO to Cu 0 . The high‐temperature reduction peak corresponds to the reduction of bulk CuO with relatively large particle size, while the low‐temperature reduction peak corresponds to the reduction of dispersed CuO which interacts with ZnO . The absence of ZnO in the IS0 C catalyst leaves CuO as bulk particles of bigger size and hence the reduction temperature is also high.…”
Section: Resultsmentioning
confidence: 83%
“…The high-temperature reduction peak corresponds to the reduction of bulk CuO with relatively large particle size, while the lowtemperature reduction peak corresponds to the reduction of dispersed CuO which interacts with ZnO. [36][37][38][39][40] The absence of ZnO in the IS0 C catalyst leaves CuO as bulk particles of bigger size and hence the reduction temperature is also high. When 12 % of Cu in Cu 2 (OH) 2 CO 3 is replaced with Zn, the proportion of CuO in bulk phase decreases greatly, from 86.8 % to 31.1 %, while the interaction with ZnO and the ratio of dispersed CuO reaches 68.9 %.…”
Section: Structure and Properties Of Cuo/zno Catalyst Prepared By Calmentioning
A new methodology has been demonstrated for the synthesis of a series of phase pure (Cu1−x,Znx)2(OH)2CO3 precursors by isomorphous substitution of Zn2+ in the malachite structure. By following the present protocol, it was possible to synthesize the pure phase (Cu1−x,Znx)2(OH)2CO3 with substitution level as high as x=0.5, which is better than the maximum possible value achieved by coprecipitation method, i. e. x=0.31. The isomorphous substitution by Zn2+ leads to the change in the morphology of malachite crystals from flake‐like to regular needle‐like shape with high Zn dispersion. The activity of the calcined catalysts was increased by ∼1.5–1.7 fold for the hydrogenation of syngas to methanol as compared with those prepared from the traditional coprecipitation route. The synergy between Cu and ZnO was further demonstrated quantitatively by characterization of the catalysts treated with syngas at 250 °C.
“…On the other hand, when the reaction was performed using KBrO 3 or NaOH solutions, or pure water, the materials showed diffraction peaks related to copper carbonate (malachite, CuCO 3 .Cu(OH) 2 ) (JCPDS 01-0959). In fact, the first evidence of reaction of CO 2 with CuO was a color change from brown to light green, indicative of copper carbonate formation 32,33 :Figure 8XRD patterns of catalysts before (CuO) and after reaction for 24 h under different conditions at 25 ± 3 °C.…”
The CO2 photoreduction process to produce light hydrocarbons is known to be influenced by the presence of CuO nanoparticles, but the actual role of this material, whether as a catalyst or a reactant, has not yet been revealed. In this work, we investigate the role of CuO nanoparticles produced by a solvothermal method as a catalyst in CO2-saturated water reaction media under UV light, considering the effects of different electrolytes (Na2C2O4, KBrO3, and NaOH) and temperatures on nanoparticle phase and activity. The electrolyte strongly influenced product selectivity (NaOH led to evolution of CH4, Na2C2O4 to CO, and KBrO3 to O2) and induced CuO phase change. A long-term analysis of these processes indicated that during the initial steps, CuO acted as a reactant, rather than as a catalyst, and was converted to CuCO3.Cu(OH)2, while the as-converted material acted as a catalyst in CO2 photoreduction, with conversion values comparable to those reported in the literature.
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