Iranian Journal of Materials Science and Engineering

The redox behavior for bulk and nano silver nitrate (NSN) were studied by cyclic voltammetry technique in absence and presence of cefdinir antibiotic (CFD) using glassy carbon electrode (GCE) in 0.1 M KNO3 as supporting electrolyte at two different temperatures. Scan rates were studied for the redox reactions of bulk and nano silver nitrate (NSN) in absence and presence of cefdinir antibiotic (CFD) and mechanism of the electrode reactions were discussed. The stability constant of complexation and thermodynamic parameters for a system were evaluated

The main problem of cobalt oxide as a thermochemical heat storage material is its slow re-oxidation kinetics. In addition, redox (reduction and oxidation) behavior of as-received Co₃O₄ is degraded with increasing the number of redox cycles. To overcome this drawback, Al₂O₃ and Y₂O₃ were added to Co₃O₄ and  effect of mechanical activation time (2, 4, 8, and 16 h) on the redox behavior (weight change value/rate, redox reversibility, reduction and re-oxidation values, and particle morphologies) of Co₃O₄-5 wt.% Al₂O₃ and Co₃O₄-5 wt. % Y₂O₃ composites was investigated using thermogravimetry method. The composites were studied by SEM, EDS, and X-ray map analyses before and after redox reactions. Results showed that increasing the mechanical activation time improves the redox kinetics of Co₃O₄-5wt. % Al₂O₃ in comparison with as-received Co₃O₄. Although, the alumina-containing samples, activated in short time showed the better redox kinetics than samples activated in long time. It was found that increasing the activation time to more than 8 h for alumina-containing samples reduces the redox kinetics due to decreasing the positive effect of Al₂O₃ in controlling the particle size growth and sintering. In the case of Co₃O₄-5wt. % Y₂O₃, an increase in activation time generally reduced the redox kinetics. As a result, redox reactions in a 16 h-activated Co₃O₄-5wt.% Y₂O₃ composite was completely stopped. In addition, results showed that weak performance of Co₃O₄-5 wt. % Y₂O₃ is related to intensive sintering and growth of cobalt oxide particles during redox reactions