<p>Thermodynamics and kinetic analysis of carbon nanofibers as nanozymes</p>

Abstract

Purpose: Evaluation of structural features, thermodynamics and kinetic properties of carbon nanofibers (CNFs) as artificial nanoscale enzymes (nanozyme). Methods: Synthesis of CNFs was done using chemical vapor deposition, and transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to provide information on the morphology, elemental monitoring and impurity assay of the CNFs. The thermal features of the CNFs were evaluated using differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) derivative and TGA. The calculated thermo-physical parameters were melting temperature (Tm), weight loss maximum temperature (T max) and enthalpy of fusion (ΔH fusion). Catalytic activity was assayed by a 4-aminoantypyrine (4-AAP)-H 2 O 2 coupled colorimetric system by UVvisible spectroscopy. Results: FE-SEM and TEM analysis demonstrated parallel graphitic layers and uniformity of atomic orientation and morphology. The EDX spectra approved carbon element as major signal and presence of partial Ti as impurities of CNFs during CVD process. The DTA thermogram showed the endothermic process had a maximum temperature of 82.27°C at −15.48 mV and that thermal decomposition occurred at about 200°C. The TGA-differential gravimetric analysis thermogram showed that T max was 700°C. The DSC heat flow curve showed a melting temperature (Tm) of 254.52°C, ΔH fusion of 3.84 J^.g −1 , area under the curve of 58.58 mJ and T e (onset) and T f (end set) temperatures of 246.60°C and 285.67°C, respectively. The peroxidase activity of the CNFs obeyed the Michaelis-Menten equation with a double-reciprocal curve and the calculated K m , K cat and V max kinetic parameters. Conclusion: CNFs as peroxidase nanozymes are intrinsically strong and stable nanocatalysts under difficult thermal conditions. The peroxidase activity was demonstrated, making these CNFs candidates for analytical tools under extreme conditions.

Viscose Support for Assembly of Cu2O and TiO2: Antimicrobial, Photocatalytic, and Recoverable Composites for Cr(VI) Removal

“…Meanwhile, within the first stage, a steady state of weight loss was obviously shown and no detection of weight loss was estimated for viscose at 0–200 °C; however, in the case of Cu 2 O@TiO 2 @viscose composite no weight loss was estimated even under vigorous heating up to 300 °C, which could be attributed to successive domination of metal oxides that are thermally stable in detection temperature. However, at more elevated temperature (up to 300 °C), 48% of the weight loss in the case of viscose, but for Cu 2 O@TiO 2 @viscose composite, it was estimated to be 8%. , Moreover, 3.9%/min was lost at 300 °C in case of viscose, and 0.2%/min was only lost at 300 °C for the Cu 2 O@TiO 2 @viscose composite. Additionally, differential scanning calorimetry results are presented in Figure S1.…”

In Situ Prepared Solar Light‐Driven Flexible Actuated Carbon Cloth‐Based Nanorod Photocatalyst for Selective Radical–Radical Coupling to Vinyl Sulfides

“…4b) and differential thermal analysis (DTA) (Fig. 5a) (38,39). TGA, DTA and DTG analysis of T, PPIBNR, and PPIBNR-FACC were performed at the temperature range from 25 to 900°C with a heating rate of 10°C min À1 under an inert atmosphere.…”

Ultrahigh sun‐light‐responsive/not responsive integrated catalyst for C‐S arylation/humidity sensing

“…These results were also supported by DTA and DTG curves, shown in Figure 2 (b) and figure 2 (c), respectively. [31,32] The X-ray diffraction (XRD) patterns of TBPCOF and TBPCOF-fACC photocatalyst are shown in supporting information,fFigure S8. As shown in the XRD patterns of TBPCOF, three intense peaks at 2-theta angle value of 14.2°, 25°, and 36.9° were observed which show crystalline nature of TBPCOF.…”