Search

The utilization of nickel hydroxide and manganese dioxide solely as high‐performance supercapacitive materials is hindered by their low capacitance retention and electrical conductivity. As Ni(OH)2 and MnO2 give a synergistic effect, porous Ni(OH)2‐MnO2 nanosheets with a thickness of 9 nm are successfully grown on carbon fiber (CF) via a single‐step hydrothermal co‐deposition method. Multi‐walled carbon nanotubes (CNT) are grafted with maleic anhydride (MA) through plasma‐grafted process, followed by thiol‐ene reaction to synthesize CNT‐MA−S (CMS) to increase their aqueous dispersion behavior. The electrochemical properties of Ni(OH)2‐MnO2 are further enhanced by dip‐coating CMS on nanosheets. The composition and morphology of CMS and Ni(OH)2‐MnO2 nanosheets are characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (ESCA), transmission electron microscopy (TEM), thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR), and Raman spectroscopy. The electrochemical characteristics of fabricated electrodes are analyzed using cyclic voltammetry and chronopotentiometry methods. CF−Ni(OH)2‐MnO2/CMS electrode is successfully synthesized without using any binder, exhibited ultrahigh specific capacitance (2049 F g−1 at a current density of 1 A g−1), and excellent capacitance retention (>80 %) at 2 A g−1 charge/discharge rate after 5000 cycles. [ABSTRACT FROM AUTHOR]

The rapid and straightforward detection of formaldehyde (FA) in the environment is crucial for preventing the accidental inhalation of FA and limiting skin exposure to FA. In this study, we developed a simple nickel‐based electrocatalytic electrode on carbon nanofibers (CNFs−Ni), which is suitable for rapidly detecting FA at room temperature. Centrifugal electrospinning was used to obtain polyacrylonitrile (PAN) nanofibers, which was subsequently stabilized and carbonized to fabricate the CNFs. Carbonization of the CNFs occurred at various temperatures (Tc=1200, 1300, 1400, and 1500 °C). PAN CNFs served as a highly conductive template for electroless plating under a magnetic field of 500 G to grow acicular nickel. The amperometric responses of the CNFs−Ni to aqueous FA were then measured. A lab‐built amperometric gas sensor (CNFs−Ni 1–8), which comprised CNFs with a reduced Ni loading, was used as the electrode for detecting gaseous FA. Scanning electron microscopy (SEM), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and chronoamperometry were used to evaluate the sensitivities of the electrodes. Within the linear range of 0.05–91.5 mM, the CNFs1400‐Ni electrode was highly sensitive for detecting aqueous FA (2592 μA mM−1 cm−2), as evidenced by the fast response time (6 s). At a low concentration of gaseous FA (0.5 ppm), the laboratory‐built FA gas sensor was stable (98.3 %) and had a fast response time (5 s) after 9 h of continuous operation. [ABSTRACT FROM AUTHOR]