RESUMO
The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacities. It is predicted that transition metal selenide compounds will be ideal electrode materials for supercapacitors. However, the defects of poor conductivity and volume expansion of the compounds are fundamental problems that must be solved. In this work, we successfully synthesized the cobalt-nickel selenide nitrogen-doped carbon (H-CoNiSe2/NC) hollow polyhedral composite structure using ZIF-67 as a precursor. The CoSe2 and NiSe2 nanoparticles embedded in the NC polyhedral framework offer a wealth of active sites for the whole electrode. Moreover, the presence of the NC structure in the proposed composite can simultaneously lead to improved conductivity and reduce the volume effect created during the cycling procedure. The H-CoNiSe2/NC electrode provides high specific capacity (1131 C/g at 1.0 A/g) and outstanding cyclic stability (90.2% retention after 6000 cycles). In addition, the H-CoNiSe2/NC//AC hybrid supercapacitor delivers ultrahigh energy density and power density (81.9 Wh/kg at 900 W/kg) and excellent cyclic stability (92.1% of the initial capacitance after 6000 cycles). This study will provide a supercapacitor electrode material with a high specific capacity for energy storage devices.Please confirm the corresponding affiliation for the 'Ali A. Ensafi' author is correctly identified.Error during converting author query response. Please check the eproofing link or feedback pdf for details.
RESUMO
An electrochemical aptasensor has been developed to determine K+ using electrochemical impedance spectroscopy. The polyaniline (PANI) coating was first electrodeposited on a GCE. Then, the potassium-selective aptamer [G3(T2AG3)3] was adsorbed through an electrostatic force between PANI and aptamer. In the presence of K+, the single-stranded DNA is folded into the G-quadruplex configuration, which acts as a barrier against electron transfer at the GCE surface. AFM and FE-SEM images characterize the surface morphology at each fabrication stage. As the K+ concentration increased, the charge transfer resistance (Rct) increased, and the plot of ΔRct versus the logarithm of the K+ concentration is linear over a wide range of 10 pM-60 µM with a low detection limit of 3.7 pM. Finally, the proposed sensor was used to determine K+ in water, serum, urine, and fruit samples. Moreover, the binding stability of the aptamer/PANI and K+/Aptamer/PANI and the interactions between the aptamer and PANI were analyzed through molecular dynamics simulation.
