High-performance asymmetric supercapacitors of advanced double ion-buffering reservoirs based on battery-type hierarchical flower-like Co3O4-GC microspheres and 3D holey graphene aerogels

Polyethylene-Derived Activated Carbon Materials for Commercially Available Supercapacitor in an Organic Electrolyte System

We fabricated high-performance supercapacitors based on activated carbons (AC) derived from Polyethylene (PE), which is one of the most abundant plastic materials worldwide. First, PE carbons (PEC) were prepared via sulfonation, which is reported solution for successful carbonization of innately non-carbonizable PE. Then, we explored the physico-electrical changes of PECs upon a chemical activation process. Interestingly, upon the chemical activation, PECs were converted ACs with a large surface area and high crystallinity at the same time. Subsequently, we exploited PE-derived ACs (PEAC) as electrode materials for supercapacitors. Resultant supercapacitors based on PEACs exhibited impressive performance. When compared to supercapacitors based on YP50f, a representative commercial ACs, devices using PEACs presented considerably good capacitance, low resistance, and great rate capability. Specifically, the retention rate of devices using PEACs was significantly higher than that of YP50f-based devices. At the high-rate of charge-discharge situation reaching 7 A g^-1 , the capacitance of supercapacitors using PEACs was about 70% higher than that of YP50f-based devices. We assumed the carbon structure accompanying both large surface area and high conductivity endowed a great electrochemical performance at the high current operating conditions. Therefore, it is envisioned PE might be a viable candidate electrode material for commercially available supercapacitors. This article is protected by copyright. All rights reserved.

Porous Carbon Nanofiber-Modified Carbon Fiber Microelectrodes for Dopamine Detection

We present a method to modify carbon-fiber microelectrodes (CFME) with porous carbon nanofibers (PCFs) to improve detection and to investigate the impact of porous geometry for dopamine detection with fast-scan cyclic voltammetry (FSCV). PCFs were fabricated by electrospinning, carbonizing, and pyrolyzing poly(acrylonitrile)-b-poly(methyl methacrylate) (PAN-b-PMMA) block copolymer nanofiber frameworks. Commonly, porous nanofibers are used for energy storage applications, but we present an application of these materials for biosensing which has not been previously studied. This modification impacted the topology and enhanced redox cycling at the surface. PCF modifications increased the oxidative current for dopamine 2.0 ± 0.1-fold (n = 33) with significant increases in detection sensitivity. PCF are known to have more edge plane sites which we speculate lead to the two-fold increase in electroactive surface area. Capacitive current changes were negligible providing evidence that improvements in detection are due to faradaic processes at the electrode. The ΔE_p for dopamine decreased significantly at modified CFMEs. Only a 2.2 ± 2.2 % change in dopamine current was observed after repeated measurements and only 10.5 ± 2.8% after 4 hours demonstrating the stability of the modification over time. We show significant improvements in norepinephrine, ascorbic acid, adenosine, serotonin, and hydrogen peroxide detection. Lastly, we demonstrate that the modified electrodes can detect endogenous, unstimulated release of dopamine in living slices of rat striatum. Overall, we provide evidence that porous nanostructures significantly improve neurochemical detection with FSCV and echo the necessity for investigating the extent to which geometry impacts electrochemical detection.