Overvoltage and low current are observed for ethanol electrooxidation on the surface of many unmodified electrodes. Therefore, it is desirable to use a suitable catalyst for ethanol electrooxidation to increase the current. This research introduces a new sensor to catalyze ethanol oxidation in an alkaline environment. This new Zn-Mn-Co LDH/PolyPyrrole/GCE nanocomposite sensor exhibits high catalytic activity for ethanol electrooxidation. It changes the oxidation potential of ethanol to a less positive potential. To identify this proposed sensor, X-ray diffraction (XRD), Brauner Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, field emission scanning electron microscopy (FESEM), thermal analysis (TGA), high-resolution transmission electron microscopy (HR-TEM) and cyclic voltammetry techniques were used. Ethanol electrooxidation was investigated by cyclic voltammetry technique. The effects of scan rate and ethanol concentration on the ethanol oxidation peak have been investigated. The proposed sensor showed long-term stability. This prepared nanocomposite can be used as an anode catalyst for ethanol fuel cells.
Natural convection could arise even at ultra-low redox concentration solutions (1–10 mM). Models such as convection–diffusion layer model and spontaneous convection model have been established to describe this phenomenon. However, the driving forces as well as the parameters that influence this natural convection effects are still not clear. Herein we investigated the effects of viscosity on natural convection by introducing sodium alginate (SA), which enhanced viscosity without changing the diffusion coefficient of the redox couple. Resultantly, it allowed us to obtain the relationship between microscopic flow of solutions and the thickness of natural convection layer. Moreover, wire electrodes with various diameters were also tested to reveal the natural convection effects on mass transfer. An empirical equation was established to describing the influences of solution viscosity and diameter of wire electrode on the thickness of natural convection layer in ultra-low redox concentration solutions.
Oxygen reduction is one of the core steps of non-emissive zero carbon energy conversion. Therefore, enhancement of its sluggish kinetics is extremely important. Very recently researchers focused on oxygen electrocatalysis at porous polymers. Here we applied the non-metalated and pyrolysis free hypercrosslinked polymers with high specific surface area and abundant active sites. Electrode modified with the copolymer prepared from the twisted triphenylbenzene and N containing triphenyl amine exhibits electrocatalytic ORR in alkaline medium. Tafel slope value (0.067 V dec−1) indicates the efficient electrocatalytic activity and fast reaction kinetics. The lack of H2O2 product detected by scanning electrochemical microscopy suggests 4-electron path. The electrocatalytic activity of electrodes modified with hypercrosslinked polymers prepared from single monomers is also seen.
Supercapacitors will play a crucial role in the future energy landscape due to their high power density and extended cycle stability. However, energy density tends to be relatively low, partly because of conventional heavy current collectors, also posing sustainability issues. It is crucial to integrate lightweight, flexible current collectors and environmentally friendly active materials while maintaining the performance of the supercapacitor. Here we report on a metal-free supercapacitor using a carbon paper current collector and onion like carbon (OLC). The electrodes were fabricated through a scalable and flexible spray-coating process using onion-like carbon ink. Higher capacitances were observed for the paper-based electrode (24.1 F/g, 34.9 mF/cm2) compared to 22.5 F/g (31.5 mF/cm2) for aluminium collectors at scanrates of 2.5 mV/s over a voltage window of 2.5 V. At elevated scanrates of 100 mV/s–5 V/s, the actual operating window of a supercapacitor, the paper-based electrode offers a significantly enhanced performance. Stability tests demonstrated a capacitive retention of 98 % for both electrodes after 10,000 cycles. The utilization of onion-like carbon as the active material and a paper-based current collector enables the development of a fully carbon-based supercapacitor system, without compromising its electrochemical performance. This approach introduces a metal-free OLC supercapacitor and promotes environmental sustainability by reducing the dependence on conventional metal-based components and provides a more resource-efficient solution to address the energy storage needs.