α‐MnO₂‐Sensitized SrCO₃−Sr(OH)₂ Supported on Two‐Dimensional Carbon Composites as Stable Electrode Material for Asymmetric Supercapacitor and Oxygen Evolution Catalysis

Abstract

We developed α‐MnO2‐sensitized SrCO3−Sr(OH)2 supported on amine functionalized reduced graphene oxide (rGO) nanosheets (denoted as MSSG) to understand the energy storage and the electrocatalytic properties. Three different nanocomposites with the tuned Mn precursors such as 0.625, 1.25 and 2.5 mmol, were prepared and denoted as MSSG‐1, MSSG‐2 and MSSG‐3, respectively and loaded on the electrode's surface. Among the nanocomposites loaded electrodes, MSSG‐1 loaded electrodes exhibit a maximum specific capacitance (Csp) of 792 F/g at 3.5 A/g current density and is morphologically stable even after 5000 cycles with a retention level of 95.9 %. With this outcome, the assembled asymmetric supercapacitor (AASC) device is mechanized effectively to power the light emitting diodes (LEDs) for 62 s continuously. In addition, the prepared electrode materials were examined for oxygen evolution reaction (OER) for enhanced electrocatalytic performance with low overpotential (346 mV at 10 mA cm−2 current density) and Tafel slope (97 mV Dec−1). In addition, the long‐term durability study represents a stable performance of the loaded electrode lasting up to 72 h. Notably, the mesoporous nanostructures at the electrode surface offer an effective synergistic effect between SrCO3−Sr(OH)2 supported on NH2‐functionalized rGO nanosheets (SSG) and α‐MnO2.

Controlled growth of Sb2S3 nanorods on phosphorus doped reduced graphene oxide for enhanced overall water splitting

“…Importantly, the as-prepared Sb 2 S 3 @P-rGO possesses rich active sites and a large specific surface area, and the P-rGO conductive network provides a smooth pathway for efficient electron transfer reactions during the enhanced water splitting reaction. Meanwhile, the reaction mechanism of the HER involved two steps to produce H 2 gas as follows: 47 2H 2 O + Sb* + P* + 2e − ↔ Sb*−H + P*−H + 2OH − (Volmer step)2H 2 O + 2e − + Sb*−H + P*−H ↔ 2H 2 +2OH − + Sb* + P* (Heyrovsky step)…”

Synergy of Charge Storage Properties of CuO and Polypyrrole in Composite CuO-Polypyrrole Electrodes for Asymmetric Supercapacitor Devices

“…The areal capacitance of the anodes must be matched with the areal capacitance of advanced Mn 3 O 4 or MnO 2 cathodes, which showed high capacitances at the level of ∼6–8 F cm –2 in a Na 2 SO 4 electrolyte. ,, Therefore, the low areal capacitance of CuO anodes is a limiting factor for the applications of this material in asymmetric supercapacitors. It should be noted that aqueous asymmetric supercapacitors are environmentally friendly and offer advantages of enlarged voltage window and high energy and power density compared to aqueous symmetric supercapacitors. − …”