Composite of Zinc Using Graphene Quantum Dot Bath: A Prospective Material For Energy Storage

Abstract

The electrodeposition of a zinc–graphene composite has been achieved for the first time using a graphene quantum dot (GQD) electrode. At the GQD electrode, the electrochemical reduction of zinc ion is shifted to a lesser negative potential with the complementary anodic peak due to the oxidation of the composite shifted toward a positive potential as compared to zinc ion reduction in the GQD bath. The charge ratio of anodic to cathodic peaks is one that represents a gain of nearly ten percent over the conventional Zn/Zn2+ in the energy storage systems. In galvanostatic electrolysis, the deposition of zinc–graphene composite is carried out under neutral and acidic conditions. The X-ray diffraction of the electrolytically prepared composite shows distinct features of 2 theta reflection at 8° due to (001) plane of graphene, in addition to the characteristic reflections at 38.9°,43.2°, 54.3°, 70.1° and 90° arising from Zn at (002), (100), (101), (102) and (110). A large scale preparation of the zinc–graphene composite has been achieved with a zinc plate as the working electrode in the GQD bath. The thermogravimetric analysis (TGA) of the composite shows a distinct weight loss that is due to breakdown of the composite. The interaction of GQD with zinc ion has been examined by fluorescence spectroscopy that shows quenching of the fluorescence of GQD. Scanning electron microscopy and energy dispersion X-ray analysis (EDAX) shows a string-like structure with peaks for carbon and zinc in EDAX. The electrochemical data on zinc/zinc–graphene composite reveals that it functions ideally as a charge storage material. Contact angle measurements reveal it to have hydrophilicity.

Graphene-Boosted, High-Performance Aqueous Zn-Ion Battery

“…Moreover, the discharge plateaus of the Zn/rGO∥V 3 O 7 ·H 2 O/rGO battery demonstrated only a slight decrease from 0.74 to 0.70 V as the current density was increased (Figure S5b). Figure d shows that the new Zn/rGO∥V 3 O 7 ·H 2 O/rGO battery possessed a high specific power density of 8400 W kg –1 at 77 W h kg –1 and an energy density of 186 W h kg –1 at 216 W kg –1 based on the cathode material, which are higher than those of previously reported AZIBs. − ,− In the present study, considering that all voltage profiles were slanted, we calculated the energy density by integrating the X -axis on the charge/discharge curve.…”

“…The growth of Zn dendrites is efficiently controlled, and thus, a dendrite-free Zn anode can be obtained even at a high current density. This new AZIB shows a high specific power density of 8400 W kg –1 at 77 W h kg –1 and an energy density of 186 W h kg –1 at 216 W kg –1 , which are higher than those of previously reported AZIBs. − ,− Meanwhile, the battery also shows long-term cycle stability (>79% within the initial 1000 cycles). This novel Zn/rGO∥V 3 O 7 ·H 2 O/rGO battery system outperforms existing rechargeable batteries and shows great potential for large-scale energy storage applications.…”

Greenhouse Gas Sensors Fabricated with New Materials for Climatic Usage: A Review

“…In one approach, 3 µL of a 1 mg/mL graphene oxide solution was spin-coated on silicon fingers of 3 µm width. The graphene resistive sensor's response in the concentration range of 0-1500 ppm was measured [49][50][51][52]. Figure 16B provides the resistance response with carbon dioxide concentration at ppm levels.…”