Efficient Access of Voltammetric Charge in Hybrid Supercapacitor Configured with Potassium Incorporated Nanographitic Structure Derived from Cotton (Gossypium arboreum) as Negative and Ni(OH)2/rGO Composite as Positive Electrode

Interfacial Coupling of Graphene with Nickel Nanoparticles for Water Splitting and Urea Oxidation: A Spectroelectrochemical Investigation

Nickel nanoparticle and graphene interfaces of various stoichiometries were created through electrodeposition techniques. The catalytic behavior of the electrodeposited films was investigated through spectro-electrochemical methodologies. UV-vis absorbance spectra of the electrodeposited films are significantly different in the air and alkaline medium. Furthermore, UV-vis and Raman spectroscopy confirmed the coupling of Ni nanoparticles (Ni-NP) with the graphene framework, along with NiO and Ni(OH)2 . A combination of Raman and impedance spectroscopy revealed that the surface adsorption and charge transfer properties of the electrodeposited films are entirely dependent on the defects on graphene structure as well as distribution of Ni-NP on graphene. The electrodeposited films possess heterogeneous catalytic properties with a low overpotential of 50 mV (10 mA/cm-2 ) for hydrogen evolution reaction, as well as 601 mV and 391 mV (at 50 mA/cm-2 ) for the oxygen evolution reaction and urea oxidation reaction, respectively. In addition, eelectrodeposited samples show extraordinary overall water splitting performance by achieving a current density of 10 mA/cm2 at a very low applied potential of 1.38 V. This synergistic coupling of Ni and graphene renders the electrodeposited samples promising candidates as electrodes for overall water splitting in alkaline and urea-supplemented solutions.

CO2 activation of bamboo residue after hydrothermal treatment and performance as an EDLC electrode

CO₂ activation of the solid residue of bamboo after hydrothermal treatment, which is used for the production of xylo-oligosaccharide, was investigated in detail. The reference temperature for carbonization and CO₂ activation was 800 °C. The activated carbon from a solid residue was demonstrated to have a higher potential for making EDLC electrodes than bamboo activated carbon thanks to its very low ash content (almost 0) and high porosity structure with a BET surface area up to ca. 2150 m² g⁻¹. The electrochemical performance of ELDC electrodes prepared from solid residue-derived activated carbon in 1 M H₂SO₄ aqueous solution was measured and well compared with carbon from bamboo. Through investigation, it is clear that the capacitance of the electrode made from the solid residue has a better capacity than that of raw bamboo.

CO₂ activation was performed on hydrothermally treated bamboo for the preparation of an EDLC electrode.

Layer-by-layer inkjet printing GO film and Ag nanoparticles supported nickel cobalt layered double hydroxide as a flexible and binder-free electrode for supercapacitors

Inkjet printing is an attractive technique in the field of flexible electronics due to the direct writing, digital controls and non-contact operation process. In this work, we successfully printed graphite oxide and Ag nanoparticles on the substrate of flexible carbon cloth to form a flexible, conductive and hydrophilic layer, which could be used as a new substrate with an electron transport layer of large surface area. In addition, Ni-Co LDH nanosheets as the main active materials were synthesized for improving the electrochemical activity via a convenient electrochemical deposition method. The binder-free Ni-Co LDH/Ag/rGO@CC electrode exhibits outstanding electrochemical performance along with a high capacity of 173 mA h g^-1 at 1 A g^-1. Moreover, an asymmetric supercapacitor (ASC) was assembled with Ni-Co LDH/Ag/rGO@CC electrode as the positive electrode materials and activated carbon coated CC as the negative electrode materials, showing a high capacity of 95 mA h g^-1 at 0.6 A g^-1, and maximum energy density of 76 Wh kg^-1 at a power density of 480 W kg^-1.

Carbon-Induced Generation of Hierarchical Structured Ni0.75Co0.25(CO3)0.125(OH)2 for Enhanced Supercapacitor Performance

Hierarchical nanostructures with heteroatom doping have been considered as an important component in electrode materials for advanced supercapacitors. Herein, with the aid of C, N, and S codoped Ni_0.75Co_0.25(CO₃)_0.125(OH)₂/C (NSH) with a hierarchical structure was synthesized through a facile one-step hydrothermal method. Notably, it is the first report on a carbon precursor as a structure inducer for designing a three-dimensional (3D) carnation-like hierarchical structure. Thanks to the carbon induction effect and the introduction of N/S dopants, the obtained NSH with a 3D architecture exhibits superior performances as electrode materials for supercapacitors. For example, NSH offers a high specific capacity of 277.3 mAh/g at 0.5 A/g. Moreover, the assembled NSH//reduced graphene oxide hydrogel-based hybrid supercapacitor exhibits high energy densities of 44.4 and 11.7 Wh/kg at power densities of 460 W/kg and 9.8 kW/kg, respectively. This result opens up opportunities for carbon-induced methods to control the morphology and structure of other similar materials.

Synthesis of Ni/Co/Al-layered triple hydroxide@brominated graphene hybrid on nickel foam as electrode material for high-performance supercapacitors

The determined need for a sustainable energy economy has evoked the increasing interest of researchers concerning the discovery of smart material designs of layered double hydroxide (LDH) nanocomposites for energy-based applications.