Chemical insights into the roles of nanowire cores on the growth and supercapacitor performances of Ni-Co-O/Ni(OH)2 core/shell electrodes

Abstract

Nanostructured core/shell electrodes have been experimentally demonstrated promising for high-performance electrochemical energy storage devices. However, chemical insights into the significant roles of nanowire cores on the growth of shells and their supercapacitor behaviors still remain as a research shortfall. In this work, by substituting 1/3 cobalt in the Co3O4 nanowire core with nickel, a 61% enhancement of the specific mass-loading of the Ni(OH)2 shell, a tremendous 93% increase of the volumetric capacitance and a superior cyclability were achieved in a novel NiCo2O4/Ni(OH)2 core/shell electrode in contrast to a Co3O4/Ni(OH)2 one. A comparative study suggested that not only the growth of Ni(OH)2 shells but also the contribution of cores were attributed to the overall performances. Importantly, their chemical origins were revealed through a theoretical simulation of the core/shell interfacial energy changes. Besides, asymmetric supercapacitor devices and applications were also explored. The scientific clues and practical potentials obtained in this work are helpful for the design and analysis of alternative core/shell electrode materials.

Electro-Oxidation Reaction of Methanol over La2–xSrxNi1–y(Mn/Fe/Co)yO4+δ Ruddlesden–Popper Oxides

“…The CV trace in Figure a also indicated an additional minor peak at 1.36 V vs RHE (labeled as Peak III) during the forward scan and at 1.26 V vs RHE (labeled as Peak IV) during the reverse scan for La 1.4 Sr 0.6 Ni 0.9 Co 0.1 O 4+δ . The minor peak corresponds to the oxidation of Co 3+ /Co 4+ and was in accordance with previous findings in the literature. − No corresponding peaks were evident for the oxidation of Mn 2+ or Fe 2+ . Interestingly, as the scan rate was elevated from 10 to 100 mV s –1 , an increase in the peak current density was observed, indicating the formation of a more substantial layer of −OOH species enriched with Ni 3+ on the catalyst’s surface (Figure S4).…”

Ultrathin nanosheets of cobalt-nickel hydroxides hetero-structure via electrodeposition and precursor adjustment with excellent performance for supercapacitor

“…In contrast, the binary cobalt-nickel layered double hydroxides demonstrate superior electrochemical performance over single cobalt or nickel hydroxides by integrating the advantages of both components. Researchers have devoted considerable efforts to fabricate various Co-Ni hydroxide nanostructures to improve the electrochemical performance of Co-Ni hydroxides as high-performance electrode materials [22][23][24] . Sun and co-workers reported the morphology and structure evolution of the Ni-Co mixed hydroxides changing from nano-sheets, to nano-plates, nano-spheres, nano-rods and nano-particles through modulating the Co/Ni molar ratio in the initial reactant.…”

Effect of Fe Doping on the Surface Morphology and Supercapacitor Properties of Sr(OH)2 Thin Films: A Fractal Approach

“…1,36 It is interesting to note that the electrode−electrolyte interface with fractal geometry offers an improved electrode−electrolyte interface. 1,9,36,37 Fractal objects have a higher surface area as compared to the substrates. 9,38,39 Many researchers have reported that the performance of a supercapacitor is enhanced with metal doping as well as the formation of nanocomposites.…”

“…9,38,39 Many researchers have reported that the performance of a supercapacitor is enhanced with metal doping as well as the formation of nanocomposites. [9][10][11]36,40,41 Recently, our group reported a high specific capacity (∼413 C g −1 ), energy density (∼45.95 Wh kg −1 ), and power density (∼2.6 kW kg −1 ) in an Sr(OH) 2 -based supercapacitive electrode. The natural abundance, low cost, electrochemical performance, and environment-friendly nature of this material has made it an efficient candidate that has attracted the researchers to use it as a new electrode for supercapacitors.…”

“…Recently, a fractal study of a Cu-doped Sr­(OH) 2 thin film as a supercapacitive electrode reported that the supercapacitive value enhances with increase in fractal dimension . This suggests that surface engineering can be an efficient tool to adjust the surface area of electrodes with fractal porosity/granularity for further improvements in the performance of devices. , It is interesting to note that the electrode–electrolyte interface with fractal geometry offers an improved electrode–electrolyte interface. ,,, Fractal objects have a higher surface area as compared to the substrates. ,, …”