Cobalt/Nickel Ions-Assisted Synthesis of Laminated CuO Nanospheres Based on Cu(OH)₂ Nanorod Arrays for High-Performance Supercapacitors

Abstract

The development for environmentally friendly energy conversion and storage equipment has given rise to tremendous research efforts as a result of the growing requirements for environmental friendly resources and the rapid consumption of traditional fossil fuel. Herein, a novel hierarchical CoO/NiO–Cu@CuO heterostructure is successfully devised and synthesized. Cobalt/nickel ions are used to generate novel CoO/NiO-doped laminated CuO nanospheres through the facile in situ wet oxidation combined with cation exchange and calcination strategies. As a result, the electrochemical supercapacitance of the as-prepared CoO/NiO–Cu@CuO electrode can reach 875 C cm–2 (2035 mF cm–2), which exhibits much better electrochemical performance compared to other precursor electrodes at a same current density of 2 mA cm–2. Moreover, an excellent rate capacity of 1395 mF cm–2 (50 mA cm–2) can be achieved when measured at a relative high current density; 90.3% of the initial supercapacitance remains even after 5000 cycles. Furthermore, the as-prepared hierarchical hybrid of laminated CoO/NiO–CuO nanospheres in situ generated on three-dimensional (3D) porous Cu foam is applied to prepare a solid-state asymmetric supercapacitor equipment unit. The fabricated equipment unit shows an energy density of 69.3 W h kg–1 at a power density of 1080 W kg–1. Additionally, the commercially applied 2.5 V light-emitting-diode indicator with blue light can be energized for 4 min when two as-fabricated supercapacitor devices are in series connection. The unique hierarchical heterostructure of the novel laminated nanospheres combined with the 3D grid structure brings about the outstanding electrochemical capacitor performances. This strategy for the fabrication of hierarchical heterostructure electrodes could have an enormous potential for high-performance electrochemical equipment.

Encapsulation of Co3O4 Nanocone Arrays via Ultrathin NiO for Superior Performance Asymmetric Supercapacitors

“…[ 4 ] : g‐C 3 N 4 ‐NiCo‐LDH; [ 53 ] Ref. [ 5 ] : R‐Co 3 O 4 /CoS; [ 30 ] Ref. [ 6 ] :Co 3 O 4 /NHCS; [ 54 ] Ref.…”

“…[1,2] Highly efficient sustainable energy storage in terms of energy conservation and low cost is vital and held questionable in the research community. [3][4][5] To satisfy the modern societal requirements, the technological advancement in electrochemical energy storage devices, such as batteries, supercapacitors, and fuel cells have been exponential over the decades. [6][7][8][9] Electrochemical supercapacitor systems have received tremendous attention owing to its high power density and boosted charge-discharge cycles in contrast to the current density and about 92.3% capacity was retained after 10 000 cycles.…”

Direct Utilization of Photoinduced Charge Carriers to Promote Electrochemical Energy Storage

“…[ 29 ] Derived from the intercept on the x axis, their equivalent series resistance (ESR) values are 0.64 Ω (OC light off), 0.65 Ω (OC light on), 0.62 Ω (0.1 V light off), and 0.60 Ω (0.1 V light on), respectively. [ 30 ] In the low‐frequency region, the linear part connected with the diffusion limitation shows a typical capacitive behavior. [ 31 ] Furthermore, the slopes with light irradiation (OC light on, 0.1 V bias light on) are higher than the corresponding slopes without light irradiation (OC light off, 0.1 V bias light on), which indicates a better electric conductivity.…”

Oriented Catalytic Oxidation Induced Fabrication of CuO/Mn3O4 Hierarchical Arrays as Binder‐Free Electrodes for High‐Performance Supercapacitor

“…[1][2][3][4][5][6] Among the typical electrode materials for supercapacitors, such as carbon materials, [7,8] conducting polymers, [9,10] metal More recently, with the assistance of Co 2+ /Ni 2+ etching or Mn 2+ / Ni 2+ deposition, Zhang et al have separately prepared CoO/ NiO-Cu@CuO and NiMn-LDH@CuO/CF heterostructures on Cu foams, which, as a result, both exhibit much enhanced electrochemical performance compared with the single CuO precursors. [29,33] In addition, instead of designing the CuO-based hybrid nanorod arrays as above, one-pot hydrothermal method followed by annealing has also been adopted for the preparation of NiO-CuO hollow particles on Ni foams, which could introduce abundant oxygen vacancies in the hybrids to promote their electronic conductivity and thereby increase the electrochemical capacitance. [24] Nevertheless, the specific capacity of above CuO-based hybrids still can't reach the optimal value close to the theoretical capacity of CuO, and more seriously, most of them exhibit an undesirable cycling performance below 10 000 cycles during charging/discharging reactions.…”

“…[25,26] In particular, when designed to grow on conductive substrates, the CuO-based hybrid materials could be directly applied as binderfree electrodes for supercapacitors, and generally exhibit much enhanced electronic conductivity and structural stability. [27][28][29][30][31][32][33] Up to now, most of such CuO-based hybrids as binder-free electrodes are usually derived from the Cu(OH) 2 nanoarray templates, which are in-situ grown on Cu or Ni substrates, simply by thermal dehydration. Through subsequent chemical deposition or etching with transition metal salts under specific reaction conditions, the generated CuO nanorod arrays from the Cu(OH) 2 nanoarray templates would evolve into the target products with various hybrid components and rich nanostructures.…”