Mesoporous CuCo₂O₄ nanograsses as multi-functional electrodes for supercapacitors and electro-catalysts

Abstract

Hierarchical, mesoporous CuCo 2 O 4 nanograss has been synthesized on copper foam using a simple and cost-effective hydrothermal approach followed by a post-annealing treatment. The electrodes made from the novel nanoarchitecture exhibit multi-functional electrochemical performance. They deliver an excellent specific capacitance of 796 F g -1 at a current density of 2 A g -1 in a 2 M KOH aqueous solution and a long-term cyclic stability of 94.7% capacitance retention after 5000 cycles.When applied to electro-catalytic oxidation of methanol, the current density of the CuCo 2 O 4 /Cu foam electrode in 1 M KOH mixed with 0.5 M methanol is maintained up to 27.6 A g -1 . The superior electrochemical performances are mainly due to the unique one dimensional porous acicular architecture with very large surface area and 2 porosity grown on highly conductive Cu substrate, offering faster ion/electron transfer, an improved reactivity and an enhanced structural stability. The fabrication strategy presented here is simple, cost-effective and scalable, which can open new avenues for large-scale applications of the novel materials in energy storage.Fig. 5 (a, b) Low-magnification and high-magnification TEM images of an acicular CuCo 2 O 4 nanograss leaf; (c) corresponding SAED pattern; and (d) energy-dispersive X-ray spectrum of the elements Co, Cu and O.

Facile synthesis of maguey-like CuCo2O4 nanowires with high areal capacitance for supercapacitors

“…2d). The total diffraction peaks of the XRD match well with the cubic CuCo 2 O 4 phase (JCPDS no.78-2177) [17]. The calculated value of the CuCo 2 O 4 unit cell dimension (a 0 ) for (311) plane was 8.12 Å, higher than Co 3 O 4 (8.083 Å) [28], which confirmed that the CuCo 2 O 4 was synthesized successfully.…”

“…This advanced configuration for maguey-like CuCo 2 O 4 nanowires electrode schematically illustrated in Fig. 6b, which distinguishes from the capacitance increasing of those normal nanostructure in previous reports [17,25,26,29], where only the nanowires provided single channel for charge transition. Based on these observations, maguey-like CuCo 2 O 4 nanowires electrode has the following characteristics beneficial to capacitance improvement.…”

“…Finally, maguey-like nanowires could also provide extra path for direct charge transport to current collector in addition to the conductive CuCo 2 O 4 nanowires (the black arrows, Fig. 6b), which led to a lower charge-transfer resistance of the maguey-like CuCo 2 O 4 nanowires electrode than that of the CuCo 2 O 4 nanowires electrode [17,25,26,28]. As a result, maguey-like CuCo 2 O 4 nanowires electrodes could have a much improved overall electrochemical performance including an increase of specific/areal capacity, the rate capability and cycling stability.…”

“…Comparing to the powder electrode, it was shown that direct growth of electrode materials arrays on conductive substrates [29][30][31][32][33] could conquer the shortcoming compared to the power electrode. For example, CuCo 2 O 4 nanograss on a Cu foam substrate has hold specific capacitances of 796 F g -1 at 2 A g -1 [17]. So, great effort is still needed for pursuing more outstanding electrochemical performance of CuCo 2 O 4 .…”

General Synthesis of Porous Mixed Metal Oxide Hollow Spheres with Enhanced Supercapacitive Properties

“…[13][14][15][16] Unfortunately, poor conductivity and structural collapse are still severe weakness that limit full electrochemical reactions, resulting in fast capacity decay. Many approaches, such as controlling nanostructures [17][18][19][20] and synthesizing MMO/Ni substrates [21][22][23] and MMO/carbon hybrids [24][25][26] have been developed to further improve their electrochemical performance.…”