Bio-inspired synthesis of NaCl-type CoxNi1−xO (0 ≤ x < 1) nanorods on reduced graphene oxide sheets and screening for asymmetric electrochemical capacitors

Abstract

A bio-inspired approach has enabled the first synthesis of Co x Ni 1Àx O (0 # x < 1) nanorods on reduced graphene oxide (RGO) sheets. The key is the crystallization process from amorphous precursors in a disordered and hydrated state being able to take compositions arbitrarily different from that of the known stable mixed oxide NiCo 2 O 4 . This success has permitted further screening of the compositions for electrochemical capacitors. Co x Ni 1Àx O/RGO nanocomposite electrodes achieve a peak specific capacitance when the Co/Ni molar ratio is close to 1. ). Even at a high power density of 3614.0 W kg À1 , the asymmetric cell could still maintain an energy density of 28.0 Wh kg À1. There was only a <4% loss of the initial specific capacitance after 1000 cycles of charge/discharge at 2 A g À1 .

Nickel Cobaltite Nanostructures for Photoelectric and Catalytic Applications

“…[ 64,65 ] Other than spinel NiCo 2 O 4 , Co 2+ and Ni 2+ , because of their similar unit cell structures, also can form homogeneous solid solutions in any molar ratio with a NaCl-type crystal structure as Co x Ni 1-x O. Yang and co-workers reported NaCl-type Co x Ni 1-x O (0 < x < 1) nanorods serving as a highperformance electrochemical capacitors with the capacitance reaching a maximum at a 1:1 molar ratio of Co/Ni. [ 66 ] The properties of NiCo 2 O 4 nanostructures are dependent on the method of preparation. [ 67 ] Marco and co-workers found that the NiCo 2 O 4 nanostructures with similar nominal compositions prepared by different methods exhibit notably different Ni 2+ and Co 2+ ion distributions.…”

Flexible Cellulose Paper‐based Asymmetrical Thin Film Supercapacitors with High‐Performance for Electrochemical Energy Storage

“…[24][25][26] Ni 2p spectrum of the Co 2 NiO 4 nanosheeets is shown in Figure 2 c. The Ni 2p 3/2 peak at 855.9 and Ni 2p 3/2 peak at 857.4 eV inidcate the coexistence of Ni 2+ and Ni 3+ . [27][28][29] XPS spectrum of O1s in Figure 2 d shows the peak O I at 529.2 eV corresponds to nickel-oxygen bonds while the peak O II at 531.2 eV is ascribed to cobalt-oxygen bonds. [ 24,25,30 ] XPS analysis also show that the atom ratio of Co, Ni and O is 22.9 at%, 11.…”

电化学离子交换法辅助制备可用作高性能超级电容器电极的Co3O4/NiCo2O4纳米复合材料

“…The Nyquist plots of Co 3 O 4 / Table S1. In the low frequency region, they have a similar vertical line, indicating a more ideal capacitive property [45]. In the high frequency region, the internal resistance of the Co 3 O 4 /NiCo 2 O 4 (0.25 Ω) is lower than that of the pristine Co 3 O 4 electrode (2.31 Ω), which is deduced by the introduction of the Ni ions.…”