Tuning MOF-Derived Co₃O₄/NiCo₂O₄ Nanostructures for High-Performance Energy Storage

Abstract

Highly porous Co3O4/NiCo2O4 nanostructures were synthesized using zeolitic imidazolate framework-67 (ZIF-67) nanocrystals. The oxide composite structure was adjusted by modifying ZIF-67 crystallite size and the pore structure by the coordination modulation method. After forming the zeolite imidazolate framework-67 (ZIF-67)/Ni–Co layered double hydroxide intermediate composite through reaction with nickel nitrate, the intermediate composite was heated in air to result in Co3O4/NiCo2O4. Nitrogen adsorption was used for pore structure characterization of the template and resultant oxide composite. The maximum capacitance of nanostructured Co3O4/NiCo2O4 was 770 F g–1 at a discharge current density of 1 A g–1 with acceptable cycle stability, maintaining 70% of the initial capacitance after 10,000 charge–discharge cycles.

Metal‐organic chemical vapor deposition of anatase titania on multiwalled carbon nanotubes for electrochemical capacitors

“…Unlike the usual C s decline of metal oxide‐based electrodes as the scan rate is increased because of associated low conductivities, 2 the C s of the 20 wt.% TiO 2 TiO 2 ‐MWCNT increased. This could be because surface‐controlled reactions induced by TiO 2 in electrodes increased as scan speed was raised 56 . Additionally, at 10 mV s −1 , the current work is in agreement with the work reported by Kim et al 30 (involving 4, 6, 17, and 33 wt.% of TiO 2 ) in that C s declines with an increase in TiO 2 wt.% in TiO 2 ‐MWCNT (Figure 6F).…”

“…This could be because surface-controlled reactions induced by TiO 2 in electrodes increased as scan speed was raised. 56 Additionally, at 10 mV s −1 , the current work is in agreement with the work reported by Kim et al 30 (involving 4, 6, 17, and 33 wt.% of TiO 2 ) in that C s declines with an increase in TiO 2 wt.% in TiO 2 -MWCNT (Figure 6F). However, the current work varied from this trend at higher scan rates (100 and 200 mV s −1 ) in that the 20 wt.% TiO 2 TiO 2 -MWCNT material displayed a 5000-fold improvement of C s relative to that of 5 wt.% (Figure 6F and Supporting Information: Table S1).…”

Cost-Effective MIL-53(Cr) Metal–Organic Framework-Based Supercapacitors Encompassing Fast-Ion (Li+/H+/Na+) Conductors

“…ZIF-67 MOF synthesized from 2-methylimidazole and Co­(NO 3 ) 2 exhibited a SC of 168 F g –1 , and Ni/Co-MOF and Ni-MOF delivered higher SCs of 530.4 and 306.8 F g –1 , respectively, in three-electrode configurations at 0.5 A g –1 with a LiOH electrolyte . Other reported systems include a Mn oxide/calcined ZIF-8/ nanoporous carbon composite (MNCMn60//MNCMn60)-based symmetric supercapacitor which delivered a SC of 163 F g –1 in a 1 M H 2 SO 4 electrolyte, whereas an asymmetric device (MNCMn60//MNC950) delivered a SC of 226 F g –1 in a 1 M Na 2 SO 4 electrolyte, an MOF-derived Co 3 O 4 /NiCo 2 O 4 //AC-based asymmetric device gave a SC of 288 F g –1 at 1 A g –1 , a ZIF-derived porous CoNi 2 S 2 @poly­(pyrrole)//AC asymmetric device gave a SC of 194 F g –1 at 1 A g –1 , a laser-assisted MOF-derived Ni@Carbon//AC asymmetric device gave a SC of 108 F g –1 at 1 A g –1 , and electrochemically oxidized-Co-MOF@CoNiO 2 /carbon cloth//AC device and a Ni-MOF//AC asymmetric supercapacitor with 6 M KOH and 2 M KOH electrolytes achieved the same capacitance of ∼175 F g –1 at 1 A g –1 . , Some of these values are higher, and some are lower than that obtained with the Cr-MOF.…”

A self-templating scheme for the synthesis of NiCo2Se4 and BiSe hollow microspheres for high-energy density asymmetric supercapacitors

“…In recent years, transition metal hydroxides (Ni(OH) 2 , 14 NiCo-LDH, 15 etc. ), transition metal oxides (NiO, 16 CuCo 2 O 4 , 17 Co 3 O 4 /NiCo 2 O 4 , 18 etc.) and transition metal sulfides (Co 9 S 8 , 19 NiS 2 /MoS 2 , 20 NiCo 2 S 4 , 21 etc.)…”