Self-Assembly of Metal–Organic Frameworks on Graphene Oxide Nanosheets and In Situ Conversion into a Nickel Hydroxide/Graphene Oxide Battery-Type Electrode

Abstract

Graphene oxide (GO) has been widely reported as a supercapacitor electrode. Especially, GO is usually utilized to composite with electrochemical active materials, such as transition-metal oxide/hydroxide/sulfide, due to its considerable conductivity and mechanical strength. However, the ideal design and treatment for compositing GO with active materials are still challenging. Herein, an Ni-metal−organic framework (MOF) was self-assembled on GO nanosheets via the solvothermal method and was subsequently etched into the Ni(OH) 2 -GO composite electrode material through a gentle hydrolysis strategy. The GO support enables fast electron transport within the composite material, and the nickel hydroxide growth on GO nanosheets can prevent their aggregation, guaranteeing rapid ion migration. The improved Ni(OH) 2 -GO battery-type electrode features outstanding stability (capacity retention of 108% at 8000 cycles) and a considerable specific capacity (SC) of 1007.5 C g −1 at a current density of 0.5 A g −1 . Compared with MOF-derived Ni(OH) 2 obtained through hydrolysis, Ni(OH) 2 -GO only contains 7.41% wt GO, while its SC is almost 50% higher. An asymmetric supercapacitor has an energy density of 65.22 W h kg −1 and a power density of 395.27 W kg −1 utilizing p-phenylenediamine-functional reduced GO as the negative electrode, and it can maintain 73.08% capacity during 8000 cycles at a current density of 5 A g −1 .

Synthesis, Properties, and Applications of Metal Organic Frameworks Supported on Graphene Oxide

“…Li et al [140] successfully produced Ni(OH) 2 -GO electrode materials using a two-step synthesis process. The numerous functional groups on GO nanosheets aid in the nucleation and growth of Ni-MOFs.…”

“…The Ni(OH) 2 -GO electrode material exhibits exceptional stability (the capacity retention rate after 8000 cycles is 108%) and a high SC of 1007.5 C g −1 . The ASC device can operate with excellent stability at a power density of 393.29 W kg −1 and has an energy density of 65.22 Wh kg −1 when PPD-rGO is used as the negative electrode [140].…”

Multicomponent Metal Oxide- and Metal Hydroxide-Based Electrocatalysts for Alkaline Water Splitting

“…To overcome these limitations, various strategies have been applied to oxide/hydroxide-based catalysts such as heterostructure engineering, doping, and anchoring single atoms. Through these approaches, the number of active sites where the reaction occurs increases, and the intrinsic conductivity of the catalysts can be improved [73][74][75][76][77][78][79][80][81][82]. The representative strategies to accomplish the advanced oxide/hydroxide-based catalysts are proposed in Figure 2.…”

Electrode Materials, Structural Design, and Storage Mechanisms in Hybrid Supercapacitors

“…Fabricating a composite by incorporating highly conductive graphene nanosheets into Ni(OH) 2 materials is considered as the most effective strategy to enhance the intrinsic properties of Ni(OH) 2 . Li et al [ 52 ] reported a novel Ni(OH) 2 /rGO hybrid material, which not only exhibited a high specific capacity (1007.5 C g −1 at 0.5 A g −1 ), but also showed good life cycle stability (108% capacitance retention after 8000 cycles), revealing its good performance by incorporating rGO. Guo et al [ 53 ] prepared a Ni(OH) 2 /rGO hybrid electrode and found a high specific capacity (1388 C g −1 at 2 A g −1 ) and remarkable rate capability (785 C g −1 at 50 A g −1 ).…”