Microwave exfoliated graphene-based materials for flexible solid-state supercapacitor

Herein, we report the simultaneous exfoliation and reduction of graphene oxide (GO) and graphene nanoplatelets (GNPs) by rapid microwave irradiation, to overcome the hurdles of their low electrical conductivity and tendency to restack, and realize their full potential as supercapacitor electrode materials. After microwave treatment, the ID/IG value of the microwaved GO (MW-GO) increased by 0.11, whereas the I2D/IG value of the microwaved GNPs (MW-GNPs) decreased by 0.48, revealing that the graphene-based materials were reduced and exfoliated as observed in the Raman spectra. Morphological studies revealed a porous structure of MW-GO and loose stacked layers of MW-GNPs, which showed the exfoliation of the graphene-based materials. A supercapacitor device was constructed using a mixture of MW-GO, MW-GNPs, and polypyrrole and yielded a specific capacitance value of 137.2 F g−1 with a cycling stability of 89.8% after 1000 charge/discharge cycles. The electrochemical performance of the device remains unchanged when bent continuously at 180° because the cyclic voltammetry and galvanostatic charge/discharge curves remained the same after 50 bending repetitions. Therefore, the simultaneous reduction and exfoliation of these graphene-based materials by rapid microwaves provides a promising route for the scalable and cost-effective preparation of supercapacitor electrode materials

Microwave exfoliated graphene-based materials for flexible solid-state supercapacitor

Herein, we report the simultaneous exfoliation and reduction of graphene oxide (GO) and graphene nanoplatelets (GNPs) by rapid microwave irradiation, to overcome the hurdles of their low electrical conductivity and tendency to restack, and realize their full potential as supercapacitor electrode materials. After microwave treatment, the ID/IG value of the microwaved GO (MW-GO) increased by 0.11, whereas the I2D/IG value of the microwaved GNPs (MW-GNPs) decreased by 0.48, revealing that the graphene-based materials were reduced and exfoliated as observed in the Raman spectra. Morphological studies revealed a porous structure of MW-GO and loose stacked layers of MW-GNPs, which showed the exfoliation of the graphene-based materials. A supercapacitor device was constructed using a mixture of MW-GO, MW-GNPs, and polypyrrole and yielded a specific capacitance value of 137.2 F g−1 with a cycling stability of 89.8% after 1000 charge/discharge cycles. The electrochemical performance of the device remains unchanged when bent continuously at 180° because the cyclic voltammetry and galvanostatic charge/discharge curves remained the same after 50 bending repetitions. Therefore, the simultaneous reduction and exfoliation of these graphene-based materials by rapid microwaves provides a promising route for the scalable and cost-effective preparation of supercapacitor electrode materials

An effective metal-organic framework-based electrochemical non-enzymatic glucose sensor

Herein, we report a non-enzymatic glucose sensor based on a metal-organic framework (MOF) as alternative approach for long-term glucose monitoring. Specifically, nickel-based MOFs were solvothermally synthesized using either 2-amino-1,4-benzenedicarboxylic acid (BDC-NH2) or 2-hydroxy-1,4-benzenedicarboxylic acid (H2BDC-OH), both of which were characterized by different physicochemical techniques. The electrochemical performance of both electrodes towards glucose sensing was investigated and Ni-BDC-NH2 exhibited a significantly better electrocatalytic behaviour towards oxidation of glucose than bare Ni-BDC or Ni-BDC-OH in an alkaline media. This was attributed to a favourable multi-layered sheet-like structure that allowed diffusion for entrapment of glucose and the incorporation of –NH2 functional groups attached to the BDC linker which, were responsible for electrochemical adsorption of glucose molecules. Ni-BDC-NH2 displayed a lower detection limit (3.82 μM), higher stability (>180 days), and remarkable sensitivity (308 μA mM−1 cm−2). Additionally, a molecular sieve effect for Ni-BDC-NH2 led to a noteworthy anti-interference ability and the sensor displays a fast response time of 5.4 s towards glucose detection. These results indicate that the as-synthesized non-enzymatic glucose sensor operates with a longer lifetime and is viable for use as an intensive monitoring system