The development of advanced electrode materials derived from biomass for the next generation of energy storage devices, such as supercapacitors with high specific energy and specific power coupled with a good cycle stability, is required to meet the high demand for electric vehicles and portable devices. In this study, sustainable binary vanadium pentoxide carbon-graphene foam composites (V
2
O
5
@C-R
2
HS/GF) were synthesized using a solvothermal method. The X-ray diffraction, Raman and FTIR techniques were used to study the structural properties of the composites (V
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O
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@C-R
2
HS/20 mg GF and V
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O
5
@C-R
2
HS/40 mg GF). The SEM micrographs displayed an accordion-like morphology resulting from the graphene foam-modified V
2
O
5
@C-R
2
HS composite. The V
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O
5
@C-R
2
HS, V
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O
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@C-R
2
HS/20 mg GF and V
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@C-R
2
HS/40 mg GF composites were evaluated in a three-electrode configuration using 6 M potassium hydroxide (KOH) as an aqueous electrolyte. Furthermore, a two-electrode device was carried out by fabricating an asymmetric device (V
2
O
5
@C-R
2
HS/GF//AC) where V
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O
5
@C-R
2
HS/20 mg GF was used as a positive electrode and activated carbon (AC) as a negative electrode at a cell voltage of 1.6 V in 6 M KOH. The V
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O
5
@C-R
2
HS/GF//AC showed a high specific energy and specific power values of 55 W h kg
−1
and 707 W kg
−1
, respectively, at a specific current of 1 A g
−1
. The asymmetric device presented a good stability test showing 99% capacity retention up to 10 000 cycles and was confirmed by the floating time up to 150 h with specific energy increasing 23.6% after the first 10 h.
This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)’.
Graphene photodetectors with asymmetric device structures on silicon chips
