4.1 │ Materials
MCF was supplied as an aqueous colloidal suspension (2 wt%, Exilva) was
acquired from Borregaard (Norway). LiCl, SnO2 (average particle size of
1 µm), dimethylformamide (DMF, >99.9%), potassium
hydroxide (KOH, >99.5%), tin oxide (99%), and
dimethylacetamide (DMAc,>99.9%) were obtained from Sigma
Aldrich. All the chemicals were used as received without any further
purification. Distilled water was utilized throughout the experiment.
│Fabrication of MFC thin films
LiCl solution with a concentration of 10 wt% was first prepared by
stirring LiCl in DMAc at 80 °C. After cooling to room temperature, 1
wt% of MCF was then dispersed in DMAc for 30 min under stirring. Later,
MFC suspension was mixed with 10 wt% of LiCl/DMAc for 30 minutes. This
mixture was then vacuum filtrated using Whatman filter paper and MFC
thin films was dried overnight in oven at 60°C.
│ Preparation of hybrid tin oxide-cellulose nanocomposites
2 wt% of MFC was diluted into 0.2 wt% of MFC suspension using DMF
under stirring for 4 h at ambient temperature 16.
Different SnO2 loadings (4, 8, 12 wt%) were dispersed
in DMF separately and sonicated for 3 h before mixing with MFC
suspension (0.2 wt%) and stirred for another 1 h at 60 °C. Then,
SnO2-MFC mixtures were hydrothermally treated at 120°C. Dark brown
slurries were produced after 4 h.
│ Preparation and characterization of tin oxide-cellulose thin
films
MFC thin films were dip-coated with SnO2 -MFC nanocomposite slurries for
1 h. The coated thin films were dried in an oven at 80 °C overnight to
form flexible supercapacitors. After drying, they were rinsed with
distilled water and dried at 200 °C for 2 h. These thin films were
denoted as MFC-4SnO2, MFC-8SnO2, MFC-12SnO2, respectively. The surface
morphology of these thin films was study using scanning electron
microscopy (SEM, TM3000 Hitachi, Japan), while their chemical properties
was studied using X-ray diffraction (XRD, Bruker Advanced X-ray Solution
D8, Cu Kα radiation, l = 0.154 nm) and Fourier transform infrared
spectroscopy (FTIR, Nicolet iS10, Thermo Scientific, USA). The
electrochemical properties such cas yclic voltammetry (CV) and cyclic
stability were studied using µStat 300 BiPotentiostat electrochemical
workstation with the three-electrode system using 1 M of KOH solution as
the electrolyte solution. The electrochemical impedance spectroscopy
(EIS) data was collected using Metrohm Autolab potentiostat
electrochemical workstation.