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Journal : JFA (Jurnal Fisika dan Aplikasinya)

Study of the formation of amorphous carbon and rGO-like phases from palmyra sugar by variation of calcination temperature Fahmi Astuti; Novita Sari; Vera Laviara Maghfirohtuzzoimah; Retno Asih; Malik Anjelh Baqiya; Darminto Darminto
Jurnal Fisika dan Aplikasinya Vol 16, No 2 (2020)
Publisher : Lembaga Penelitian dan Pengabdian Kepada Masyarakat, LPPM-ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24604682.v16i2.6706

Abstract

We have processed biomass from palmyra sugar to produce allotrope carbon by heating process with the variation of calcination temperature. The formation of amorphous carbon (a-C) was confirmed from the XRD result heated at 400°C with the observation of the peak at the position of ~24o. By increasing the temperature at 700°C, the presence of two peaks at 24o and 43o were observed, indicating the formation of rGO-like phase. The functional groups detected by FTIR spectra consist of C=C, C-O, C=O, C-H and O-H. The result of conductivity measurement exhibits that the material can be classified as semiconducting materials.
Physical Properties Comparison of rGO-like phase prepared from Coconut Shell and the Commercial Product Retno Asih; Maya Mahirotul Septya; Erik Bhekti Yutomo; Fahmi Astuti; Malik Anjelh Baqiya; Darminto Darminto
Jurnal Fisika dan Aplikasinya Vol 16, No 2 (2020)
Publisher : Lembaga Penelitian dan Pengabdian Kepada Masyarakat, LPPM-ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24604682.v16i2.6712

Abstract

Physical properties of reduced graphene oxide (rGO) prepared from two different raw materials, namely coconut shell (rGO-s) and graphite mineral (rGO-c, produced by Graphenea Inc.), have been investigated. While both samples have the same density of about 1.9 g/cm3, rGO-c has more porous of about 1.3 cc/g with diameter of 10.8 nm compared to rGO-s which has 0.2 cc/g porous with diameter of 2.4 nm. Specific surface area in rGO-c was also obtained much larger than that of rGO-s. rGO-c and rGO-s have specific surface area of ~298 m2/g and ~475 m2/g, respectively. Examinations on particle size and surface morphology show that rGO-c has homogenous particles which consist of transparent thin sheets, while rGO-s has rather heterogenous particles that look like dens stacked sheets. The presence of C and O was confirmed at the observed morphology. The difference in physical features were then found to influence the obtained electrical conductivity of the samples. rGO-c has higher conductivity than rGO-s. Estimation on gap energy (Eg) indicates that rGO-c and rGO-s have Eg in the range of semiconducting materials. The study provides a better understanding on physical properties of coconut shell-derived rGO to further revise synthesis method to improve quality of the obtained rGO.
Determining the Deposition Rate of Semiconducting Intrinsic Layer Prepared by Nanospray Method Aulia Anisa Firdaus; Endhah Purwandari; Retno Asih; Ahmad Sholih; Darminto Darminto
Jurnal Fisika dan Aplikasinya Vol 19, No 2 (2023)
Publisher : Lembaga Penelitian dan Pengabdian Kepada Masyarakat, LPPM-ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24604682.v19i2.16559

Abstract

Amorphous carbon (a-C) film provides potential ability as an i-type layer in semiconductor material for photovoltaic purposes due to its tunable properties. Here, we investigate how to get the deposition rate estimation of the thickness and homogenous surface of a-C film as an i-type in solar cell applications. The a-C was prepared from palmyra liquid sugar using nebulizer as a nanospray method. The thick palmyra liquid sugar was carbonized at 250◦C for 2.5 hours then continued at 300◦C for 2 hours to obtain high-carbon charcoal. The thickness was examined using a SEM cross section, and the amorphous phase was measured using XRD. The amorphous characteristic of a-C is confirmed by broad peaks in XRD patterns. The thickness of a-C films was found to be thinner than in a previous study that used a similar materials and methods but different equipment in the deposition process. The average thickness of a-C films is in the range of 200 to 450 nm, followed by an increase in the deposition time of 5 to 25 s. By these value, the deposition rate estimation was obtained using extrapolation linier method from the SEM result around 11.62 nm/s. This result can be used as a reference to make various thicknesses for the i-layer in order to find the maximum thickness that gives high efficiency to amorphous carbon film.