Synthesize of rGO from coal (sub-bituminous) as a counter-electrode on dye-sensitized solar cells

Abstract

Abstract In the quest for a replacement for platinum as catalytic material in DSSC’s counter electrode (CE), this research aims to extract reduced graphene oxide (rGO) from coal. The coal used was a sub-bituminous type originated from Kolaka Timur, which extracted to rGO with modified Hummer methods. The resulting rGO was characterized by Energy Dispersive X-Ray Spectroscopy (EDS), FTIR, XRD, and LCR meter, to investigate the atomic composition, chemical bonds, crystal structure, and conductivity. For CE fabrication, rGO was mixed with ethyl cellulose (EC) and dissolved in terpineol with a ratio of 100:10, 100:20, 100:50, 100:70, and 100:100 in weight. The structure of the fabricated solar cell was FTO/TiO2/Dye/Electrolyte/rGO/FTO. From the EDS result, we identified the elements of C and O that was the main constituent for rGO, with the highest C/O ratio was 0.81. From FTIR spectra, it was found that the rGO still contain impurities originated from quartz, kaolinite and illite mineral. From rGO 4 XRD characterization, the rGO peak was identified at a 2θ position of 23.9° with a crystallite size of 47.5 nm. The obtained conductivity for rGO in this research was 2.18 x 10−1 S/cm. From photovoltaic characteristic measurement, the highest overall conversion efficiency was 0.046% for rGO:EC of 100:70. The efficiency of the DSSC cells in this research was noticeably low due to the quality of the resulting rGO that was marked by small C/O ratio and the existence of impurity minerals as indicated in the FTIR and XRD data.