MNO2 NANOCLUSTER-DECORATED PANI/RGO AS PLATINA- FREE COUNTER ELECTRODES ON DYE- SENSITIZED SOLAR CELL

• Main Author: Fauziah, Nenden
• Format: Dissertations
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/80638
• Institution: Institut Teknologi Bandung

Dye-sensitized solar cells have four main components: working electrode, dye, electrolyte, and counter electrode. The counter electrode must have high electrical conductivity and electrolyte-reducing power to maintain charge flow in the system. The counter electrode performs well, and the most widely used is conductive glass coated with platinum metal (Pt). The use of Pt causes the counter electrode to be the most expensive part of a DSSC, so developing a Pt-free counter electrode is crucial. Pt can be replaced with other materials such as metals and metal alloys, carbon materials, transition metal compounds, composites, and conductive polymers. Polyaniline (PANI) is considered the most promising conductive polymer substitute for Pt due to its excellent reaction rate of PANI towards the ?????/????? redox couple. PANI, synthesized by the pulsed electropolymerization method, was successfully deposited on the surface of synthetic graphite. FTIR-ATR analysis and Raman spectroscopy confirmed PANI as PANI emeraldine salt (PANI ES). SEM analysis confirms that the morphology of the PANI is nanofiber with a larger fiber diameter as the load variation increases. PANI 10% load variation gives an average diameter of x? = 80 nm and the lowest film thickness (11.56 ?m), lowest RCT (59.00 ?), lowest RS (40.06 ?), highest VOC ( 0.688 V), and the highest JSC (9.066 mA cm- 2), which produces the highest performance (??= 2.402%). The electropolymerization method is environmentally friendly and produces PANI counter electrodes with good performance, but its application in counter electrodes based on PANI composites, such as PANI-Graphene, is tricky. Graphene has various excellent properties, contributing to its wide potential applications. Electrochemically exfoliated graphene (EEG) is a graphene-like material synthesized via electrochemical methods, requiring a shorter synthesis time and much less chemical waste than the Hummers method. Ultrasonication modification of EEG is predicted to increase the structure of defects, dispersion capability, and performance of EEG as a counter-electrode material in DSSC. FTIR-ATR, XRD, and Raman spectroscopy confirmed that the EEG material was rGO. SEM-EDS analysis observed that all EEGs have thick layer morphology. The results of the dispersion study showed that repeated ultrasonication improved the dispersion ability of the EEG material. In addition, Raman spectrum analysis confirmed an increase in structural defects as the number of sonication repetitions increased, which is thought to have an impact on increasing the electrocatalytic activity of the EEG material. The EEG with 6 repetitions of sonication (EEG_6) gave the highest performance as a CE in DSSC with 0.890 % efficiency, while the reduced graphene oxide (rGO) with the Hummers method is 0.714%. The counter electrode of the mixed material of polyaniline (conventional method), graphite, and EEG_6 (PG_EEG_6) provides an efficiency of 2.493%, while the Pt counter electrode (?= 1.626 %), as a significant impact of the number of structural defects in the EEG_6 material. The strong electrostatic interaction between the graphene sheets can cause re- stacking of the EEG sheets. Besides increasing structural defects, the presence of MnO2 in EEG also produces a steric hindrance that prevents the re-stacking of graphene sheets. MnO2 is an eco-friendly transition metal oxide with a fast, reversible redox surface reaction. Unfortunately, MnO2 has poor electrical conductivity. The EEG-MnO2 composite is expected to produce a material with good conductivity and electrocatalytic activity. The performance of the EEG_Mn counter-sample electrode (??= 1.87 %) is comparable to that of the platinum electrode (??= 1.84 %). However, the performance of the EEG_Mn sample, which was annealed at 450°C for 2 hours (EEG_Mn_450), only provided an efficiency of 1.78%. Making the PANI_EEG_Mn composite is expected to have an impact on improving EEG_Mn performance. However, the test results on the PANI_EEG_Mn counter electrode showed a decrease in performance with an efficiency of 1.56%. The mixture of PANI and EEG_Mn (PANI/EEG_Mn) provides an efficiency of 2.10%. More significant results were shown by the mixed PANI and EEG_Mn_450 counter electrode (PANI/EEG_Mn_450) with an efficiency of 2.34%. The performance of the PANI/EEG_Mn_450 counter electrode was 27.2% better than the performance of the Platina counter electrode. The characterization results show that the EEG_Mn_450 material is rGO-MnO2 material, so PANI/EEG_Mn_450 is PANI/rGO-MnO2 material. The use of sonication-modified EEG material for making PANI/rGO-MnO2, which is applied as a counter electrode material in dye-sensitized solar cells, has never been done. The PANI/rGO-MnO2 composite has excellent potential for use as a counter electrode in platinum-free dye-sensitized solar cells. The results of this research are expected to contribute to the development of renewable energy sources that are environmentally friendly to address energy and environmental problems, especially in Indonesia.