Graphene Oxide (GO) is two dimensional material that has been widely studied as an electrode material for supercapasitor. We prepared thin films of GO on metal oxide substrate of indium tin oxide (ITO) and metal substrate of Copper (Cu) using electrochemical deposition technique from 0.5 mg/ml GO dispersed in water. ITO-GO film was prepared using voltage range of -1.6 V to 0 V (ITO) and Cu-GO film was prepared using voltage range of 0 V to 1 V at scan rate of 50 mV/s. Both samples were characterized using Cyclic Voltammetry (CV) measurements in 1 M KCl electrolyte at varied scan speed with platinum (Pt) as counter electrode and Ag/AgCl as reference electrode. We compare energy storage characteristics of ITO-GO and Cu-GO using cyclic voltammogram data. It is found that GO deposited in metal substrate of Cu has higer energy density compare to that deposited in metal oxide substrate of ITO.

Dyes disposal from the industrial sector into the environment greatly affects the quality of the water. Among various technologies of removing dye pollutants from wastewater, adsorption is one of the most effective and favorable methods. Graphene oxides (GO) has been applied to remove dye pollutants in solution since it has a lot of oxygen-containing groups that can attract and bind pollutants. We study the effect of stirring time on MB adsorption onto GO surfaces. We mixed MB solution with GO dispersion and stirred at varied stirring times. The mixture was kept at room temperature to allow precipitation of the GO-MB mixture and then filtered to separate the precipitate from the residual MB solution. A reduction of MB concentration in the solution was measured using spectroscopy. The experimental results show that MB was adsorbed very fast onto GO surfaces in the first minutes and then the rate of the reduction of MB concentration becomes slower. After the stirring for 60 minutes, almost there is no significant change of the MB concentration that indicated a limit of adsorption capacity of GO.

Reduced graphene oxide (RGO) is promising candidate to be used as an active material of super capacitor electrodes. Graphene oxide (GO) is mostly used as a precursor, therefore it is needed to remove its oxygen containing functional groups. Generally, the RGO films are obtained from Graphene Oxide (GO) films which are then treated using thermal reduction or photo reduction process. We developed a spraying coating method that called as UV oven spraying by combining spraying coating method and photo reduction process. By this deposition method, we can obtain RGO films directly from the GO precursor since deposition and photo reduction steps are taken place at the same time. Level of oxygen removal of the obtained RGO film depends on irradiation intensity and length of irradiation. In this work, we report the effect of varied length of irradiation time on the RGO optical characteristics. We prepared multilayer of RGO films using UV oven spraying technique on quartz substrates from 0.5 mg/ml commercial GO dispersion (Graphenea) with varied the UV irradiation time. We used 125-Watt mercury lamp that was set at distance of 30 cm from substrates. We examined the effect of varied of length of irradiation time on its optical characteristics using UV-Vis Spectroscopy. Level of reduction by provided irradiation time was examined using SEM/EDS measurement.

Abstrak. Reduced Graphene Oxide (RGO) memiliki potensi aplikasi sebagai elektroda superkapasitor. Dalam penelitian ini dikaji karakteristik charge-discharge dari sistem superkapasitor RGO yang menggunakan larutan KCl sebagai elektrolit. Film tipis Graphene Oxide (GO) dibuat dengan teknik solution casting di atas substrat glass/ITO dari dispersi GO dalam akuades dengan konsentrasi 1 mg/ml. Untuk mendapatkan film RGO maka film GO yang telah dibuat direduksi secara termal di atas hotplate pada suhu 200C selama 1 jam untuk mengurangi kadar oksigen pada film tersebut. Model superkapasitor terdiri dari pasangan film RGO/ITO sebagai elektroda, serta larutan I M KCl sebagai elektrolit. Untuk melihat karakteristik dari model divais superkapasitor tersebut dilakukan pengujian charge-discharge pada berbagai macam arus discharge. Kata kunci : oksida grafena tereduksi, reduksi termal, model superkapasitor, chargedischargeAbstract. Reduced Graphene Oxide (RGO) has potential application as a supercapacitor electrode. We studied charge-discharge characteristic of RGO supercapacitor using KCl solution as electrolyte. Thin film of Graphene Oxide (GO) was prepared using solution casting technique on glass/ITO substrate from 1 mg/ml GO dispersed in water. RGO thin film was obtained from GO film that was thermally reduced on a hotplate at temperature of 200C for 1 hour to remove its oxygen contained. Supercapacitor device model was consist of pair of RGO/ITO films as electrodes, and 1 M KCl solution as electrolyte. In order to measure characteristic of the supercapacitor device model, we performed chargedischarge measurements at varied discharge current.

Reduced Graphene Oxide (rGO) is a promising material as an active electrodes material for supercapacitors. However, in its application, rGO can only store electrostatic charges so there is no electron transfer between surface of the electrode and electrolyte. In order to improve electrode performance, rGO can be composite with conductive polymers such Polyaniline (PANi). It was reported that rGO-PANi composite can increase conductivity of rGO and support pseudocapacitance of the material so the electron transfer can be carried out actively through reduction-oxidation (redox) reactions. In this work we study preparation of rGO-PANI composite using UV oven spraying method. Thin layers of rGO-PANi composite were prepared from mixture of 0.5 mg/ml GO dispersion (Graphenia) and PANi-HCl solution with a ratio of 1:1. PANi-HCl solution were prepared from PANi Emeraldine Base and 1 M HCl with mole ratio of 1:2. The samples were spray coated onto quartz substrates under photo-irradiation using UV Oven Spraying apparatus. In order to obtain a proper thickness for electrode application we varied deposition repetition. The optical characteristics of the rGO-PANi composites were measured using UV-Vis Spectroscopy. The results were compared with the optical spectra of rGO and PANi, respectively. Acknowledgement This work was funded by Hibah Kemenristek Dikti Indonesia, contract no: 1827/UN6.3.1/LT/2020 date 12 May 2020.