SIAM: Science and Innovation of Advanced Materials

Study of Electrochromic Properties of PEDOT:PSS for Tunable Filter Optics with Lithium Salt Electrolyte

Nisakon Janthajam, Shu-Han Hsu, Sakoolkan Boonruang — Tue, 25 Jun 2024 00:00:00 +0700

Nowadays, conductive polymers based on poly(3,4-ethylenedioxythiophene), poly(styrene sulfonic acid), or PEDOT:PSS, have been employed as a flexible and transparent coating in various significant electronic applications. With the demand for electrochromic properties, such as in electronic displays, further research into its electrooptic properties is required, especially the systematic understanding to obtain the optimized switching. Our research investigates the electrooptic properties of the PEDOT:PSS film, particularly the refractive index changing under various applied biases. The electrochromic device is prepared in a simple fashion, and the electroactive layer of PEDOT:PSS thickness is defined via spin-coating between two indium tin oxide (ITO) substrates. To increase the switching properties of PEDOT:PSS, lithium perchlorate (LiClO₄) was prepared in acetonitrile, as the electrolyte in varied concentrations of 1.195 M, 1.5 M, and 2.0 M, respectively. A potential voltage of -4.0 V to 0.0 V is utilized to study the device's electrochromic properties with the step 5 mV/s continuously. Finally, the optical properties are characterized using the spectroscopy method based on real-time measurement of the transmission spectrum and transmission matrix calculations. The change in visible light absorption, transmission, and film color is recorded under a switching cycle that shows consistent behavior. This allows the further utilization of such a hybrid structure for possible tunable filter applications.

Keywords: Electrochromic, PEDOT:PSS, Optical, Lithium salt, Electrolyte

Biobased Activated Carbon from Palm Biomass Enhancing with Acid Treatment as Supercapacitor Electrode Material

Vituruch Goodwin, Thanathon Sesuk, Parinya Jitreewas — Tue, 25 Jun 2024 00:00:00 +0700

Current research on energy storage systems, batteries, and supercapacitor devices is aimed to enhance efficiency and improve environmental sustainability. Supercapacitors offer remarkable attributes such as high transient response and power density. Typically, supercapacitor electrode is made from highly porous carbon material, activated carbon. Commercial activated carbon could be produced from coal, peat, or coconut shell. This study focused on utilization of palm biomass, palm empty fruit bunch (EFB), as raw material to produce activated carbon electrode. The highly porous activated carbon from EFB was synthesized via a low-temperature hydrothermal process and chemical activation. The resulting EFB activated carbon demonstrates favorable characteristics in terms of elevated surface area and porosity. This research investigates the enhancement of activated carbon with acid treatment during hydrothermal process. Two types of acid, citric acid, and phosphoric acid, at different concentrations, were added to biomass. The acid-treated activated carbon from palm biomass was characterized for the specific surface area (BET), pore size distribution and pore volume using the N₂ adsorption/desorption technique. The acid-treated activated carbon was fabricated into carbon electrodes and assembled in a symmetrical supercapacitor with 1M H₂SO₄ as an electrolyte. The supercapacitor performance of acid-treated activated carbon was tested in a symmetrical Swagelok cell to assess specific capacitance using cyclic voltammetry and galvanostatic charge-discharge methods. The acid-treated activated carbon has higher specific capacitance than the activated carbon without acid treatment. This superior performance is attributed to the reduced internal resistance as revealed by the Electrochemical Impedance Spectroscopy (EIS) result. This is possibly due to the formation of micropores in the range of 0.6−0.7 nm which is a suitable pore size for ion transportation in H₂SO₄ electrolytes. This research has shown that biobased activated carbon from palm oil biomass with acid treatment has a high potential to be used as supercapacitor electrode material.

Keywords: Activated carbon, Palm biomass, Hydrothermal, Energy storage, Supercapacitor

Characterization and Visible Light-driven Photocatalytic Activity of SnS2/BiVO4 Nanocomposites Prepared by Sonochemical-based Process

Thanaphon Kansaard, Maneerat Songpanit, Wisanu Pecharapa — Tue, 06 Feb 2024 00:00:00 +0700

Bismuth vanadate (BiVO₄) is a good candidate photocatalyst material with good activity under visible light exposure. The photodecomposition performance of BiVO₄ could be enhanced by combining it with compatible tin sulfide (SnS₂). In this work, the synthesis of SnS₂/BiVO₄ nanocomposite was carried out by sonochemical process at room temperature with varying concentration ratios of SnS₂:BiVO₄ (0.05:1, 0.10:1, 0.15:1, 0.50:1 and 1:1). The crystallinity and morphological features of as-synthesized powders demonstrate the majority of BiVO₄ monoclinic phase accompanying minority of SnS₂ rhombohedral phase. FE-SEM micrograph shows the irregular shape with various particle sizes. The optical band gap of the composite inquired by Kubellka-Munk calculation is about 2.6 eV. The photocatalytic performance of as-synthesized nanocomposite was evaluated by means of decomposition of organic dye under visible light irradiation. The 0.05:1 ratio of the SnS₂/BiVO₄ sample exhibits superior photocatalytic activity with 60% decomposition of Rhodamine-B organic dye within 120 minutes.

Keywords: Bismuth vanadate, Tin sulfide, Nanocomposite, Photocatalyst material