Ethyl cellulose

A paste based on oxide powder (dried at 60 °C) and α-terpineol (>97%, Acros Organics, Geel, Belgium) solution of ethylcellulose (48.0–49.5% (w/w) ethoxyl basis, Sigma Aldrich, St. Louis, MO, USA) was prepared in order to serve as functional ink. Microextrusion printing of oxide film on the surface of a special Pt/Al₂O₃/Pt chip was carried out using a 3D positioning system and pneumatic doser (pressure above ink was 1.1 atm), equipped with dispenser and G27-caliber needle (inner diameter 210 µm). The speed of dispenser movement above the substrate surface was 1 mm/s, the time interval between impulses of paste dosing, as well as their duration, was 0.5 s. The chip consisted of an α-Al₂O₃ substrate (R_a = 100 nm) with platinum interdigital electrodes on the face side and a platinum meander microheater on the reverse. After printing was finished, the film was dried at 25 °C and then calcined in air at 300 °C for 1 h to remove organic components and facilitate the formation of V₂O₅ film.

Chemicals ((NH₄)₂Cr₂O₇, Cr₂O₃, AgNO₃, Zn(NO₃)₂, α-terpineol, ethyl cellulose and others) were obtained from Sigma-Aldrich (Saint Louis, MO, USA) unless noted otherwise. Expanded graphite EPGM for preparation of the CPE and SPE were purchased from Graphite Tyn Ltd. (Tyn nad Vltavou, Czech Republic).
In the study, high-purity deionized water (Milli-Q Millipore 18.2 MΩ/cm, Bedford, MA, USA) was used. Chromium(III) oxide for modification of the paste electrode was prepared by the thermal decomposition of ammonium dichromate. The prepared chromium(III) oxide was washed 9 times with water to prevent impurities caused mainly by trace contamination or residual dichromate.

Cadmium acetate, selenium, zinc acetate, hexamethyldisilathiane ((TMS)₂S), trioctylphosphin oxide (TOPO), trioctylphosphine (TOP), ethyl cellulose (EC), mercaptopropionic acid (MPA), 4-dimethylamino pyridine (DMAP), 1-hexadecylamine, stearic acid, 3-glycidoxypropyl trimethoxysilane (GPTMS), 3-aminopropyltrimethoxysilane (APTMS), aminofluorescein (AF), melamine, paraformaldehyde, horseradish peroxidase (HRP), hydrogen peroxide, and sodium α-ketobutyrate were purchased from Sigma-Aldrich Chemical Co. (Seoul, Korea). N,N-Dimethylformamide (DMF), dimethylsulfoxide (DMSO), methanol, ethanol, and chloroform were obtained from Honeywell International Inc. Burdick & Jackson (Ulsan, Korea). Other chemicals such as hydrochloric acid, sodium hydroxide, sodium phosphate (mono- and dibasic), sodium chloride, and phosphate buffer were of analytical grade and used without further purification.

PCL Mn  =  80,000 was purchased from Sigma-Aldrich (Tokyo, Japan), ethyl cellulose from Sigma-Aldrich Chemie GmbH (St Louis, MI, USA), Norethindrone acetate from Leap Chem (Hong Kong, China) and sodium hydroxide pellets from Merck Chemicals (Modderfontein, South Africa). NIH/3T3 mouse fibroblast cells (ATCC CRL-1658) were obtained from the ATCC (American Type Culture Collection, Manassas, VA, USA), Dulbecco’s Modified Eagle Medium (DMEM) from Life Technologies Limited “Gibco” (Paisley, UK), Fetal bovine serum from PAN Biotech (Aidenbach, Germany), and MTT solution and solubilizing buffer from Roche Diagnostic GmbH (Mannheim, Germany). All other chemicals were of analytical grade and used without further purification.

All the dyes were synthesized according to the previously published procedures [20 (link)]. The dyes purity was determined to be at least 97% by HPLC. All the other chemicals were of sufficient grade and used without further purification. Acetic acid, acetone, and anhydrous EtOH were obtained from Avantor Performance Materials (Gliwice, Poland), anhydrous acetonitrile and HPLC grade DCM from Sigma Aldrich (St. Louis, MO, USA), and anhydrous THF from Acros Organics (Fair Lawn, NJ, USA). 1-methyl-3-propylimidazolium iodide, lithium iodide, iodine, 4-tert-butylpyridine, titanium(IV) chloride, hexachloroplatinic acid, α-terpineol, ethylcellulose, and CDCA were received from Sigma Aldrich, while tetrabutylammonium hexafluorophosphate was from TCI Chemicals (Tokyo, Japan). TCO22-7 FTO glass substrates were obtained from Solaronix, P25 Aeroxide titania nanopowder from Evonik (Essen, Germany).

The Mae Moh Power Plant in Lampang Province of Northern Thailand was the source of the fly ash powder used in the current study. It was heated at 80 °C for 24 h. PEDOT:PSS (Sigma Aldrich) was dissolved in distilled water in a mass/volume ratio of 1 to 1. Fly ash was added and mixed in various ratios of fly ash to PEDOT:PSS of 1:5, 2:5, 3:5, and 4:5 g/mL. These samples are referred to as FP-1:5, FP-2:5, FP-3:5 and FP-4:5, respectively. The FP mixtures were stirred for 15 min. Fluorine-doped tin oxide glass (FTO, 15/sq, Solaronix) was thoroughly cleaned with soapy water, followed by 30 min of ultrasonication with deionized water and ethanol. After drying, FP films were prepared and applied to FTO glass over a 0.5 cm² area masked with tape using a doctor blade (Fig. 1). Then, the obtained FP films were heated at 80 °C for 6 h. Using Pt as a CE standard, Pt electrode was prepared by mixing 3 mM tetraammineplatinum(II) chloride hydrate (98%, Sigma Aldrich) and 0.2 g ethyl cellulose (Sigma Aldrich) in isopropyl alcohol (Sigma Aldrich) and spin-coated at 500 rpm for 30 s and 1500 rpm for 30 s followed by drying at 80 °C onto FTO glass for three cycles before sintering at 500 °C for 1 h under an air atmosphere.Figure 1

Schematic of the fly ash counter electrode and DSSC J-V curves.