We characterize the time evolution (≤120 s) of atmospheric-pressure plasma jet (APPJ)-synthesized Pt-SnOx catalysts. A mixture precursor solution consisting of chloroplatinic acid and tin(II) chloride is spin-coated on fluorine-doped tin oxide (FTO) glass substrates, following which APPJ is used for converting the spin-coated precursors. X-ray photoelectron spectroscopy (XPS) indicates the conversion of a large portion of metallic Pt and a small portion of metallic Sn (most Sn is in oxidation states) from the precursors with 120 s APPJ processing. The dye-sensitized solar cell (DSSC) efficiency with APPJ-synthesized Pt-SnOx CEs is improved greatly with only 5 s of APPJ processing. Electrochemical impedance spectroscopy (EIS) and Tafel experiments confirm the catalytic activities of Pt-SnOx catalysts. The DSSC performance can be improved with a short APPJ processing time, suggesting that a DC-pulse nitrogen APPJ can be an efficient tool for rapidly synthesizing catalytic Pt-SnOx counter electrodes (CEs) for DSSCs.
A direct current-pulse nitrogen atmospheric-pressure plasma jet (APPJ) is used to convert Pt-NiOx nanocompounds from liquid precursor films consisting of a mixture of chloroplatinic acid and nickel acetate. The Pt-NiOx nanoparticles are well-distributed on the fluorine-doped tin oxide (FTO) glass substrates. X-ray photoelectron spectroscopy results indicate that the reaction product mainly contains metallic Pt and oxidized Ni. Electrochemical impedance spectroscopy and Tafel experiments reveal an improvement in electrochemical catalytic effects. The APPJ-processed Pt-NiOx nanocompounds on FTO glass substrates are used as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). J − V curves indicate that DSSCs with 5-s APPJ-processed Pt-NiOx CEs showed significantly improved performance. The sample properties become stable after ∼45 s of APPJ calcination. Precursor solutions with three different mole ratios of chloroplatinic acid and nickel acetate are investigated. With the addition of an adequate amount of oxidized nickel, the transfer charge current density and electrochemical catalytic effects are enhanced.
We investigate the ultrashort (< 1 min) calcination process for Pt-SnO x catalysts converted from a mixture solution of chloroplatinic acid and tin(II) chloride in air. An electric furnace is used to test the ultrashort calcination of Pt-SnO x catalysts used as counter electrodes (CEs) of DSSCs. By using a conventional electric furnace instead of an atmospheric pressure plasma jet (Metals 8:690, 2018), the effect of reactive plasma species can be ruled out, and only the bare thermal effect is considered in this study. Scanning electron microscopy reveals that Pt-SnO x nanoparticles are well-distributed on the substrates. X-ray photoelectron spectroscopy indicates the conversion of a large amount of metallic Pt and oxidized Sn. No metallic Pt is observed with 5-s calcination; however, ~ 74% Pt is converted into metallic Pt with 15-s calcination. Further increasing the calcination time does not increase the conversion rate of metallic Pt. By contrast, metallic Sn shows its maximum conversion rate of ~ 18% with 30-s calcination. Further increasing the calcination time to 30 min reduces the metallic Sn content to ~ 6%, possibly owing to Sn re-oxidation. When applying Pt-SnO x catalysts to CEs of DSSCs, the efficiency greatly increases as the calcination time increases from 15 to 30 s. The efficiency remains relatively unchanged for calcination time of 60 s to 30 min. The efficiencies of DSSCs with a Pt-SnO x CE calcined at longer processing times (≥ 60 s) are comparable to those of DSSCs with conventional Pt CEs.
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