We attempted to deposit platinum (Pt) onto a tungsten trioxide (WO3) thin film by the photoreduction of Pt4+ (Pt-WO3). Pt on WO3 was oxidized (PtOx) by calcining Pt-WO3 in air to form PtOx-WO3. An n-type anomalous photo-thermoelectric (photo-TE) effect was confirmed for Pt-HyWO3-x, a protonated WO3, after the gaschromic (GC) reaction of Pt-WO3. That is, both the electrical conductivity (sigma(photo)) and the absolute value of the Seebeck coefficient (S-photo) increased under visible-light irradiation. After stopping the irradiation, both values decreased (sigma and S). In contrast, an n-type normal photo-TE effect was observed for PtOx-HyWO3-x after the GC reaction of PtOx-WO3, in which sigma(photo) and the absolute value of S-photo increased and decreased, respectively, under visible-light irradiation, and vice versa after stopping the irradiation. These findings indicate that Pt was responsible for the generation of the anomalous photo-TE effect, probably due to the electron accumulation capability of Pt, to which electrons were transferred from the conduction band of HyWO3-x. In contrast, electrons could not energetically transfer from HyWO3-x to PtO2, which was included in PtOx particles at the surface. Therefore, PtOx was not responsible for the anomalous photo-TE effect, and PtOx-HyWO3-x behaved like bare HyWO3-x, indicating its normal photo-TE effect. nbsp; nbsp;Published under an exclusive license by AIP Publishing.
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