A New Si/TiO₂/Pt p-n Junction Semiconductor to Demonstrate Photoelectrochemical CO₂ Conversion

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• 作者：Thaí ; s Tasso Guaraldo^a ; ^b ; ¹ ; Juliana Ferreira de Brito^a ; ¹ ; ^{jfbrito@ymail.com" class="auth_mail" title="E-mail the corresponding author} ; David Wood^b ; Maria Valnice Boldrin Zanoni^a
• 关键词：Si/TiO2/Pt ; heterojunction ; CO2 reduction ; photoelectrocatalysis
• 刊名：Electrochimica Acta
• 出版年：2015
• 出版时间：10 December 2015
• 年：2015
• 卷：185
• 期：Complete
• 页码：117-124
• 全文大小：1630 K

文摘

This work presents a new Si/TiO₂/Pt p-n junction semiconductor prepared by sputtering, chemical vapor deposition (CVD), photolithography and lift-off techniques. XRD, EDS, FE-SEM, diffuse reflectance (DRS) and photocurrent vs potential curves had been used for semiconductor characterization. The material was designed for high porosity and uniformity of both TiO₂ and Pt deposits; both TiO₂ anatase phase formation and Pt presence were confirmed. This semiconductor has a characteristic of high light absorption in the ultraviolet and visible regions. A good photocurrent response for the cathodic region was obtained in a CO₂ saturated solution (−1.0 mA under −0.8 V and UV–vis light), confirming electron-hole pair formation and CO₂ electron scavenging. A small Si/TiO₂/Pt electrode (1 × 1 cm) was employed in photoelectrocatalytic CO₂ reduction, forming methanol (0.88 mmol L⁻¹), ethanol (2.60 mmol L⁻¹) and acetone (0.049 mmol L⁻¹) as products reaching a Faradaic efficiency of 96.5%. These results had been obtained under the following optimal experimental conditions: 0.1 mol L⁻¹ NaHCO_3, pH 8 saturated with CO₂, 125 W UV–vis irradiation (from 250 to 600 nm) and −0.8 V applied potential. Suitable charge transfer mechanisms in the electrode surface, and products formation after CO₂ reduction, are proposed.