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

Guaraldo, T.T.; de Brito, J.F.; Wood, D.; Boldrin Zanoni, M.V.

Abstract

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 NaHCO3, 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.

Citation

Guaraldo, T., de Brito, J., Wood, D., & Boldrin Zanoni, M. (2015). A New Si/TiO2/Pt p-n Junction Semiconductor to Demonstrate Photoelectrochemical CO2 Conversion. Electrochimica Acta, 185, 117-124. https://doi.org/10.1016/j.electacta.2015.10.077

• Journal Article Type: Article
• Acceptance Date: Oct 16, 2015
• Online Publication Date: Nov 4, 2015
• Publication Date: Dec 10, 2015
• Deposit Date: Jan 4, 2016
• Publicly Available Date: Nov 4, 2016
• Journal: Electrochimica Acta
• Print ISSN: 0013-4686
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 185
• Pages: 117-124
• DOI: https://doi.org/10.1016/j.electacta.2015.10.077
• Public URL: https://durham-repository.worktribe.com/output/1393088