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

Thaís Tasso Guaraldo, Juliana Ferreira De Brito, David Wood, Maria Valnice Boldrin Zanoni

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50 Citations (SciVal)


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.

Original languageEnglish
Pages (from-to)117-124
Number of pages8
JournalElectrochimica Acta
Early online date4 Nov 2015
Publication statusPublished - 10 Dec 2015

Bibliographical note

Funding Information:
The authors would like to acknowledge Dra. Angela Regina Araújo e Carolina Rabal Biasetto for helpful discussions, and Fapesp (2012/11141-1) and (2013/25343-8) for financial support.


  • CO reduction
  • heterojunction
  • photoelectrocatalysis
  • Si/TiO/Pt

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry


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