Document details

Description

Made available in DSpace on 2018-12-11T17:26:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-12-10

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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.

UNESP Chemistry Institute of Araraquara, R. Francisco Degni 55

School of Engineering and Computing Sciences Durham University, South Road

UNESP Chemistry Institute of Araraquara, R. Francisco Degni 55

FAPESP: 2012/11141-1

FAPESP: 2013/25343-8