Syngas production by electrocatalytic reduction of CO 2 using Ag-decorated TiO 2 nanotubes
M. A. Farkhondehfal (Istituto Italiano di Tecnologia)
S. Hernández (Politecnico di Torino)
M. Rattalino (Politecnico di Torino)
M. Makkee (TU Delft - ChemE/Catalysis Engineering)
A. Lamberti (Politecnico di Torino)
A. Chiodoni (Istituto Italiano di Tecnologia)
K. Bejtka (Istituto Italiano di Tecnologia)
A. Sacco (Istituto Italiano di Tecnologia)
F. C. Pirri (Istituto Italiano di Tecnologia, Politecnico di Torino)
N. Russo (Politecnico di Torino)
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Abstract
Huge efforts have been done in the last years on electrochemical and photoelectrochemical reduction of CO
2
to offer a sustainable route to recycle CO
2
. A promising route is to electrochemically reduce CO
2
into CO which, by combination with hydrogen, can be used as a feedstock to different added-value products or fuels. Herein, perpendicular oriented TiO
2
nanotubes (NTs) on the electrode plate were grown by anodic oxidation of titanium substrate and then decorated by a low loading of silver nanoparticles deposited by sputtering (i.e. Ag/TiO
2
NTs). Due to their quasi one-dimensional arrangement, TiO
2
NTs are able to provide higher surface area for Ag adhesion and superior electron transport properties than other Ti substrates (e.g. Ti foil and TiO
2
nanoparticles), as confirmed by electrochemical (CV, EIS, electrochemical active surface area) and chemical/morphological analysis (FESEM, TEM, EDS). These characteristics together with the role of the TiO
2
NTs to enhance the stability of CO
2
·-
intermediate formed due to titania redox couple (Ti
IV
/Ti
III
) lead to an improvement of the CO production in the Ag/TiO
2
NTs electrodes. Particular attention has been devoted to reduce the loading of noble metal in the electrode(14.5 %w/%w) and to increase the catalysts active surface area in order to decrease the required overpotential.