Hybrid Sb2Se3/Molecular Catalyst Photocathodes for Carbon Dioxide Reduction
D. Alicia Garcia-Osorio a, Gaia Neri a, Oliver Hutter a, Richard J. Potter b, Jon Major a, Alex Cowan a
a University of Liverpool, UK, University of Liverpool, Liverpool, United Kingdom
b University of Liverpool, UK, University of Liverpool, Liverpool, United Kingdom
nanoGe Fall Meeting
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#SolCat19. (Photo)electrocatalysis for sustainable carbon utilization: mechanisms, methods, and reactor development
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Matthew Mayer and Ludmilla Steier
Poster, D. Alicia Garcia-Osorio, 430
Publication date: 18th July 2019

Carbon dioxide can be converted into useful fuels by using a photoelectrochemical cell. The photocathode is usually a p-type semiconductor, however typically the selectivity and the faradaic efficiencies are low and the hydrogen evolution reaction (HER) is favoured on bare semiconductors. [1] In order to improve the performance, a catalyst can be added on the surface. In particular, molecular catalysts offer several important advantages such as high selectivity and tunability allowing, in principle, a way to avoid the HER. When a molecular catalyst is immobilized on the semiconductor, the semiconductor/catalyst interface offers a junction for rapid spatial and energetic charge separation, where the photogenerated electrons can be rapidly transferred from the semiconductor to the catalyst before the recombination process. [2] Recently, antimony selenide (Sb2Se3) has attracted research interest because Sb and Se are earth-abundant elements, inexpensive and low-toxic; it also has a low band gap (1.2-1.0 eV), and a conduction band minimum at -0.29 V vs. NHE, which makes it a suitable light absorber for photocathodes, however Sb2Se3 electrodes usually show poor stability in aqueous solutions. The stability of Sb2Se3 electrodes has been significantly improved with a layer of TiO2 [3,4] The targeted molecular catalysts for CO2 reduction are Ni(cyc)2+ derivatives, which are non-precious catalysts with high stability and activity for conversion of CO2 to CO. [5,6] In this work, the Ni(cyc)2+ derivatives were immobilized on the surface of FTO/Sb2Se3/TiO2, and CO and H2 were obtained after applying -1.08 V vs Fc+/Fc during 1 h of electrolysis and a light source of 60 mW cm-2. Although the obtained photocurrents were low, the electrode assembly demonstrated to be a promising hybrid photocathode. Additional improvements in cell configuration and immobilization process are required to enhance the performance of the hybrid photocathode.

DAGO acknowledge CONACyT for the PhD scholarship.

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