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Hybrid FeNiOOH/α‐Fe 2 O 3 /Graphene Photoelectrodes with Advanced Water Oxidation Performance
Author(s) -
Kormányos Attila,
Kecsenovity Egon,
Honarfar Alireza,
Pullerits Tönu,
Janáky Csaba
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202002124
Subject(s) - graphene , materials science , overlayer , photoelectrolysis , raman spectroscopy , charge carrier , absorption (acoustics) , spectroscopy , chemical engineering , nanotechnology , optoelectronics , electrode , optics , electrolysis , composite material , chemistry , physics , engineering , quantum mechanics , electrolyte
In this study, the photoelectrochemical behavior of electrodeposited FeNiOOH/Fe 2 O 3 /graphene nanohybrid electrodes is investigated, which has precisely controlled structure and composition. The photoelectrode assembly is designed in a bioinspired manner where each component has its own function: Fe 2 O 3 is responsible for the absorption of light, the graphene framework for proper charge carrier transport, while the FeNiOOH overlayer for facile water oxidation. The effect of each component on the photoelectrochemical behavior is studied by linear sweep photovoltammetry, incident photon‐to‐charge carrier conversion efficiency measurements, and long‐term photoelectrolysis. 2.6 times higher photocurrents are obtained for the best‐performing FeNiOOH/Fe 2 O 3 /graphene system compared to its pristine Fe 2 O 3 counterpart. Transient absorption spectroscopy measurements reveal an increased hole‐lifetime in the case of the Fe 2 O 3 /graphene samples. Long‐term photoelectrolysis measurements in combination with Raman spectroscopy, however, prove that the underlying nanocarbon framework is corroded by the photogenerated holes. This issue is tackled by the electrodeposition of a thin FeNiOOH overlayer, which rapidly accepts the photogenerated holes from Fe 2 O 3 , thus eliminating the pathway leading to the corrosion of graphene.