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Back‐Illuminated Si‐Based Photoanode with Nickel Cobalt Oxide Catalytic Protection Layer
Author(s) -
Bae Dowon,
Mei Bastian,
Frydendal Rasmus,
Pedersen Thomas,
Seger Brian,
Hansen Ole,
Vesborg Peter C. K.,
Chorkendorff Ib
Publication year - 2016
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201500554
Subject(s) - photocurrent , materials science , catalysis , tandem , nickel , stack (abstract data type) , water splitting , oxide , degradation (telecommunications) , layer (electronics) , band gap , cobalt , optoelectronics , chemical engineering , photocatalysis , nanotechnology , chemistry , metallurgy , composite material , electrical engineering , biochemistry , computer science , programming language , engineering
Si is an excellent photo‐absorber for use in dual‐band‐gap photoelectrochemical water splitting. We investigate photoanodes with n + pp + ‐Si configuration under back‐side illumination, which is suited to work in a tandem device stack. A co‐sputtered NiCoO x film coupled to the Si was used as a protective catalyst for the water oxidation reaction in 1 m KOH. The sample showed a high photocurrent (21 mA cm −2 ) under red‐light illumination (38.6 mW cm −2 ). Long‐term stability testing showed a gradual decrease of activity in the beginning, and then the activity increased, yielding a cathodic shift of the onset voltage (>50 mV), likely owing to the divergent response of Ni and Co to the Fe present in KOH. Once the activity of the sample stabilized, no further degradation was observed for the following 6 days, indicating that the demonstrated back‐illuminated photoanode configuration can be considered a promising architecture for use as a bottom cell of the tandem water‐splitting device under alkaline conditions.