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Significant Reduction in NiO Band Gap Upon Formation of Li x Ni 1− x O alloys: Applications To Solar Energy Conversion
Author(s) -
Alidoust Nima,
Toroker Maytal Caspary,
Keith John A.,
Carter Emily A.
Publication year - 2014
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201300595
Subject(s) - non blocking i/o , band gap , photocathode , materials science , semiconductor , optoelectronics , hydrogen , water splitting , photocatalysis , chemistry , physics , electron , biochemistry , organic chemistry , quantum mechanics , catalysis
Long‐term sustainable solar energy conversion relies on identifying economical and versatile semiconductor materials with appropriate band structures for photovoltaic and photocatalytic applications (e.g., band gaps of ∼1.5–2.0 eV). Nickel oxide (NiO) is an inexpensive yet highly promising candidate. Its charge‐transfer character may lead to longer carrier lifetimes needed for higher efficiencies, and its conduction band edge is suitable for driving hydrogen evolution via water‐splitting. However, NiO’s large band gap (∼4 eV) severely limits its use in practical applications. Our first‐principles quantum mechanics calculations show band gaps dramatically decrease to ∼2.0 eV when NiO is alloyed with Li 2 O. We show that Li x Ni 1− x O alloys (with x= 0.125 and 0.25) are p‐type semiconductors, contain states with no impurity levels in the gap and maintain NiO’s desirable charge‐transfer character. Lastly, we show that the alloys have potential for photoelectrochemical applications, with band edges well‐placed for photocatalytic hydrogen production and CO 2 reduction, as well as in tandem dye‐sensitized solar cells as a photocathode.