Abstract
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 Li2O. We show that LixNi1-xO 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 CO2 reduction, as well as in tandem dye-sensitized solar cells as a photocathode.
Original language | English (US) |
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Pages (from-to) | 195-201 |
Number of pages | 7 |
Journal | ChemSusChem |
Volume | 7 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2014 |
All Science Journal Classification (ASJC) codes
- General Chemical Engineering
- General Energy
- General Materials Science
- Environmental Chemistry
Keywords
- Band gap engineering
- Dye-sensitized solar cells
- Energy conversion
- Photocatalysis
- Photovoltaics