Significant Reduction in NiO Band Gap Upon Formation of LixNi1−xO alloys: Applications To Solar Energy Conversion

Authors:
Publisher website
Google Scholar
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.

This publication has 69 references indexed in Scilit: