Iron Oxychalcogenides and Their Photocurrent Responses

Abstract

We report here the results of an experimental investigation of the electronic properties and photocurrent responses of the CaFeO Q and La ₂O ₂Fe ₂O Q ₂ phases and a computational study of the electronic structure of polar CaFeOSe. We find that both CaFeO Q ( Q = S and Se) have band gaps and conduction band edge positions compatible with light-driven photocatalytic water splitting, although the oxysulfide suffers from degradation due to the oxidation of Fe ²⁺ sites. The higher O/ Q ratio in the Fe ²⁺ coordination environment in CaFeOSe increases its stability without increasing the band gap beyond the visible range. The photocurrent CaFeOSe shows fast electron–hole separation, consistent with calculated carrier effective masses. These results suggest that these iron oxychalcogenides warrant further study to optimize their stability and morphology for photocatalytic and other photoactive applications.

Abstract

Iron oxychalcogenides are investigated for photoactivity. Our experimental work (including photocurrent and photocatalysis measurements) is complemented by DFT studies to demonstrate the potential of iron oxychalcogenides for photoactive behavior. In particular, the polar oxyselenide CaFeSeO is experimentally shown to have fast electron−hole separation and migration, consistent with the low values calculated for electron and hole effective masses.