Figure 6.
The dynamic response (the green line) toward reducing gas (i.e., ethanol vapors) under visible light irradiation that corresponded to: (a) photo-activation before target gas exposure has been introduced, (b) target gas interacts with photo-induced oxygen ion and attaches on the surface (photo-adsorption process), (c) photo-desorption process when target gas is detached from the surface, (d) energy band diagram photo-activation before interaction with target gas, (e) photo-adsorption process causes a decreasing the width of HAL and increasing of the electrical resistance, and (f) photo-desorption process causes an increasing the width of HAL and resulting in a decrease the electrical resistance of CaFe2O4.