Enhancement of oxygen permeation flux through the La1.5Sr0.5Ni1-yMnyO4+δ ceramic membranes by manganese doping

•The oxygen permeation of the La1.5Sr0.5Ni1-yMnyO4+δ (y=0-0.3) membranes sharply increases at y=0.3.•The activation energy of oxygen permeation flux decreases by two times in the 0.2≤y≤0.3 range.•These effects are attributed to the enhanced surface exchange rate in La1.5Sr0.5Ni0.7Mn0.3O4+δ.•The concentration of Mn4+ increases with manganese doping level y in La1.5Sr0.5Ni1-yMnyO4+δ (y=0.2, 0.3).•Mixed oxidation state Mn+3/Mn+4 is the key factor defining the rate of surface oxygen exchange in La1.5Sr0.5Ni1-yMnyO4+δ.