Tuning of CeO2-MnO2 nano composite in Al-Zn alloy matrix for effective activation

•Nano CeO2-MnO2 composite is tuned for effective activation of Al + 5 wt% Zn alloy.•The composite acts as lattice expander in Al alloy and increases dissolution of Zn.•The composite and Zn in the alloy matrix synergistically activate the Al alloy anode.•A Galvanic efficiency of 92% is achieved with incorporation of 1% composite.•The composite incorporation favours uniform corrosion suppressing pitting corrosion. Efficient Al + 5 wt% Zn sacrificial anode was prepared and its activity was further enhanced by tuning CeO2-MnO2 nano composite in the alloy matrix. The nano composite was prepared by thermal decomposition method and was characterised by XRD and HRTEM. Al + 5 wt% Zn were fabricated by the incorporation of the composite in the alloy matrix. The composite acted as lattice expander in the Al-Zn alloy and increased dissolution of Zn. Very high galvanic efficiency of 92% was achieved by tuning the amount of the composite in the Al-Zn alloy anode. Its uniform corrosion behaviour was evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic polarisation and post consumption microscopic evaluation. A significant lowering in impedance value was achieved by increasing the amount of nano composite in the alloy due to the increased penetration of the oxide film by chloride ions. The composite and Zn in the alloy synergistically activated the Al alloy which facilitated uniform corrosion suppressing pitting corrosion.