FABRICATION OF UNIFORM POROUS LAMELLAR ZINC STRUCTURES BY DEALLOYING OF EUTECTIC BINARY ZINC-ALUMINIUM ALLOYS

Abstract

Porous metallic zinc is a promising hostless electrode material for zinc-based energy storage applications due to excellent electrochemical behavior. Among various fabrication methods, dealloying stands out for its simplicity and efficiency. However, challenges such as uneven pore distribution and uncontrollable pore structures compromise the quality of porosity. In this study, highly uniform porous lamellar zinc structures were developed through chemical dealloying of the eutectic binary zinc–aluminium alloy system. The resultant lamellar configuration was finely tuned by adjusting the precursor alloy composition and bimetallic phase distribution. A homogenous zebra-like quasi-periodic lamellar pattern was achieved at eutectic composition of Zn₉₅Al₅ (wt%). This structure exhibited greater uniformity compared to the eutectoid-rich lamellar structure observed in the hypereutectic Zn₉₀Al₁₀ alloy. A large Zn lamellar thickness of 2919.7 ± 371.0 nm and interlamellar spacing of 1248.3 ± 203.6 nm were produced under low solidification rate by furnace cooling. Optimal dealloying parameters of 4 M NaOH at 50 °C were determined, providing ideal balance between the reaction rate and structural stability. The thick lamellae promoted high dealloying rate of 1.988 mg/cm²/h, resulting in high peak-to-valley roughness of 3698 nm. Selective dissolution of the less noble aluminium component left behind the alternating zinc-rich lamellar framework as examined by variable-pressure scanning electron microscopy (VPSEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) spectroscopy. This structure endows abundant pores with consistent interlayer spacing.