Electrochemical fabrication and characterisation of nanoporous copper from CuZn alloy precursors at macro and microscale electrode arrays

Nanoporous copper (NPC) materials possess high surface area, enhanced electrochemical performance, and tunable porosity, making them ideal for sensing and catalytic applications. In this study, NPC was fabricated and characterised from CuZn alloy precursors deposited at both macro and micro-scale electrodes. CuZn alloys were electrodeposited using citrate-complexed sulphate baths, with two distinct modifications to the base bath: saccharin was added for macro-scale deposition to improve adhesion, while pH adjustment was used at the micro-scale to optimise alloy composition and etching behaviour. Physical characterisation using SEM, AFM, EDX, XRD, and TEM confirmed the formation of nanoporous architectures with consistent crystallographic features across scales. Electrochemical characterisation demonstrated significant increases in electrochemical and real surface areas, with NPC exhibiting significant surface area enhancements, corresponding to a surface-area-to-volume ratio of 2.3 × 10⁶ cm^-1 at the macro-scale and 4.9 × 10⁵ cm^-1 at the micro-scale, a 289-fold and 47-fold increase over their respective geometric surface areas (GSA). These findings highlight the need for scale-specific bath optimisation to enable reliable NPC formation on microelectrodes, supporting their integration into high-performance electrochemical sensing microdisc array (MDA) platforms.