Sculpturing metal foams toward bifunctional 3D copper oxide nanowire arrays for pseudo-capacitance and enzyme-free hydrogen peroxide detection

Abstract

Commercial copper foams have been tailored by a highly scalable method combining room-temperature wet-chemical etching and hydroxide thermolysis into a three-dimensional copper oxide nanowire array–copper (3D-CuONA–Cu) composite with macroporous voids and large-area fur-like nanowire array structures, whose structures and compositions were studied employing electron microscopy, X-ray diffraction (XRD) and Raman spectroscopy. The 3D-CuONA–Cu composite monolith was used as a free-standing electrode for pseudo-capacitive energy storage and enzyme-free H₂O₂ detection. Thanks to the 3D electrode architecture and the high-density in situ formed electroactive nanoarrays, an enhanced capacitance of 608 mF cm⁻² at 2 mV s⁻¹ was achieved, with an 88.6% capacity retention after 4000 cycles observed at the high current density of 30 mA cm⁻². For enzyme-free H₂O₂ sensing, an extraordinary sensitivity of 5.75 mA mM⁻¹ cm⁻² and a low detection limit of 0.56 μM were achieved. This prototype sensor also exhibited eligible selectivity and feasibility for real sample analysis.