Dual-functional Cu_xO/Cu electrodes for supercapacitors and non-enzymatic glucose sensors fabricated by femtosecond laser enhanced thermal oxidation

A facile approach is proposed to fabricate porous Cu_xO nanostructures on copper foil. By conducting femtosecond laser ablation and thermal oxidation, in-situ Cu_xO nanostructures growth was induced on the copper foil. These structures act as active and sensitive materials for supercapacitor and glucose sensor electrodes. By controlling the laser fluences and scan rates, various morphologies were obtained. The specific capacitance of the porous Cu_xO/Cu electrode reached 156.72 mF cm⁻² at the current density of 1 mA cm⁻², which was larger than that obtained without femtosecond laser ablation, and it was maintained at 83% as the current density increased to 12 mA cm⁻². Through femtosecond laser pretreatment, micro/nanostructures were patterned on copper foil surface, enhancing the surface specific area for redox reaction. In addition, the sidewalls of the patterned structures offered nucleation sites of the diffused Cu ion and promoted the growth of copper oxide nanowires. Moreover, the non-enzymatic glucose sensors of the porous Cu_xO/Cu electrode had two linear ranges of 0.01–0.2 mM and 0.5–1.6 mM with the sensitivities of 1212.016 and 852.798 μA mM⁻¹, respectively. These results indicate that the porous Cu_xO nanostructures and nanowires prepared using this facile method have potential applications in supercapacitor and enzyme-less glucose sensor electrodes.