Extended Data Fig. 7: Outstanding anti-corrosion performances regardless of the shape and size of Cu materials.

a, SEM images of Cu and Cu-FA (prepared by Method II) wires before and after treatment in 0.1 M NaOH at 60 °C for 60 h and in 3.5 wt% NaCl at 60 °C for 24 h (top), temperature-dependent resistances of Cu and Cu-FA wires (length 10 cm, diameter 1 mm) after heating in air for 24 h (bottom left) and resistance changes of Cu and Cu-FA (prepared by Method II) wires (length 10 cm, diameter 1 mm) after ageing in 0.1 M NaOH at 60 °C for different time periods (bottom right). The data were averaged from three independent measurements. Error bars reflect the standard errors. b, SEM images of the untreated Cu wire and the Cu-FA wire before and after heating at 160 °C in air for 24 h. c, Microphotographs of Cu, Cu-DT, Cu-FA (prepared by Method III) and Cu-FA/DT meshes after a 96-h salt spray test, and their corresponding Raman spectra and relative electric conductivities before (grey) and after (red) the salt spray test. d, Optical photographs of Cu-FA/DT and Cu-FA meshes (prepared by Method III) after immersion in Na₂S solutions of different concentrations for 5 h, and microphotographs of Cu–FA/DT and Cu-FA meshes after 6 h of ageing in 10 mM Na₂S. e, Robust anti-corrosion performance of Cu-FA/DT tubes under wet mechanical conditions; photographs of the outer and inner walls of Cu-FA/DT and bare Cu tubes (inner diameter 1.6 cm) after the wet mechanical test with flowing 3.5% NaCl solutions (flow rate of up to 1,400 l h⁻¹, 10–30 °C) for 96 h and 12 h, respectively, and their corresponding Raman spectra. f, Robust anti-corrosion performance of Cu-FA/DT foils under wet mechanical conditions; photographs of the wet mechanical test set-up, with salty water (3.5% NaCl, 1% Na₂CO₃, 1% Na₂SO₄ and 0.1% NaOH) flowing through the foils, comparison photographs of Cu-FA/DT, bare Cu and patinated Cu foils before and after the wet mechanical tests (72, 12 and 12 h, respectively) and their corresponding Raman spectra after the tests. The polarization parameters of different Cu foils in 0.1 M NaOH solution were measured as follows: E_corr = −222 mV, J_corr = 6.71 μA cm⁻², corrosion rate 78.2 μm yr⁻¹ (bare Cu); E_corr = −212 mV, J_corr = 4.65 μA cm⁻², corrosion rate 54.2 μm yr⁻¹, anti-corrosion enhancement 1.44 (patinated Cu); E_corr = −258 mV, J_corr = 0.067 μA cm⁻², corrosion rate 0.755 μm yr⁻¹, anti-corrosion enhancement 103.6 (Cu-FA/DT). The anti-corrosion enhancement is defined as the ratio of the corrosion rate of the bare Cu foil to that of modified Cu. The patinated Cu foil was prepared by exposing bare Cu foils to 3.5% Na₂CO₃ salt spray for 60 h.