Extended Data Fig. 3 | Effect of treatment time and crystallinity on the
anti-corrosion performance of Cu. a, Photographs and microphotographs of
Cu-FA foils after corrosion in 0.1 M NaOH for 24 h as a function of treatment
time. The foils were obtained with the formate treatment at 160 °C for different
periods. b, XRD spectra of different Cu foil samples treated hydrothermally in
the presence of formate in different conditions. Sample 1: Cu-FA foil
(25 μm; Alfa Asear) treated at 160 °C for 0–12 h (Method II). Sample 2: Cu foil
(25 μm; Alfa Asear) treated at 200 °C for 2–24 h (Method I). Sample 3: Cu foil
(10 μm; Aladdin) treated at 200 °C for 0–4 h (Method I). c, Cross-sectional TEM
and high-resolution STEM images of Cu-FA (I–II) and bare Cu foils (III–IV), using
samples prepared by the focused-ion-beam technique. d, Cross-sectional TEM
and high-resolution TEM (HRTEM) images of Cu-FA (1–3) and bare Cu foils (4–6),
using samples prepared by microtoming.