N-doped carbon quantum dots as corrosion inhibitor for ultra-high voltage etched Al foil

In this work, the N-doped carbon quantum dots (N-CQDs) were synthesized by hydrothermal method, and introduced into the preparation process of ultra-high voltage etched Al foil as corrosion inhibitor, in order to alleviate its over-etching (tunnels clustering and overall thinning), thus to increase its specific capacitance. N-CQDs were characterized by ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometer (EDS). The effects of N-CQDs on etched tunnels, cross section of tunnel tunnels and electrochemical behavior of etched Al foil were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), open circuit potential (OCP), cyclic voltammetry curve (CV), potentiodynamic polarization curves (PDP) and electrochemical impedance spectroscopy (EIS). As a result, when 100 mg·L−1 N-CQDs is added, the over-etching on etched Al foil surface is obviously modified, together with the extended depth, the relieved tunnels clustering, and the lowed Al foil weight loss ratio. Meanwhile, compared with the sample without N-CQDs, the specific capacitance of the ultra-high voltage formed foils prepared by anodizing at 600 V increased by 30 % from 0.49 μF·cm−2 to 0.64 μF·cm−2.