A Comparative Study of Copper-doped and Copper, Nitrogen Co-doped DLC Film Electrode and Its Electrochemical Properties

Abstract

Copper (Cu), Nitrogen (N) Co-doped diamond-like carbon ((Cu:N)-DLC) films and Cu doped DLC (Cu-DLC) films were fabricated by high power impulse magnetron sputtering technique (HiPIMS). The influence of copper and nitrogen incorporation on the microstructure and electrochemical properties of Cu-DLC and (Cu:N)-DLC films were investigated by X-ray photoelectron spectroscopy, raman spectra and electrochemical workstation. The surface of all the films is cauliflower-like clusters, no obvious large particle Cu clusters can be observed. XRD patterns of theses films have only diffraction peak of copper and no other compounds. Raman spectra illustrate that Id/Ig varies from 2.79 to 3.01 as the N contents changes. XPS results identify that Cu does not form compounds or solid solution into DLC films. Electrochemical tests show that the electrode activity gradually increases with increasing the N contents of (Cu:N)-DLC electrode. Compared with (Cu:N)-DLC electrode, Cu-DLC electrode has a faster electron transfer rate (K0 is 1.88 × 10−2 cms−1), low transfer resistance (227.0 Ωcm2), and a higher electrochemical activity (ΔEp is 93 mV). Consequently, the electrochemical properties of Cu doped DLC films are better than that of Cu, N co-doped DLC films.