Improved electrochemical detection of copper ions in nitrogen doped ta-C films for marine corrosive monitoring

Abstract

The corrosion of copper-based alloy in the harsh marine environment threatens the reliable operation and service life of marine engineering equipment. In this work, the nitrogen modified tetrahedral amorphous carbon (ta-C:N) film electrodes were prepared for marine-oriented copper ions detection. The relationship between structural evolution and electrochemical performance of ta-C:N film electrode tailored by N2 flux was evaluated. The sp2 cluster and the content of sp2-bonded carbon in ta-C:N film were promoted with the increase of N2 flux. XPS results indicated that the variation of N2 flux modified the nitrogen-containing groups of the ta-C:N film electrodes. The optimized ta-C:N film electrode deposited at N2 flux of 3 sccm showed a quasi-reversible electrode behaviors. Moreover, the ta-C:N film electrode exhibited a linear range from 8 × 10−3 mM to 5 mΜ, a detection limit of 8 × 10−3 mM, and good repeatability and reproducibility for Cu2+ detection in 3.5 wt% NaCl solution. The improved Cu2+ sensing properties were ascribed to the enhanced sp2 cluster and the introduction of multiple nitrogen-containing functional groups, especially the pyrrolic nitrogen and graphitic nitrogen. DFT computation and wavefunction analysis revealed that the pyrrolic nitrogen possessed the strongest interaction for copper ions among different nitrogen configurations.