Confirmation of Interlayer Sulfidization of Malachite by TOF-SIMS and Principal Component Analysis

In this work, a sulfidization mechanism of malachite was confirmed based on the depth profile product, principal component, and depth profile curve analyses of time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results showed that Cu/S species, including fragment ion peaks of Cu2S+, Cu3S+, S-, HS-, S-2(-), CuS2-, and CuS3-, were present in the inner layers of sulfidized malachite in the positive and negative spectral ranges 75-400 and 30-470 m/z. Na2S reacted with the surface and inner atoms, causing simultaneous sulfidization of malachite on the surface and in the inner layers. The inner layer mainly contained positive fragment ions with large Cu/S ratios. In summary, the interlayer sulfidization phenomenon was confirmed and the differences in sulfidization products between the surface and inner layers were determined.