Graphitic Carbon Nitride Nanosheets Decorated with Cu-Doped Carbon Dots for the Detection and Degradation of Phenolic Pollutants

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The heterogeneous Cu-based solid catalysts have attracted enormous attention of researchers in different potential applications. In this work, a graphitic carbon nitride/copper-doped carbon dots (g-C 3 N 4 /Cu-CDs) nanocomposite with both intrinsic peroxidase- and oxidase-like (POD- and OXD-like) activities was successfully prepared. Due to the synergistic catalytic enhancement and electron transmission provided by g-C 3 N 4, both POD- and OXD-like activities of g-C 3 N 4 /Cu-CDs were significantly improved compared with those of g-C 3 N 4 and Cu-CDs. Moreover, upon the addition of H 2 O 2, g-C 3 N 4 /Cu-CDs could catalyze the oxidation of colorless o -phenylenediamine (OPD) to form a yellow fluorescent product 2,3-diaminophenazine (DAP) with yellow fluorescence. Interestingly, the OPD + H 2 O 2 + g-C 3 N 4 /Cu-CDs system could be inhibited by phenolic compounds, which could efficiently decrease the DAP fluorescence. Based on this, a method for the quantitative detection of total phenolic substances was established. Meanwhile, the use of OXD-like activity of nanocomposites was extended for the degradation of phenols (e.g., 2-CP), which showed a good degradation efficiency. Based on the result that the conversion of Cu + /Cu 2+ /Cu 0 plays pivotal roles in promoting the generation of radicals (i.e., • OH and • O 2 – ), a possible catalytic mechanism of g-C 3 N 4 /Cu-CDs was deduced. These findings showed that the proposed g-C 3 N 4 /Cu-CDs exhibit great potential to become a green catalyst for the degradation of phenolic pollutants in the environment.