Smartphone-assisted array discrimination of sulfur-containing compounds and colorimetric−fluorescence dual-mode sensor for detection of 1,4-benzenedithiol based on peroxidase-like nanozyme g-C3N4@Cu, N-CDs

Present work reported a novel nanozyme g-C3N4@Cu, N-CDs with excellent peroxidase-like activity obtained by loading Cu and N co-doped carbon dots on g-C3N4 (graphitic carbon nitride). g-C3N4@Cu, N-CDs can catalyze H2O2 to generate hydroxyl radical •OH, which oxidizes o-phenylenediamine to 2,3-diaminophenazine, which emits orange fluorescence under ultraviolet light irradiation. The experimental results confirmed that 1,4-benzenedithiol (BDT) could inhibit the peroxidase-like activity of g-C3N4@Cu, N-CDs. Based the principle above, a colorimetric-fluorescence dual-mode sensor for rapidly sensing of BDT was creatively constructed with assisting of a smartphone. The sensor showed excellent linearity over ranges of 0.75-132 μM and 0.33-60.0 μM with detection limits of 0.32 μM and 0.25 μM for colorimetric and fluorescence detection, respectively. Moreover, a smartphone-assisted colorimetric array sensor was constructed to distinguish six sulfur-containing compounds according to the difference in the degree of inhibition of nanozyme activity by different sulfur-containing compounds. The array sensor could distinguish sulfur-containing compounds at low concentration as low as 0.4 μM. The results validated that the designed sensor was a convenient and fast platform, which could be utilized as a reliably portable tool for the efficient and accurate detection of BDT and the discrimination of multiple sulfur compounds in real water samples.