Enrichment of MnO 2 Nanoparticles with Different N-Doped Carbon Dots as a Robust H 2 O 2 Sensor: a Comparative Study

This study is focused on synthesizing environmentally friendly nano-probes for rapid and sensitive detection of H 2 O 2 . Biogenic manganese oxide nanoparticles were prepared and capped with two different types of nitrogen doped carbon dots. Nanocomposites are designated as NC1 (semicarbazide hydrochloride as a dopant source) and NC2 (urea as a dopant source). Synthesized nanocomposites (NC1 and NC2) were characterized by different techniques. UV-visible spectra depicted peaks at 298 nm (NC1) and 299 nm (NC2). FTIR confirmed the presence of different functional groups at the surface of nanocomposites. XRD showed the amorphous carbon structure of nanocomposites with particle size of 7 nm (NC1) and 6 nm (NC2). Raman spectra showed the graphitic carbon structure. In both cases, D and G bands were observed with I D / I G ratio equal to 0.76 for NC1 and 0.16 for NC2. NC1 depicted linearity for the concentration range of 10–40 µM with LOD and LOQ of 7 and 24 µM, respectively, while NC2 exhibited linearity over the concentration range of 50–80 µM with LOD of 12 µM and LOQ of 40 µM. Percentage recoveries for spiked samples were calculated to be 99.8–101.8 and 98.5–99.1% for NC1 and NC2, respectively.