Sintesis Nitrogen-Doped Carbon Dots Menggunakan Metode Solvotermal dari Kulit Jengkol sebagai Pendeteksi Ion Hg2+

Abstract

Nitrogen Doped-Carbon dots are fluorescent nanoparticles that are easily synthesized from natural raw materials. Jengkol peel is a biomass waste containing phytochemical compounds that can be used as a precursor to synthesize carbon dots and use ethylenediamine (EDA) as a nitrogen dopant with variations of 5, 10, and 15 v/v%. Then the mixture was synthesized by solvothermal method at 200 oC for seven hours. This study aimed to determine the characteristics of carbon dots (CDs) and nitrogen-doped carbon dots (N-CDs) and to analyze the selectivity and sensitivity of Hg2+ ion detectors. Characteristics of CDs and N-CDs were analyzed using a UV lamp, UV-Vis Spectrophotometry, PL, FTIR, HR-TEM, and XPS. This study showed that CDs and N-CDs were successfully synthesized, confirmed by fluorescence with a bluish-green color under a 365 nm UV lamp, and analysis by HR-TEM showed spherical particles measuring 3.92 and 4.49 nm. UV-Vis analysis, CDs had an absorption peak of 286 nm, while N-CDs had an absorption peak of 284 and 397 nm. PL test results show that adding EDA can increase the PL intensity and quantum yield and cause a red shift at the emission wavelength. N-CDs 10% had the best fluorescence properties with a quantum yield of 42% and PL intensity 68 times greater than that of CDs with a quantum yield of 23%. FTIR analysis of all samples showed the presence of O-H, C=C, C=O, C-H, and C-O-C groups. N-CDs have a C=N group which indicates Nitrogen has been successfully doped on the N-CDs surface. XPS analysis of CDs and N-CDs yielded two elemental components, namely C1s and O1s at 284.68 eV and 285.68 eV from C=C and C=O and N-CDs had an essential component of N1s at 546.34 eV. The fluorescence property of 10% N-CDs was used to detect Hg2+ ions based on fluorescence quenching. The results revealed the selectivity and sensitivity of N-CDs to Hg2+ ions with an LoD of 0.22 μM in the Hg2+ ion concentration range of 0 -100 μM.