Electronic Theses and Dissertation

Nadiatul firda (2026). sintesis dan optimasi n-doped carbon quantum dots berbasis arang tandan kosong kelapa sawit menggunakan metode microwave carbon quantum dots (cqds) merupakan nanomaterial karbon berukuran kurang dari 10 nm yang memiliki sifat fotoluminesensi tinggi dan berpotensi diaplikasikan pada bidang sensor, bioimaging, serta optoelektronik. penelitian ini bertujuan mensintesis, menentukan kondisi optimum, dan mengarakterisasi nitrogen-doped carbon quantum dots (n-cqds) dari arang tandan kosong kelapa sawit (tkks) menggunakan metode microwave dengan penambahan asam l-aspartat sebagai sumber nitrogen. optimasi dilakukan menggunakan rsm dengan rancangan box-behnken design (bbd). karakterisasi meliputi uv-vis, konduktivitas listrik, ftir, pl, hrtem, dan dsc-tga. hasil penelitian menunjukkan kondisi sintesis optimum diperoleh pada massa asam l-aspartat 0,273 g/100 ml, waktu iradiasi 8 menit, dan daya microwave 200 w. n-cqds yang dihasilkan berwarna cokelat muda pada cahaya tampak dan memancarkan fluoresensi biru di bawah sinar uv. karakterisasi uv-vis menunjukkan transisi elektronik π–π* pada ikatan c=c dan transisi n–π* pada gugus c=n/c–n, dengan nilai band gap optik sebesar 5,27 ev. karakterisasi pl menunjukkan emisi biru pada panjang gelombang 431 nm dengan intensitas fluoresensi 760,322 a.u., quantum yield 9%, fwhm 98 nm, dan stokes shift 1,00 ev. analisis ftir mengonfirmasi terbentuknya gugus fungsi o–h, n–h, c–h, c=c/c=n, c–o, dan c–n. hrtem menunjukkan partikel berbentuk hampir sferis dengan diameter rata-rata 5,976 ± 1,962 nm, sedangkan analisis dsc-tga menunjukkan bahwa n-cqds memiliki stabilitas termal yang baik hingga sekitar 250°c dan mengalami tiga tahap dekomposisi termal, yaitu penguapan air teradsorpsi, dekomposisi gugus fungsi permukaan, serta degradasi inti karbon. berdasarkan hasil penelitian, n-cqds berhasil disintesis dari arang tkks menggunakan metode microwave dan memiliki karakteristik optik, struktural, serta termal yang baik. kata kunci: n-cqds, tandan kosong kelapa sawit, microwave, response surface methodology, fotoluminesensi.

Nadiatul Firda (2026). Synthesis and Optimization of Nitrogen-Doped Carbon Quantum Dots Derived from Oil Palm Empty Fruit Bunch Charcoal Using the Microwave Method Carbon Quantum Dots (CQDs) are carbon-based nanomaterials with sizes below 10 nm that exhibit excellent photoluminescent properties and have potential applications in sensing, bioimaging, and optoelectronics. This study aimed to synthesize, determine the optimum synthesis conditions, and characterize nitrogen-doped carbon quantum dots (N-CQDs) derived from oil palm empty fruit bunch (OPEFB) charcoal using a microwave-assisted method with the addition of L-aspartic acid as the nitrogen source. The optimization was carried out using Response Surface Methodology (RSM) based on a Box–Behnken Design (BBD). The synthesized N-CQDs were characterized using UV–Vis spectroscopy, electrical conductivity measurements, Fourier Transform Infrared (FTIR) spectroscopy, PL, High-Resolution Transmission Electron Microscopy (HRTEM), and Differential Scanning Calorimetry–Thermogravimetric Analysis (DSC–TGA). The results showed that the optimum synthesis conditions were obtained at an L-aspartic acid concentration of 0.273 g/100 mL, an irradiation time of 8 min, and a microwave power of 200 W. The resulting N-CQDs appeared light brown under visible light and exhibited blue fluorescence under UV irradiation. UV–Vis analysis revealed π–π* electronic transitions associated with C=C bonds and n–π* transitions associated with C=N/C–N functional groups, with an optical band gap of 5.27 eV. Photoluminescence analysis showed blue emission at 431 nm with a fluorescence intensity of 760,322 a.u., a quantum yield of 9%, a full width at half maximum (FWHM) of 98 nm, and a Stokes shift of 1.00 eV. FTIR analysis confirmed the presence of O–H, N–H, C–H, C=C/C=N, C–O, and C–N functional groups. HRTEM analysis revealed nearly spherical particles with an average diameter of 5,976 ± 1,962 nm, while DSC–TGA analysis indicated that the N-CQDs possessed good thermal stability up to approximately 250 °C and underwent three stages of thermal decomposition, namely the evaporation of adsorbed water, decomposition of surface functional groups, and degradation of the carbon core. Based on the results of this study, N-CQDs were successfully synthesized from OPEFB charcoal using the microwave-assisted method and exhibited favorable optical, structural, and thermal characteristics. Keywords: N-CQDs, oil palm empty fruit bunch, microwave, Response Surface Methodology, photoluminescence.