Buky Wahyu Pratama, Rini Widyaningrum, Andreas Setiawan, Wipsar Sunu Brams Dwandaru, Mitrayana
Soursop leaves, rich in functional groups such as hydroxyl (–OH) and carbonyl (–C=O), were used for the green synthesis of carbon dots (CDs), nanoscale carbon-based particles, through a controlled heating process at temperatures ranging from 50 to 150 °C. The resulting CDs exhibited remarkable nanoscale properties, with uniform, tunable optical and electronic properties, which were confirmed by ultraviolet–visible (UV–Vis) spectroscopy, Fourier–transform infrared (FTIR) spectroscopy, fluorescence analysis, and particle size measurements. UV–Vis spectroscopy revealed a strong absorption peak in the UV region at around 300 nm, which increased with increasing temperature owing to enhanced carbonization, accompanied by a corresponding widening of the band gap at the nanoscale. FTIR analysis revealed a temperature-dependent transition from –OH–dominated surfaces at lower temperatures to carbonyl-enriched surfaces at higher temperatures. Fluorescence analysis exhibited a red shift in emission wavelength with increasing temperature, which correlated with a reduction in the nanometer-sized particle size, as confirmed by particle size analysis. Characterization via high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray (EDX) spectroscopy confirmed the spherical shape, uniform size nanoscale distribution, and high carbon content of CDs. These findings reveal the potential of nanoscale soursop leaf–derived CDs for applications in UV-based sensing and bioimaging owing to their nano sensors due to their tunable band gap, optical properties, and stability. © 2026 The Author(s). To view a copy of this.
Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta, Indonesia; Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Universitas Gadjah Mada, Yogyakarta, Indonesia; Department of Physics, Faculty of Science and Mathematics, Universitas Kristen Satya Wacana, Salatiga, Indonesia; Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Yogyakarta, Yogyakarta, Indonesia; Geological Engineering Department, Faculty of Engineering, Universitas Jenderal Soedirman, Purbalingga, Indonesia
