An extract of fresh guava leaves (Psidium guajava) was used as a green carbon precursor to fabricate blue fluorescent carbon quantum dots (GCQDs) by hydrothermal process. The GCQDs show bright blue fluorescence emission under UV light with an excitation wavelength of 350 nm and emission at 450 nm. The physical structure of GCQDs was characterized by Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), High-resolution transmission electron microscope (HR-TEM) and atomic force microscopy (AFM). GCQDs 80 µg inhibited the growth of waterborne pathogens Escherichia coli and Salmonella typhi. We also investigated the catalytic activity of the GCQDs on the removal of two azo dyes, namely Congo red and bromophenol blue, with and without NaBH₄. The GCQDs showed an excellent reduction of color intensity of both dyes without NaBH₄ within 30 min of treatment.

新鲜番石榴叶（Psidium guajava）的提取物被用作绿色碳前体，通过水热法制造蓝色荧光碳量子点（GCQDs）。GCQD 在激发波长为 350 nm 和发射波长为 450 nm 的紫外光下显示出明亮的蓝色荧光发射。GCQDs的物理结构通过傅里叶变换红外光谱（FT-IR）、拉曼光谱、X射线衍射（XRD）、高分辨率透射电子显微镜（HR-TEM）和原子力显微镜（AFM）表征。GCQDs 80 µg 抑制水性病原体大肠杆菌和伤寒沙门氏菌的生长. 我们还研究了 GCQDs 在去除两种偶氮染料（即刚果红和溴酚蓝）方面的催化活性，有和没有 NaBH ₄。GCQDs在处理 30 分钟内显示出两种染料在不含 NaBH _{4 的}情况下显着降低颜色强度。