<p>Phosphorene belongs to the new family of two-dimensional materials consisting of a single or a few layers of atoms. Phosphorene’s excellent properties, such as its intrinsic bandgap energy modulation and high charge carrier mobility, make it a well-suited material for many devices in electronic and optoelectronic. However, phosphorene’s high reactivity and instability in the presence of water and oxygen are major obstacles limiting its use for industrial applications and pose major challenges to its preparation. In this work, we have developed an efficient and inexpensive one-step hydrothermal synthesis method for the synthesis of stable phosphorene aggregates. The size selection process based on the centrifugation technique enabled the selection of powders homogeneous in size and shape. Various techniques were used to characterize the phosphorene aggregate powders prepared, such as XRD, XPS, FEGSEM, Raman, and UV–visible. We complemented this experimental work with a quantitative and qualitative theoretical study, based on DFT and TDDFT, aimed at gaining an in-depth understanding of the formation of oxygen and fluorine bonding to monolayer phosphorene surface, and its role in phosphorene stability. Furthermore, in order to assess the stability and aging of phosphorene aggregates through their optical properties, the effects of oxygen and fluorine adsorbates on the surface of phosphorene aggregates on their optical properties were discussed, considering the influence of their aggregation and size evolution. The results obtained enabled us to understand the stability and aging of phosphorene aggregates prepared by the hydrothermal method.</p>