Figure 1.

Characterization of as‐prepared PBNPs. A) SEM image of PBNPs showed the formation of uniform PBNPs with good monodispersity. B,C) TEM images of cube PBNPs with the average size of ≈80 nm. D) EDS of PBNPs confirmed PBNPs contained potassium (K), iron (Fe), carbon (C), and nitrogen (N) elements. E) Element mappings of K, Fe, C, and N elements in PBNPs. F) XRD pattern of the as‐prepared PBNPs and standard JCPDS Card No. 73‐0687. G) The average hydrodynamic particle diameter of PBNPs indicating good dispersion of these particles in aqueous media. H) UV–vis–NIR absorbance curve of PBNPs displayed a wide absorbance peak around 700 nm. I) FT‐IR spectrum of PBNPs showed an obvious characteristic peak at 2094 cm⁻¹.