Boron nanoparticles (BNPs) produced by ns-laser ablation in water: synthesis and characterization

Boron nanoparticles (BNPs) are attractive nanomaterials for their employment in many applications, such as neutron detection, boron neutron capture therapy, proton boron capture therapy and nuclear fusion. Depending on the specific application, 10B or 11B isotopes can be used. Nevertheless, there are significant challenges in developing suitable BNPs using both conventional chemical synthesis routes and dry fabrication techniques. In this study we report BNPs directly synthetised in water by pulsed Laser Ablation in Liquid (PLAL). Nanoparticles of elemental boron have been generated by laser ablation of a sintered 10B target in MilliQ water by employing ns laser pulse. The ablation resulted in BNPs and boron target micro-fragments with hydrogen gas and boric acid as by-products. Simple washing steps were used to obtain clean BNPs in water. The BNPs showed a narrow size distribution between 3 and 4 nm and their stability in water was induced by a thin layer of boron oxide surrounds BNPs. The BNPs were fully characterized by the chemical and structural point of view employing several techniques. A discussion on boron chemical reactions during laser ablation in water and after the NPs were released in solution was done.