Facile and Green Synthesis of Bismuth Nanoparticles for the Catalytic Reduction of 4-Nitrophenol

The green pathway is considered an alternative to the conventional chemical method for synthesising metal nanoparticles. This study demonstrates a facile biogenic synthesis of bismuth nanoparticles (BiNPs) using Piper chaba stem extract as a reducing and capping source. Synthesised BiNPs were characterised using various analytical tools. XRD analysis confirmed the formation of crystalline BiNPs. FTIR analysis identified the functional groups from P. chaba extract involved in the BiNPs stabilisation process, while zeta potential measurement confirmed their stabilisation. The TEM image revealed spherical nanoparticles with an average size of 15 nm. EDX analysis showed bismuth as the dominant element, with traces of carbon and oxygen from organic moieties on the surface of BiNPs. TGA also supports the existence of phytochemicals with BiNPs and good thermal stability up to 800 degrees C, supporting its suitability for high-temperature applications. The catalytic activity of BiNPs in reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4 showed rapid conversion of 4-NP to 4-AP within 22 min, with a rate constant of 6.77 s(-1) g(-1), demonstrating the excellent catalytic efficiency of BiNPs. Following green chemistry principles, these findings suggest that P. chaba-mediated BiNPs can serve as highly effective nanocatalysts for various chemical transformations and environmental purification processes.