Protein particles decorated with Pd nanoparticles for the catalytic reduction of p-nitrophenol to p-aminophenol

Nano-biomaterial hybridization is a promising strategy to generate unique and advanced material properties that are not available with nano- or biomaterials alone. In particular, the surface stabilizer (surfactant)-free synthesis of catalytic metal nanoparticles (NPs) on biological scaffolds such as protein particles (PPs) holds great potential in improving their catalytic performance because the surfactants form an organic layer on the NP surface and severely deactivate the catalytic surface. Here, we report the surfactant-free synthesis of palladium nanoparticles (PdNPs) using PPs as a synthetic scaffold and the significantly improved catalytic performance of the Pd-protein nanocomposites (PdNP-PPs). The PdNP-PPs have many small PdNPs with clean surface and enlarged surface area on the PP surface. Because of the charge property of PPs, the PdNP-PPs are well dispersed without being aggregated in reaction solutions and exhibit much higher catalytic activity and better durability/ recyclability compared with surfactant-coated PdNPs in the reduction reaction converting p-nitrophenol to p-aminophenol.