PHB-CS nanosphere-supported heterobimetallic catalysts with Au and Pd for dye degradation and nitrophenol reduction in water

Poly(3-hydroxybutyrate) (PHB) has emerged as a promising biodegradable polymer with extensive potential for diverse applications. When modified with chitosan (CS), PHB demonstrates enhanced metal-loading capabilities, significantly expanding its utility in environmental fields. In this study, a green heterobimetallic gold (Au) and palladium (Pd) catalyst (designated as Au/Pd@PHB-CS), was synthesized through a sequential coordination reduction process on the surface of the PHB-CS nanosphere. The resulting bimetallic nanoparticles on the nanosphere predominantly exhibit a particle size of approximately 4.0 ± 0.9   nm and expose a substantial number of highly active crystal planes. Catalysts possess adsorption capacities for three pollutants: congo red (CR), methylene blue (MB) and 4-nitrophenol (4-NP). Besides, catalysts with low bimetallic loading of Au (0.11   wt%) and Pd (0.11   wt%) show significant removal efficiencies for the three pollutants. Notably, in the degradation of CR, the catalyst exhibits complete reduction of CR with exceptionally fast reaction kinetics. Furthermore, the catalyst maintains a high catalytic activity (95%) after multiple cycles of utilization. Compared to monometallic Au or Pd catalysts, bimetallic catalysts exhibit significantly enhanced reaction activity due to the synergistic interaction between the two metal components. This improved catalytic performance underscores the potential of PHB-based materials as effective catalyst supports, broadening their research and application prospects in catalysis.