Preparation of PdNPs doped chitosan-based composite hydrogels as highly efficient catalysts for reduction of 4-nitrophenol

The development of functional hydrogel materials for applications in catalysis has attracted great research interest, especially in aqueous phase catalysis. However, preparation of new structural hydrogel catalysts with enhanced catalytic activity still remains a challenge. In this study, a series of Pd nanoparticles (PdNPs) doped chitosan (CS)-based composite hydrogels were successfully prepared by adding graphene oxide (GO), carbon nanotubes (CNTs) and layered double hydrotalcites (LDHs) to CS hydrogel with glutaraldehyde as a cross-linking agent and in situ growing PdNPs. The structure and morphology analysis indicated that chitosan-based composite hydrogels could be used as carriers to load PdNPs and effectively prevent the agglomeration of PdNPs. Subsequently, 4-nitrophenol (4-NP) catalytic reaction was used as a typical model to evaluate catalytic performances of chitosan (CS)-based composite hydrogel catalysts. The obtained chitosan-based composite hydrogel catalysts exhibited better catalytic activity than that of PdNPs doped CS hydrogel catalyst (CS-PdNPs) and reusability for the reduction of 4-nitrophenol in water. The catalytic process conformed to the pseudo-first-order kinetic equation. Moreover, chitosan-based composite hydrogel catalysts containing CNTs had the best catalytic performance since the particle size of PdNPs was the smallest among three kinds of chitosan-based composite hydrogel catalysts. This work provides new ideas for the preparation of stable and efficient precious metal nanoparticle catalysts for applications in aqueous phase catalysis.

Automated summary

A series of Pd nanoparticle (PdNPs) doped chitosan (CS)-based composite hydrogel catalysts were successfully prepared in this study, showing improved catalytic activity and reusability compared to traditional CS-PdNPs catalysts. Composite hydrogel catalysts containing carbon nanotubes demonstrated the best catalytic performance with the smallest particle size of PdNPs. This work provides new insights for the development of stable and efficient precious metal nanoparticle catalysts for aqueous phase catalysis.