Strategy for Synthesizing Porous Cellulose Nanocrystal Supported Metal Nanocatalysts

This paper describes a novel platform to prepare small and uniformly distributed metal nanoparticles (MNPs) on cellulose nanocrystals for use as high performance sustainable nanocatalysts. The model platinum or palladium NPs (1-2 nm in size) were immobilized and chemically reduced onto melamine-formaldehyde (MF) coated cellulose nanocrystals (MFCNCs). The MF coating was critical for the uniform generation and size-control of MNPs. The contribution of MF resin to optimal MNP synthesis includes: (1) increased surface area with its spongelike structure, (2) enhanced affinity to metals through chelation with nitrogen functionalities, and (3) effective MNP size control due to the mesoporous structure. The MNP/MFCNC system significantly improved catalytic activity as demonstrated by the reduction of 4-nitrophenol with Pd/MFCNCs with a turnover frequency of 3168 h(-1). Our synthesis does not require any complicated apparatus or harsh reaction conditions. The proposed strategy is well-suited for the synthesis of a wide range of metal nanocatalysts characterized by a particle size of 1 to 2 nm and superior catalytic activity.