Solid-State Synthesis of Metal Nanoparticles Supported on Cellulose Nanocrystals and Their Catalytic Activity

Heterogeneous catalysis has played a critical role in environmental remediation, for example, in processes that generate toxic streams. Thus, there is an ever-increasing need for green, costeffective routes to synthesize highly active catalysts. In this study, a cellulose nanomaterial (cellulose nanocrystals, CNC) was employed as solid support for the nucleation of silver and gold nanoparticles via solid-state synthesis. The process involved solvent-free reduction in ambient conditions of metal precursors on the surface of CNC and in the presence of ascorbic acid. Surface plasmon resonance and X-ray diffraction indicated the successful formation of the metal nano particles, in the form of organic inorganic hybrids. A strong hydrogen bonding was observed between CNC and the metal nanoparticles owing to the high density of hydroxyl groups in CNC, as determined by Fourier transform infrared spectroscopy. Electron microscopies indicated that the silver and gold precursors formed nanoparticles of hexagonal and spherical shape, respectively. The organic inorganic hybrids were demonstrated as the potential catalyst for the reduction of 4-nitrophenol to 4-aminophenol. Overall, we introduce a green, solvent-free, and facile method for the production of noble metal nanoparticles supported on CNC, which offer promise in the scalable synthesis and for application in heterogeneous catalysis.