Cellulose nanocrystal-derived hollow mesoporous carbon spheres and their application as a metal-free catalyst

In this contribution, we demonstrate the fabrication of hollow mesoporous carbon spheres (HCSs) derived from cellulose nanocrystals (CNCs). The HCSs were prepared by templating CNCs onto sacrificial silica spheres followed by heat treatment. Mesoporous carbon spheres result from the removal of the silica spheres by etching. The walls of the HCSs are approximately 4 nm thick and are composed of amorphous and graphitic carbon. The catalytic activity of the HCSs was investigated for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH₄). The present investigation reveals the outstanding catalytic activity of these particles. The reaction rate followed pseudo-first order kinetics with k value of 4.72 × 10^-3 s^-1 and activity parameter of 52.2 s^-1 g^-1, which showed superior performance compared to that of metal nanoparticle and metal nanoparticle-carbon hybrid based catalysts.