In situ reduction of well-dispersed nickel nanoparticles on hierarchical nickel silicate hollow nanofibers as a highly efficient transition metal catalyst

Abstract

Despite being a promising substitute for noble metals used in nanocatalysts, the inexpensive and earth-abundant transition-metal catalysts are still impractical, mainly due to their low catalytic activity and durability. Therefore, acquiring a highly active and stable transition metal catalyst is urgently desirable. In this paper, we describe a mild method for the synthesis of small-sized nickel nanoparticles (NiNPs) immobilized on hierarchical double-shell nickel silicate hollow nanofibers (NSHNFs) in a large scale. The NiNPs/NSHNFs catalysts show high catalytic activities and excellent stabilities towards the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The reduction has a pseudo-first-order rate constant of 13.21 × 10⁻³ s⁻¹ and an activity parameter of 13.21 × 10⁻³ s⁻¹ mg⁻¹, which are higher than those of the previously reported Ni-based catalysts. In particular, the NiNPs/NSHNFs catalysts can be easily separated from the solution by gravitational sedimentation owing to their unique structure. Therefore, our NiNPs/NSHNFs nanocomposites hold promise for further industrial applications as cheap and effective catalysts.