Nitrogen-rich hierarchical porous carbon supported Ag nanoparticles for efficient nitrophenol reduction

Porous carbons with predefined porosity and customizable pore structures are promising templates for the synthesis of highly dispersed metal nanoparticles. Herein, nitrogen-rich hierarchical porous carbon was synthesized using rationally designed microporous organic polymer as the precursor by high-temperature treatment with potassium hydroxide activation. Due to the meso-microporous structure and high Brunauer-Emmett-Teller (BET) surface area (2585 m² g⁻¹), the resulting porous carbon has been employed as the catalyst support and silver nanoparticles (Ag NPs) were evenly dispersed on the surface or embedded within carbon matrix. Compared with polymer precursor-supported silver nanoparticles, the porous carbon-supported silver nanoparticles show higher catalytic activity in 4-nitrophenol reduction, which can be attributed to the smaller silver particles size (3.9 nm) and the hierarchical porous structure of the support material. The pseudo-first-order rate constant (k) and catalytic activity parameter (turnover frequency, TOF) is estimated to be 8.7 × 10⁻¹ min⁻¹ and 1.90 × 10⁻⁵ mol g⁻¹ s⁻¹, respectively. This is the highest value reported to date for Ag-based catalysts. More importantly, the porous composite catalyst is highly stable, easy to recycle and reused without losing its catalytic activity. The present work opens new opportunities for the design and preparation of metal nanoparticles/porous carbon composite materials.