Fabrication of platinum nanoparticles decorated on nitrogen enriched carbon spheres for nitroaromatics reduction under batch and continuous flow conditions

The chemical reduction of toxic nitroarenes (NAs) into high industrially valuable aminoarenes by utilizing novel catalysts is an essential and desirable for sustainable development. In this work, the synthesis of ultra-small platinum nanoparticles modified nitrogen enriched carbon spheres (Pt@NCS) as a catalyst for catalytic reduction of NAs in the mild reaction conditions. The structural and morphological characteristics of Pt@NCS were characterized by XRD, Raman, SEM, HR-TEM and FT-IR techniques. The HR-TEM images confirmed that the PtNPs anchored onto the surface of NCS support with an average particle size of 2.10 +/- 0.57 nm. The Pt@NCS catalyst displayed excellent catalytic activity for the catalytic reduction of various NAs such as 4-nitrophenol (4-NP) (18 min, 0.2260 min(-1)), 4-nitroaniline (4-NA) (16 min, 0.3078 min(-1)), 2-nitrophenol (2-NP) (14 min, 0.2514 min(-1)), 4-(4-nitrophenyl)morpholine (4-NM) (14 min, 0.3758 min(-1)) and 4-(2-fluoro-4-nitrophenyl)morpholine (4-FNM) (11 min, 0.4470 min(-1)) under mild reaction conditions. The Pt@NCS catalyst exhibited exceptional recyclability, effectively reducing >98 % of 4-NP within 18 min even after undergoing seven successive cycles in static experiments. The Pt@NCS catalyst displayed a higher catalytic performance for the reduction of 4-NP, when compared with the earlier reported Pt based catalysts. In addition, the continuous-flow catalytic test demonstrated a conversion efficiency of over 99 % and maintained stability over 10 cycles, suggesting promising potential for industrial applications. This study provides facile strategy to produce Pt@NCS catalyst, a high-performance catalyst for continuous flow catalytic reduction of various toxic contaminants in wastewater.