Plasma synthesis of rhenium nanoparticles as an efficient alternative to platinum nanoparticles for nitroaromatic compound hydrogenations

Rhenium nanoparticles are an attractive alternative to noble metal-based approaches, which show a limited applicability. The catalytic potential and environmental impact of rhenium nanoparticles (ReNPs) were assessed in conjunction with those of platinum nanoparticles (PtNPs). Both of these nanomaterials were synthesized via low-cost pulse-modulated radiofrequency atmospheric pressure glow discharge (pm-rf-APGD). In this context, pm-rf-APGD was used for the first time to synthesize Re-based nanomaterials. The obtained nanoparticles were used as nanocatalysts for hydrogenation of nitroaromatic compounds. Subsequent characterization revealed high efficacy of rhenium nanoparticles in catalysing the reduction of nitroaromatic compounds, which reached up to 100% conversion yields at a rate constant k₁ of 5.5 × 10^{- 2} min^{- 1}. Although the k₁ values obtained for rhenium nanoparticles were lower than those recorded for platinum nanoparticles, this research highlights the economic aspects and explores the possible optimization of catalytic systems. Some putatively disadvantageous environmental impact of rhenium nanoparticles and platinum nanoparticles was demonstrated by the exposure of Raphanus sativus var. oleiferus L. seeds to either rhenium nanoparticles or platinum nanoparticles that resulted in development of the shorter sprouts. Despite this negative environmental impact, the outcomes of this study highlight the potential of rhenium nanoparticles for chemical transformation and emphasize the importance of further insights into the economic and environmental aspects of their application and mitigation strategies.