Zinc cobalt bimetallic nanoparticles embedded in porous nitrogen-doped carbon frameworks for the reduction of nitro comp
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The development of highly efficient and stable inexpensive catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 in an aqueous solution by utilizing metal-organic frameworks (MOFs) as precursor and template remains a hot topic. Herein, a simple self-template strategy was developed to synthesize a porous nitrogen-doped carbon frameworks embedded with zinc and cobalt nanoparticles (Zn0.3Co2.7@NC) catalyst by thermal annealing of the bimetallic zinc-cobalt zeolitic imidazolate framework (Zn0.3Co2.7-ZIF) as an effective precursor and template. The resulting Zn0.3Co2.7@NC catalysts show an excellent catalytic activity for the reduction of 4-NP and the reduction reaction was completed only in 5 min with nearly 100% conversion. The apparent rate constant for the reaction of 4-NP reduction was estimated to be 0.683 min1. Moreover, the catalyst was extended to reduce other nitro compounds and exhibited excellent catalytic activity. When compared to other related catalysts in the literature, the catalytic activity of catalyst is superior. Therefore, the resulting Zn0.3Co2.7@NC is expected to get more extensive application in the field of catalysis.
I. INTRODUCTION
Transition metal nanoparticles (TM NPs) as catalysts have been widely applied in catalysis and other fields in the past few decades because of their excellent physicochemical properties.1–3 However, bare TM NPs tend to coalescence and aggregation in the process of usage because of their high surface energy and high activity, which is a huge limitation in practical application.4–6 So finding a functionalized support or precursor on which TM NPs lie while retaining its physical and chemical characteristics has become a critical challenge. Metal-organic frameworks (MOFs) have attracted increasing attention in diversified fields due to their designable frameworks and tuneable pore structures.7,8 In recent years, MOFs have always been used as ideal precursors for directly producing porous carbon materials by thermal cracking in controllable atmosphere,9–11 which is quite effective for heterogeneous catalysis.12–14 Nitrogen-doped carbon materials obtained by choosing containing nitrogen MOFs (ZIFs) as precursors and functionalized support often exhibit excellent performance for various applications.15–17 Moreover, the perfect compatibility of organic skeleton with a variety of metal ions makes it possible to synthesis of homogeneous multimetallic MOFs.18–21 Contributing Editor: Edson Roberto Leite Address all correspondence to these authors. a) e-mail: [email protected] b) [email protected] DOI: 10.1557/jmr.2017.148
Among most TM NPs, Co NPs have shown the outstanding catalytic activity due to their high activity and magnetic response.5,22,23 Moreover, the incorporation of multiple metals into a single system comparing to a single metal has more advantageous for most applications since the synergistic effect.24 Recently, lots of attention have been paid on developing cobalt-based bimetallic catalysts for various applications. For example, Li et
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