Efficient electrosynthesis of highly active Cu 3 (BTC) 2 -MOF and its catalytic application to chemical reduction R. Senthil Kumar a , S. Senthil Kumar b , M. Anbu Kulandainathan a,⇑ a Electro Organic Division, Central Electrochemical Research Institute, Karaikudi, India b Department of Chemistry and Biochemistry, The University of Texas at Austin, USA article info Article history: Received 16 July 2012 Received in revised form 28 August 2012 Accepted 27 September 2012 Available online 6 October 2012 Keywords: Electrochemical synthesis Metal organic framework Cu 3 (BTC) 2 Chemical reduction p-Nitrophenol abstract Cu 3 (BTC) 2 (Metal organic frameworks-MOF) synthesized through electrochemical route and is used as an catalyst for chemical reduction of nitrophenol in the presence of excess NaBH 4 . Optimization studies for the electrochemical parameters have been demonstrated in order to get 97.51% yield with respect to cop- per dissolution. Synthesized Cu 3 (BTC) 2 is characterized by XRD, FT-IR, SEM, TEM, EDX, BET, TGA and XPS and the results reveal that supporting electrolyte, current density play a crucial role in controlling the particle size and also improving the yield of MOF. The SEM and TEM studies show that the morphology of the synthesized particles is cubic in nature and the particle size is 10–20 nm. The oxidation state of Cu in the synthesized Cu 3 (BTC) 2 found to be +2 from XPS studies. Synthesized Cu 3 (BTC) 2 -MOF function as an effective catalyst to activate the reduction of p-nitrophenol to p-aminophenol in the presence of excess NaBH 4 and the calculated apparent rate constant of 8.69  10 2 s 1 is found to be higher than the other supported noble metal nanoparticle and polymer nanocomposites. Ó 2012 Elsevier Inc. All rights reserved. 1. Introduction In the past few decades, many researchers gave much attention to develop newer synthetic protocols for preparing highly crystal- line porous Metal organic frameworks (MOF), which consists of both inorganic and organic moieties exclusively linked by strong bonds. Based on the metal ions, metal clusters and organic ligands more diversity in the synthesis was possible. Since extra-large pore solids with relatively high thermal stability have been synthesized and these exhibit novel fascinating three-dimensional (3D) topolo- gies. MOFs can exhibit tunable chemical functionality, exception- ally high surface areas (500–6500 m 2 g 1 ) with large pore sizes (3–35 A°) [1] and tailorable nanoporous host materials as robust solids with high thermal and mechanical stability. These materials are having rigid pores, which are not collapsed upon addition or re- moval of solvent or other guest molecules occupying the pores. Several framework materials are derived from benzene-1,3,5-tri- carboxylic acid (BTC), in combination with different metal ions and clusters. Among them, HKUST-1 (Cu 3 (BTC) 2 ) is the most important material [2], which exhibits highly porous nature and has promised material for a number of diverse potential applica- tions including gas storage, gas separation and catalysis in organic synthesis [3–15]. The conventional routes for the synthesis of MOF have some limitation on scaling up. Moreover, some authors attempted faster and more efficient synthetic routes like microwave synthesis [16] and sonochemical synthesis [17] of MOFs. But, there are only a few reports available based on electrochemistry and patterned film growth on metal surface by anodic oxidation [18] or by galvanic displacement method [19], which are less complicated, avoids sev- eral steps and less cleaning procedure. Mueller et al., have studied the generation of MOFs via electrosynthesis in methanol medium [20] and also developed a series of MOFs using metal ion with var- ious linkers particularly terephthalic acid, naphthalene dicarbox- ylic acid and benzene tricarboxylic acid [21,22]. However, the above studies have limitation over the yield, particle size and sur- face area. Chui et al., reported that each of the four coordination sites of three Cu 2+ ions are bound to twelve carboxylate oxygen atoms of the two BTC ligands to form a face centered crystal lattice with Fm3m symmetry which possesses a three-dimensional chan- nel system with a bimodal pore size distribution based on their structural studies of Cu 3 (BTC) 2 [2]. Further, the above authors have calculated the copper–copper distance as 0.263 nm with a pore diameter of 0.9 nm were formed from 12 paddle-wheel subunits forming a cubic octahedron. The active copper species have free binding sites in the nano- spaces, which facilitate the formation of adducts with electroactive molecule. Such unique properties may provide benefits that make a Cu-MOF a good candidate for catalytic reaction. Cu 3 (BTC) 2 has widely been used as a heterogenous catalyst in acetalization of aldehydes with methonol [23], quinoline synthesis [24], a-pinene oxide rearrangement [25], trimethylsilylazide addition to carbonyl compounds [9], oxidation of benzylic compounds with t-butyl 1387-1811/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.micromeso.2012.09.028 ⇑ Corresponding author. Tel.: +91 4565 241550; fax: +91 4565 227713. E-mail address: manbu123@yahoo.com (M. Anbu Kulandainathan). Microporous and Mesoporous Materials 168 (2013) 57–64 Contents lists available at SciVerse ScienceDirect Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso