RESEARCH PAPER Graphene Oxide Nano-Sheets-Supported Co(II)-d-Penicillamine as a Green and Highly Selective Catalyst for Epoxidation of Styrene Sajjad Keshipour 1 • Mehran Kulaei 1 • Fatemeh Ahour 1 Received: 23 February 2017 / Accepted: 25 November 2017 Ó Shiraz University 2017 Abstract A new efficient heterogeneous catalyst was introduced for the epoxidation of styrene. The catalyst was obtained from functionalization of graphene oxide nano-sheets with d-penicillamine, and then complexation of graphene oxide func- tionalized d-penicillamine with Co(II). High yield and excellent selectivity were achieved for the epoxidation of styrene using the synthesized catalyst in solvent-free conditions at 50 °C using H 2 O 2 as a green oxidant during 2 h. The reaction has some advantages such as solvent-free and mild reaction conditions, high yield, excellent selectivity, green oxidant and short reaction conditions. Also, the recovered catalyst is applicable for 6 times without decrease in yield. Graphical Abstract Keywords Graphene oxide Á Nano-sheets Á Epoxidation Á Styrene oxide Á d-Penicillamine Á Heterogeneous catalyst 1 Introduction Carbon materials as catalysts are currently an active area of research due to biocompatibility and natural abundance of the catalyst (Su et al. 2013). Graphene oxide (GO) ((Loh et al. 2010a, b; Dreyer et al. 2014), as a new class of carbon support for the catalysts, has emerged for a wide range of synthetic transformations. GO is the exfoliated nano-sheets of distorted carbon networks carrying carboxylate, hydro- xyl, and other oxygen-containing functional groups. Gra- phene compounds have shown great promise for applications in different areas such as electronics, energy storage, and conversion as well as in the development of biosensors (Allen et al. 2009). Chemical modification of GO plays an important role in improving its properties for usage in various applications (Lomeda et al. 2008; Wang Ph Ph O H 2 O 2 , Solvent Free, 50 °C, 2h. (II) O O O OH COOH HO O HO HOOC HO HN O HO O SH Co 93% HOOC & Sajjad Keshipour s.keshipour@urmia.ac.ir 1 Department of Nanochemistry, Nanotechnology Research Centre, Urmia University, G. C., P. O. Box 165-5715944931, Urmia, Iran 123 Iran J Sci Technol Trans Sci https://doi.org/10.1007/s40995-017-0406-7