The samples were applied later on the hydrogenation of styrene (Figure 1) for a comparison with results from the commercially available activated carbon-supported Pd and Pt catalysts, Pt/C and Pd/C. Figure 1 The hydrogenation reaction of styrene to ethylbenzene and ethylcyclohexane. Methods The synthesis of graphite oxide and graphene followed the well-known Hammer’s method [25]. A 250-mL round bottomed flask filled with 25 mL concentrated sulfuric acid (98%, Adrich, St. Kinase Inhibitor Library Louis, MO, USA) was held in an iced bath. After 5 to 10 min, 10 mL fumed nitric acid was added slowly in 15 min. Then, graphite powder (1.0 g, with particle size <45 μm) was added into the mixture under vigorous stirring for

30 min with the flask held in the iced bath. Then 22 g potassium chlorate was added into the solution in 30 min, and the mixture was stirred at room temperature for 96 h. The solution was centrifuged with a suitable

amount (about 200 to 300 mL) of deionized (DI) water added under an iced bath temperature. Removal of liquid phase, followed by addition of DI water and then centrifugation, was repeated for three times. The mud-like residue was dried at 80°C for 12 h to produce the graphite oxide. The nanocomposite Z-IETD-FMK synthesis followed a procedure similar to that reported in our previous study [26]. Graphite oxide (250 mg) was added in 250 mL DI water and stirred for 30 min before addition of 1.4 g NaBH4, and the mixture was kept at 80°C for 1 h. Prior to sulfonation, the solution was centrifuged for collection of residues that were rinsed with methanol for three times then dried at 80°C under the N2 atmosphere for 1 h. The graphite oxide was sulfonated and exfoliated to graphene with the following procedure: in a 500-mL round-bottomed flask, the residues old (158 mg) in 300 mL DI water were dispersed using an ultrasonic bath for 30 min. Separately,

sulfanilic acid (140 mg) and potassium nitrate (50 mg) were introduced into a 100-mL beaker containing DI water (40 mL) employing an iced bath. After being mixed well, the solution was added with 1 N HCl (1 mL) and then the solution was poured into the above mentioned round-bottomed flask and stirred for 2 h in the iced bath. Centrifugation followed by removal of aqueous solution resulted in the sulfonated graphene, which was rinsed with methanol for a few times then dried at 80°C under the N2 atmosphere. The microwave-assisted synthesis of Pt/GE and Pt/GO was performed using a CEM Discover Du7046 microwave set (Matthews, NC, USA) with 80 W power output for 30 s then held at 80°C for 5 min. The nanocomposites were prepared with sulfonated graphene or graphite oxide (100 mg) as substrates together with grinded K2PtCl6 at 14.5, 355, or 15 mg, respectively, plus 2-hydroxyethanaminium formate (5.0 g), in Pyrex glass tubes (results shown in Table 1).