Preparation of Reduced-Graphene-Oxide-Supported CoPt and Ag Nanoparticles for the Catalytic Reduction of 4-Nitrophenol

Abstract

Composite nanostructure materials are widely used in catalysis. They exhibit several characteristics, such as the unique structural advantage and the synergism among their components, which significantly enhances their catalytic performance. In this work, CoPt nanoparticles and reduced-graphene-oxide-based nanocomposite catalysts (rGO/CoPt, rGO/CoPt/Ag) were prepared by using a facile co-reduction strategy. The crystalline structure, morphology, composition, and optical characteristics of the CoPt nanoparticles, rGO/CoPt nanocomposite, and rGO/CoPt/Ag nanocomposite catalysts were investigated by a set of techniques. The ID/IG value of the rGO/CoPt/Ag nanocomposite is 1.158, higher than that of rGO/CoPt (1.042). The kinetic apparent rate constant, k, of the rGO/CoPt/Ag nanocomposite against 4-nitrophenol (4-NP) reduction is 5.306 min−1, which is higher than that of CoPt (0.495 min−1) and rGO/CoPt (1.283 min−1). The normalized rate constant, knor, of the rGO/CoPt/Ag nanocomposite is 56.76 min−1mg−1, which is higher than some other catalytic materials. The rGO/CoPt/Ag nanocomposite shows a significantly enhanced catalytic performance when compared to CoPt nanoparticles and the rGO/CoPt nanocomposite, which may confirm that the novel rGO/CoPt/Ag nanocomposite is a promising catalyst for the application of catalytic fields.

Effect of the Preparation Conditions on the Catalytic Properties of CoPt for Highly Efficient 4-Nitrophenol Reduction

“…CoPt, rGO/CoPt, and rGO/CoPt/Ag catalysts showed a reduction time of 8, 4, and 1 min [15]. A volume of 0.1 mL of 4-NP, 0.005 mol/L and 2 mL of deionized water was added to the quartz cuvette.…”

“…The CoPt alloys are one of the most studied materials due to their possible applications in BPM (Bit Patterned Media) for high-density magnetic recording [9,10], microelectromechanical systems (MEMS) for sensing and actuating devices [9,11], Magnetic Resonance Imaging (MRI) contrast agents [1,12], or as catalysts [13][14][15][16].…”

“…In the field of catalysis, the CoPt alloy has been widely studied in the last years for possible application as a catalyst for a Fisher-Tropsch reaction [17], imines synthesis [18], carbon nanotubes and nanofibers preparation [19,20], Li-O 2 batteries [21], hydrogen generation [22][23][24][25], Oxygen Reduction Reaction [26,27], Methanol Oxidation Reaction [28][29][30][31] as well as for the catalytic reduction of 4-Nitrophenol [15,32]. The most used synthesis route for CoPt alloy preparation is chemical reductions [33] and electrochemical deposition [11,31,[34][35][36].…”

Facile Synthesis of CoOOH Nanorings over Reduced Graphene Oxide and Their Application in the Reduction of p-Nitrophenol

“…The high specific surface area of rGO is beneficial for the loading of nanoparticles, thus improving the dispersion of particles on rGO nanosheets [34]. Moreover, many studies have demonstrated the presence of a synergistic effect between rGO and the anchoring particles, which can significantly enhance the catalytic performance [35,36]. For example, Co 3 O 4 nanocrystals grown on rGO showed surprisingly high catalytic activity for oxygen reduction reaction and oxygen evolution reaction because of the synergetic chemical coupling effects between Co 3 O 4 nanocrystals and graphene [37].…”

“…The CoOOH/rGO nanocomposite served as the catalyst to relay active hydrogen species and electrons from the adsorbed donor (BH 4 − ) to the adsorbed acceptor (p-NP) nearby, thereby triggering the reduction reaction. Therefore, the efficient adsorption performance for p-NP and BH 4 − as well as its excellent electron transport ability, are the key factors for a catalyst to have superior activity [36]. In addition, Qu et al have demonstrated that, for the catalytic hydrogenation of p-NP, increasing the amount of reactants adsorbed on the catalyst surface is beneficial in improving the catalytic performance [47].…”