Catalytic Degradation of 4-Nitrophenol in Polluted Water by Three-Dimensional Gold Nanoparticles/Reduced Graphene Oxide Microspheres

Abstract

Microspheres as catalysts catalyst supports have attracted a great deal of attention over the last two decades. Here, gold nanoparticles (Au-NPs) encapsulated within the reduced graphene oxide microspheres (rGO microspheres) were prepared by using a spray-drying method. The Au-NPs were distributed evenly through the rGO microsphere composite. The mass content of Au-NPs in the rGO microspheres composite reached 30.3%, and the average size of the Au-NPs was 10.5±2.5 nm. The morphologies and structural characteristics of the materials were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) patterns. The as-prepared composite was used to catalyze the reduction of 4-nitrophenol to 4-aminophenol in the presence of excess sodium borohydride and exhibited high catalytic activity. The catalysis process was monitored by UV spectroscopy, and the −3-1 4 first order rate constant of the catalytic reaction K was 1.96×10 s , and the activation energy E was found to be 3.5×10 J/mol. The catalytic a experiment results indicated the Au/rGO microspheres prepared have a great application for friendly environment aspects.

Exfoliation Energy as a Descriptor of MXenes Synthesizability and Surface Chemical Activity

“…Since their first isolation in 2011 [ 1 ], MXenes, a new family of two-dimensional (2D) layered materials, have constituted an incredibly growing hub of research on different fields of technology; from materials for Lithium batteries [ 2 , 3 ] to supercapacitors [ 4 , 5 ], electromagnetic interference shielding materials [ 6 , 7 , 8 ], and uses as heterogeneous catalysts [ 9 , 10 , 11 ] or biosensors [ 12 , 13 ], to name a few. Indeed, MXenes are part of the post-graphene 2D materials, which still offer new examples and applications, e.g., for CO 2 utilization [ 14 ], as catalysts [ 15 ], or as new thermoelectric materials [ 16 ], to cite some. A particularly appealing field is the use of MXenes in environment-related applications, e.g., pristine MXenes, have been first theoretically [ 17 ] and later experimentally [ 18 ] appointed to be well-suited materials for carbon dioxide (CO 2 ) greenhouse gas abatement, with CO 2 uptakes an order of magnitude larger than other tested porous materials.…”

Efficient Photodegradation of Eriochrome Black-T by a Trimetallic Magnetic Self-Synthesized Nanophotocatalyst Based on Zn/Au/Fe-Embedded Poly(vinyl alcohol)

“…The distinguished peaks corresponding to lattice planes (1 0 0), (0 0 2), (1 0 1), (1 0 2), (1 1 0), (1 0 3), (1 1 2), and (2 0 1) at 30.7, 34.2, 35.3, 46.7, 54.7, 62.0, 66.2, and 66.8°, respectively, show that the synthesized ZnO NRs demonstrated good crystallinity with a hexagonal structure and matched with JCPDS card number 01-075-1533 (Figure b­(ii)) . The XRD pattern of Fe 3 O 4 @PVA-Au magnetic nanocomposite is presented in Figure b­(iii), which displays four peaks at 38.4, 44.6, 64.8, and 77.9° attributed to the (1 1 1), (2 0 0), (2 2 0), and (3 1 1) crystal faces of the face-centered cubic structure of crystalline Au NPs, respectively . More importantly, Figure b­(iv) representing the Fe 3 O 4 @PVA–Au/ZnO magnetic photocatalytic system shows all of the prominent peaks of the individual components.…”

Flower-like Hydroxyfluoride-Sensing Platform toward NO2 Detection

“…Nitrogen dioxide (NO 2 ), mainly released from vehicles and industries, is one of the most widespread pollutants in the world. − It can not only cause many environmental issues like photochemical smog and acid rain but also seriously threaten human health as it can cause some respiratory diseases, such as bronchitis and pulmonary edema, and can cause death in severe cases. − As such, it is highly desirable to develop devices that could efficiently detect low-concentration NO 2 to provide timely alerts to people. As the most effective gas-detecting method, resistive gas sensors have been used in many fields, like atmospheric monitoring, gas leak detection, etc. − Recently, resistive gas sensors based on metal oxide semiconductors (MOSs) have been widely applied owing to their merits of high efficiency, simple operation, easy fabrication procedures, miniaturization, and low production cost .…”