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Abstract: Novel S-doped Fe2O3/C nanocomposite was synthesized via a one-pot hydrothermal method and was used for the first time as an efficient adsorbent for Congo red dye (CR) removal from water solution. The obtained catalyst was characterized by various methods including Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, vibration sample magnetometry, X-ray diffraction and field emission scanning electron microscopy. To improve the adsorption performance, some important parameters affecting dye removal were optimized such as adsorbent dosage, contact time, solution pH, initial dye concentration and ionic strength. At the optimum conditions, the maximum capacity of adsorption for this nanocomposite was 270.2 mg g−1, which is better than other magnetic adsorbents for CR removal. The results of adsorption isotherm were matched with Langmuir model. Kinetic tests show that adsorption experimental data were best fitted by pseudo-first-order model.Graphical abstract: [ABSTRACT FROM AUTHOR]

Lanthanide-doped upconversion nanoparticles (UCNPs) have unique photoluminescent properties that are useful in many biomedical applications. Modification of UCNPs with a polymer layer can confer additional functionality such as biocompatibility, stability in vivo, or drug delivery capability. It is also important that the modification process can be controlled precisely and without having adverse effects on the UCNPs luminescence properties. Herein, a polymer shell was grafted directly from the surface of UCNPs (grafting from) via visible light (λmax = 635 nm, 0.7 mW/cm2) regulated photoenergy/electron transfer-reversible addition fragmentation chain transfer polymerization (PET-RAFT). The polymerization kinetics, grafting density, and thickness of the surface-tethered polymer chains can be tuned precisely by adjusting the monomer and RAFT agent ratio or the light exposure time. This approach also permits temporal control of the polymerization process. That is, the polymerization process can be initiated, halted, or terminated by switching the light source on and off. By limiting the non-radiative decay caused by surface defects, as well as from vibrational deactivation from solvents, the polymer shell enhanced the upconversion luminescence of the silica-coated UCNPs. This investigation paves the way for the development of UCNPs with controlled properties for various application requirements. [ABSTRACT FROM AUTHOR]

Highly dispersed Ni nanoparticles supported on high-surface-area mesoporous nanocrystalline MgAl2O4 powder was generated by a facile and simple propylene oxide assisted gelation agent route. The mesoporous spinel materials exhibited enhanced catalytic performance for hydrogen production in biogas dry reforming. The obtained spinel catalysts with different Ni loadings after calcination at 700 °C possessed high BET surface areas (236-224 m2 g−1). A narrow pore size distribution in the mesopore range was observed in the samples, and all the samples except 2.5 wt % Ni showed a mesoporous-macroporous structure. The 5 wt % Ni/MgAl2O4 sample showed the highest activity for the biogas dry reforming reaction because of the high dispersion of Ni on the mesoporous surface of the spinel support. X-ray photoelectron spectroscopy revealed that the catalysts with a low Ni loading undergo the exchange of Mg2+ by Ni2+, whereas catalysts with a higher Ni loading undergo the substitution of Al3+ by Ni3+. Thus, appropriate partial Ni substitution in the MgAl2O4 support may play a role in the elevated catalytic performance. [ABSTRACT FROM AUTHOR]

A bimetallic RhNi/Al 2 O 3 catalyst prepared by galvanic replacement (GR) offers enhanced catalytic CO 2 hydrogenation to selectively produce methane. • Galvanic replacement offers a facile route to bimetallic Rh@Ni core–shell catalysts. • Bimetallic Ni@Rh core–shell catalysts offer significant rate enhancements for CO 2 methanation. • Operando IR identifies reactively-formed CO as the key intermediate to CH 4 production. • Surface formate is a catalytic spectator in methanation. CO 2 utilisation as a chemical feedstock could transform fuels production and help mitigate climate change. Direct CO 2 reduction for energy production requires the development of active, stable, and low-cost catalysts selective for methane. A bimetallic Ni@Rh core–shell catalyst prepared by galvanic replacement (GR) exhibits a 3.5-fold rate enhancement for CO 2 methanation relative to an analogue prepared by chemical reduction (CR) and is twice as active as monometallic Rh/Al 2 O 3. Superior performance of RhNi/Al 2 O 3 (GR) is attributed to Rh dispersion as an atomically thin RhO x shell encapsulating Ni nanoparticles, stabilised by a strong Rh-Ni interaction. Operando IR spectroscopy identifies reactively-formed CO from the dissociative chemisorption of CO 2 over Rh as the key intermediate for methane production. Surface formate from the dissociative chemisorption of CO 2 and subsequent hydrogenation (via spillover from Rh sites) over alumina is a catalytic spectator. This mechanistic insight paves the way to high activity nanostructured catalysts for CO 2 methanation. [ABSTRACT FROM AUTHOR]

A facile one-step solution reaction route for growth of novel MoS2 nanorose cross-linked by 3D rGO network, in which the MoS2 nanorose is constructed by single-layered or few-layered MoS2 nanosheets, is presented. Due to the 3D assembled hierarchical architecture of the ultrathin MoS2 nanosheets and the interconnection of 3D rGO network, as well as the synergetic effects of MoS2 and rGO, the as-prepared MoS2-NR/rGO nanohybrids delivered high specific capacity, excellent cycling and good rate performance when evaluated as an anode material for lithium-ion batteries. Moreover, the nanohybrids also show excellent hydrogen-evolution catalytic activity and durability in an acidic medium, which is superior to MoS2 nanorose and their nanoparticles counterparts. [ABSTRACT FROM AUTHOR]

A green, robust and eco-friendly procedure for the oxidation of aromatic organic sulfides to sulfones using H 2 O 2 catalyzed by NH 2 -coordinately immobilized tris(8-quinolinolato)iron onto the silica coated magnetite (Fe 3 SiO 6 ) has been developed. Physicochemical properties of the resulting nanoparticles were investigated by means of techniques including X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, vibrating sample magnetometer, atomic adsorption spectroscopy and FT-IR spectroscopy. The catalytic activity of sulfides oxidation showed that this atom-economical protocol provided great yields of various sulfones and allowed the sulfide function reaction conducting under the mild conditions thus to prevent the sulfide being over-oxidized to sulfoxides. The Fe 3 O 4 @SiO 2 -FeQ 3 catalysts are magnetically separable and kept stable after recycling for 7 consecutive runs without detectable activity loss. [ABSTRACT FROM AUTHOR]

Three-dimensionally ordered macroporous (3DOM) CoFe 2 O 4 , z MnO x /3DOM CoFe 2 O 4 ( z = 4.99–12.30 wt%), and y Pd–Pt/6.70 wt% MnO x /3DOM CoFe 2 O 4 ( y = 0.44–1.81 wt%; Pd/Pt molar ratio = 2.1–2.2) have been prepared using the polymethyl methacrylate microspheres-templating, incipient wetness impregnation, and bubble-assisted polyvinyl alcohol-protected reduction strategies, respectively. All of the samples were characterized by means of various techniques. Catalytic performance of the samples was measured for methane combustion. It is shown that the as-prepared samples exhibited a high-quality 3DOM structure (103 ± 20 nm in pore size) and a surface area of 19–28 m 2 /g, and the noble metal or alloy nanoparticles (NPs) with a size of 2.2–3.0 nm were uniformly dispersed on the macropore wall surface of 3DOM CoFe 2 O 4 . The loading of MnO x on CoFe 2 O 4 gave rise to a slight increase in activity, however, the dispersion of Pd–Pt NPs on 6.70MnO x /3DOM CoFe 2 O 4 significantly enhanced the catalytic performance, with the 1.81Pd 2.1 Pt/6.70MnO x /3DOM CoFe 2 O 4 sample showing the highest activity ( T 10% = 255 °C, T 50% = 301 °C, and T 90% = 372 °C at a space velocity of 20,000 mL/(g h)). We believe that the excellent catalytic activity of 1.81Pd 2.1 Pt/6.70MnO x /3DOM CoFe 2 O 4 was related to its well-dispersed Pd–Pt alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between MnO x or Pd–Pt NPs and 3DOM CoFe 2 O 4 . [ABSTRACT FROM AUTHOR]

To overcome deactivation of Pd-based catalysts at high temperatures, we herein design a novel pathway by introducing a certain amount of CoO to the supported Au-Pd alloy nanoparticles (NPs) to generate high-performance Au-Pd-xCoO/three- dimensionally ordered macroporous (3DOM) Co3O4 (x is the Co/Pd molar ratio) catalysts. The doping of CoO induced the formation of PdO-CoO active sites, which was beneficial for the improvement in adsorption and activation of CH4 and catalytic performance. The Au-Pd- 0.40CoO/3DOM Co3O4 sample performed the best (T90% = 341 °C at a space velocity of 20--000 mL g-1 h-1). Deactivation of the 3DOM Co3O4-supported Au-Pd, Pd-CoO, and Au-Pd-xCoO nanocatalysts resulting from water vapor addition was due to the formation and accumulation of hydroxyl on the catalyst surface, whereas deactivation of the Pd-CoO/3DOM Co3O4 catalyst at high temperatures (680-800 °C) might be due to decomposition of the PdOy active phase into aggregated Pd0 NPs. The Au-Pd-xCoO/3DOM Co3O4 nanocatalysts exhibited better thermal stability and water tolerance ability compared to the 3DOM Co3O4-supported Au-Pd and Pd-CoO nanocatalysts. We believe that the supported Au-Pd-xCoO nanomaterials are promising catalysts in practical applications for organic combustion. [ABSTRACT FROM AUTHOR]

Three-dimensionally ordered mesoporous Co 3 O 4 ( meso -Co 3 O 4 ) and its supported Au, Pd, and Au–Pd alloy ( x Au y Pd/ meso -Co 3 O 4 ; x = 0.43–2.94 wt%; Au/Pd molar ratio ( y ) = 0.43–0.50) nanocatalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected reduction methods, respectively. It is found that the meso -Co 3 O 4 with a high surface area of 106 m 2 /g was cubic in crystal structure and the noble metal nanoparticles (NPs) with a size of 2.7–4.5 nm were uniformly dispersed on the surface of meso -Co 3 O 4 . The 2.94Au 0.50 Pd/ meso -Co 3 O 4 sample performed the best for methane combustion, showing the T 10% , T 50% , and T 90% (temperatures required for achieving methane conversions of 10%, 50%, and 90%) of 230, 280, and 324 °C at a space velocity of 20,000 mL/(g h) and the lowest apparent activation energy of 44.4 kJ/mol. Furthermore, the effects of CO 2 , SO 2 , and H 2 O addition on the catalytic stability of 2.94Au 0.50 Pd/ meso -Co 3 O 4 were also examined. It is concluded that the excellent catalytic performance of 2.94Au 0.50 Pd/ meso -Co 3 O 4 was associated with its porous structure, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Au–Pd alloy NPs and meso -Co 3 O 4 . [ABSTRACT FROM AUTHOR]

Highlights: [•] 3DOM La0.6Sr0.4MnO3 (LSMO) is prepared by polymethyl methacrylate-templating method. [•] xAu/LSMO catalysts are prepared by the polyvinyl alcohol-protected reduction method. [•] xAu/LSMO perform excellently in the oxidation of CO and toluene. [•] Activity is governed by Oads content, reducibility, and strong Au–LSMO interaction. [ABSTRACT FROM AUTHOR]