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Precious metal nanoparticles, especially Ag-based nanoparticles due to their strong surface plasma effect and excellent catalytic performance, have been widely applied in environmental remediation and detection of heavy metal ions in aqueous solution. In this study, first, bimetallic Ag/Co nanoparticles (Ag/Co NPs) modified by sodium citrate were synthesized by chemical reduction method. Second, bimetallic Ag/Co NPs were used as colorimetric probe for detecting Cr 3 + and Fe 3 + in aqueous solution simultaneously for the first time. The results showed that the probe had high specificity towards Cr 3 + and Fe 3 + among the tested metal ions. When Cr 3 + was mixed with Ag/Co NPs, the solution quickly changed from yellow to pink, meanwhile, the UV–Vis absorption intensity declined at 400 nm and a new prominent absorption band was formed at 530 nm. While Fe 3 + was mixed with Ag/Co NPs, the solution quickly changed from yellow to nearly colorless. The linear relationship between absorbance of bimetallic Ag/Co NPs at 400 nm and −log of Cr 3 + concentration is 1 nM to 10 μ M, which y = 0. 0 0 8 4 x + 1. 5 0 1 2 and R 2 = 0. 9 8 5 5. The limit of detection (LOD) for this study was 1.14 nM. Similar to Cr 3 + , the LOD for Fe 3 + was calculated 16.3 μ M. In addition, the catalytic performance of bimetallic Ag/Co NPs was evaluated by methylene blue (MB) in the presence of H2O2. The catalytic degradation efficiency of bimetallic Ag/Co NPs was about 4.8 times greater than monometallic Ag NPs, confirming Ag and Co NPs had obviously synergistic effect. Therefore, this result made bimetallic Ag/Co NPs had potential application in the field of environmental remediation. Bimetallic Ag/Co nanoparticles (NPs) modified by sodium citrate were synthesized by chemical reduction method. The prepared Ag/Co NPs were used as a colorimetric probe for detecting Cr3+ and Fe3+ in aqueous solution simultaneously for the first time. Furthermore, the catalytic performance of bimetallic Ag/Co NPs was evaluated by methylene blue in the presence of H2O2. The catalytic degradation efficency of bimetallic Ag/Co NPs was 4.8 times greater than monometallic Ag NPs, confirming that Ag and Co NPs have a synergistic effect. [ABSTRACT FROM AUTHOR]

A hierarchical porous zeolite Y (HPZY) supported Ni–Co catalyst was prepared by pyrolyzing nickel tetracarbonyl and using modified deposition-precipitation to highly disperse Ni–Co nanoparticles onto HPZY. Hecaogou subbituminous coal was effectively ethanolyzed to obtain ethanol-soluble portion (ESP E) in a high yield (21.2%). Sequentially, ESP E was subjected to the deep hydroconversion (DHC) over prepared Ni 10% -Co 3% /HPZY at 150 °C under 4 MPa of initial hydrogen pressure for 24 h in n -heptane to produce deeply hydroconverted ethanol-soluble portion (ESP DHC). All the group components in ESP E , including arenes (53.3%), oxygen-containing organic compounds (24.4%), and nitrogen-containing aromatics (2.3%) were completely converted to chain alkanes (CAs, 36.8%), cyclanes (39.2%), and hydroarenes (24.0%). In addition, the hydroisomerization of CAs and hydroreforming of aromatic rings (ARs) in ESP DHC are predominant over Ni 10% -Co 3% /HPZY with more accessibility of active sites under mild conditions. Ni 10% -Co 3% /HPZY with suitable acidity and highly dispersed Ni–Co nanoparticles can effectively activate H 2 to H⋯H and further heterogeneously split H⋯H to H+ and H−. H⋯H and H+ transfer plays crucial roles in the DHC of ESP E. Correspondingly, the related mechanisms are evidenced by the DHC of 2,2′-oxydinaphthalene (ODN) over Ni–Co/HPZY. Ni 10% -Co 3% /HPZY maintains high activity for the DHC of ODN under mild conditions after 4 recycles. • Modify CZY by fluorine-alkaline cascaded treatment to obtain HPZY. • Ni–Co/HPZY has an outstanding catalytic activity and stability for the DHC of ESP E. • Ni–Co/HPZY effectively induced the formation of H+, H−, and H⋯H during the DHC. • All of group components in ESP E were completely converted to CAs, cyclanes, and HAsII. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ag-Co nanoparticles with rich catalytic sites are effectively decorated on Fe 3 O 4 @EDTA by co-reducing agent in-situ deposition method for the first time. • The Ag-Co@EDTA@Fe 3 O 4 NPs expressed high saturation magnetization. • The enhanced catalytic activity of Ag-Co@EDTA@Fe 3 O 4 NPs towards 2-nitrophenol reduction was explored. • The hydrodynamic diameter of Ag-Co@EDTA@Fe 3 O 4 NPs was unobviously increased after 5 cycle times. In this study, firstly, bimetallic Ag-Co nanoparticles with rich catalytic sites decorated on Fe 3 O 4 magnetic carriers through metal ion chelating agent EDTA (Ag-Co@EDTA@Fe 3 O 4 NPs) were fabricated by co-reducing agent in-situ deposition method for the first time. The synthesized nanocomposites were characterized by various techniques, including UV–vis, XRD, TEM, EDX, XPS and VSM. Secondly, the catalytic reduction performance of Ag-Co@EDTA@Fe 3 O 4 NPs was analyzed for 2-nitrophenol in the presence of NaBH 4 at 25 ℃. Results showed that the k of Ag-Co@EDTA@Fe 3 O 4 NPs was 10.9 and 2.7 times higher than that of Co@EDTA@Fe 3 O 4 and Ag@EDTA@Fe 3 O 4 NPs, respectively, which considered to obey the first-order kinetics equation, proving the strong synergistic effect between Ag and Co nanoparticles. Furthermore, the significantly enhanced catalytic activity of Ag-Co@EDTA@Fe 3 O 4 NPs was discussed. Plenty of Ag NPs were successfully anchored on Fe 3 O 4 @EDTA supports maybe the crucial factor, and the doped Co provided much more active sites in the catalytic process. Finally, the degradation efficiency of Ag-Co@EDTA@Fe 3 O 4 NPs still remained above 95% after 5 cycles. Importantly, there was no significant difference between the fresh catalyst and after cycling for 5 times, observed by TEM and SEM. Meanwhile, the change of hydrodynamic diameter of the used Ag-Co@EDTA@Fe 3 O 4 NPs over cycle number was measured around 230 nm which increased unobviously, making it a promising candidate for wastewater treatment in industries. [ABSTRACT FROM AUTHOR]

• Large amounts of smaller Ag nanoparticles were successfully anchored into/onto the hollow-porous Fe 3 O 4 MMPs by a novel thermal co-reduction method. • The Fe 3 O 4 /Ag MMPs exhibited high saturation magnetization. • The enhanced catalytic properties of Fe 3 O 4 /Ag MMPs were explored. In this report, a highly dispersity and smaller size of Ag nanoparticles were directly embedded into/onto the hollow-porous Fe 3 O 4 magnetic microspheres (Fe 3 O 4 /Ag MMPs) by a novel thermal co-reduction method, which used both NaBH 4 and trisodium citrate dihydrate as reducing agent to reduce the AgNO 3 to Ag nanoparticles. The structural, morphological and magnetic properties of the obtained Fe 3 O 4 and Fe 3 O 4 /Ag MMPs were characterized by various techniques, including FT-IR, XRD, XPS, FE-SEM, TEM, VSM and so on. The catalytic performance of Fe 3 O 4 /Ag MMPs was examined towards the reduction of p-nitroaniline into p-phenylenediamine in fresh NaBH 4 solution, which employing UV–vis spectrophotometer at 380 nm to continuously monitor the reaction progress. The characterization and experimental results indicated that Ag nanoparticles were successfully anchored both in the inner and outer of the hollow-porous Fe 3 O 4 magnetic supports with a weight percent of 31.33%, in addition, the Fe 3 O 4 /Ag MMPs remained a high saturation magnetization value of 50.53 emu/g. More importantly, Fe 3 O 4 /Ag MMPs had excellent catalytic reduction properties, which fitted well with the first-order kinetics equation and the corresponding apparent rate constant k was 0.45 min−1. The enhanced catalytic properties of Fe 3 O 4 /Ag MMPs may be ascribed to the numerous loading of Ag nanoparticles, which were highly monodispersed and stable in an aqueous solution, as well as the remarkable synergistic effect between Ag nanoparticles and hollow-porous Fe 3 O 4 magnetic microspheres. [ABSTRACT FROM AUTHOR]