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Graphical abstract Highlights • Ozone-assisted catalysis was able to remove CO efficiently at room temperature. • Bimetallic Ag-Pd catalyst exhibited a cooperative effect. • In situ FTIR measurement provided useful insights into the mechanism of the catalytic reaction. Abstract The room-temperature oxidation of CO using ozone-assisted catalysis (OAC) over monometallic or bimetallic catalysts supported on γ-Al 2 O 3 is presented. Within the tested particle size range, ozone decomposition was insensitive to the size of the Ag particles (6.6–11.9 nm) at weight hourly space velocities of up to 360 L·g−1·h−1. Among the tested monometallic catalysts (Ag Pd, Fe, Mn, and Cu), Ag showed the highest activity for CO oxidation. Bimetallic catalysts (Ag-M or Pd-M where M = Cu, La, Ru, and Fe) were also considered by adding a second metal or perovskite oxide (LaFeO 3) to Ag. A cooperative effect was observed with the bimetallic Ag-Pd catalyst for the OAC of CO oxidation at room temperature, whereas the other bimetallic catalysts showed slightly lower performance compared to the monometallic catalyst. A high ozone utilization efficiency of 0.94 was achieved with the bimetallic Ag-Pd/γ-Al 2 O 3 catalyst. High-angle annular dark-field scanning tunneling electron microscopy (HAADF) and energy dispersive X-ray (EDX) spectroscopy measurements confirmed the proximity of the two components, which is essential for their interaction. The in situ FTIR measurements revealed that the cooperative effect in the bimetallic Ag-Pd catalyst involved modification of CO adsorption and the suppression of product accumulation. Two typical IR absorption bands of linear- (2090 cm−1) and bridge-CO (1918 cm−1) on Pd disappeared in the presence of Ag nanoparticles. Thus, the presence of Ag in contact with Pd inhibited the accumulation of carbonates, which led to enhanced catalytic performance. Adsorption site-dependent CO oxidation on Pd was also confirmed by the in situ Fourier transform IR measurement. [ABSTRACT FROM AUTHOR]

Abstract: A series of model bimetallic Pd-Ag catalysts with different ratios of metals and size distributions of supported particles was prepared by successive metal deposition onto a modified surface of highly oriented pyrolytic graphite (HOPG). X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) were used to characterize the structural and electronic properties, as well as the morphology of nanoparticles at all stages of catalyst preparation. The use of the method made it possible to obtain bimetallic particles with various structures: alloyed, core-shell, and those consisting of individual monometallic particles. The XPS method with synchrotron radiation was used to determine the patterns in the formation of alloyed bimetallic particles, their chemical composition, structure, and the ranges of thermal stability under conditions of ultrahigh vacuum. [ABSTRACT FROM AUTHOR]

Au-Pd supported on ceria-zirconia catalysts, with Au:Pd molar ratios in the 1:1-10:1 range, have been prepared using deposition precipitation of Au followed by impregnation with Pd. The resulting Au-Pd supported catalysts were activated by oxidation at 350, 450 and 700 °C. The oxidation at 700 °C led to the formation of large Au-Pd alloy nanoparticles showing lower catalytic activity for CO oxidation. The Au-Pd/CeZrO catalyst with the highest Au:Pd ratio, 10:1, exhibited the highest CO oxidation activity. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Porous bimetallic alloyed palladium silver (PdAg) nanoflowers supported on reduced graphene oxide (PdAg NFs/rGO) were prepared via a facile and simple in situ reduction process, with the assistance of cetyltrimethylammonium bromide as a structure directing agent. The as-prepared nanocomposite modified glassy carbon electrode (PdAg NFs/rGO/GCE) showed enhanced catalytic currents and enlarged peak potential separations for the oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA) as compared to those of PdAg/GCE, rGO/GCE, commercial Pd/C/GCE, and bare GCE. The as-developed sensor can selectively detect AA, DA, and UA with a good anti-interference ability, wide concentration ranges of 1.0 μM–2.1 mM, 0.4–96.0 μM, and 1.0–150.0 μM, respectively, together with low detection limits of 0.057, 0.048, and 0.081 μM (S/N = 3), respectively. For simultaneous detection of AA, DA, and UA, the linear current–concentration responses were observed from 1.0 μM–4.1 mM, 0.05–112.0 μM, and 3.0–186.0 μM, with the detection limits of 0.185, 0.017, and 0.654 μM (S/N = 3), respectively. [ABSTRACT FROM AUTHOR]

Highly dispersed bimetallic AgPd nanoparticles with different composition have been successfully deposited on the metal-organic frameworks (ZIF-8) by using a simple liquid impregnation method. The resultant catalysts are composition dependent toward dehydrogenation of formic acid, while Ag 18 Pd 82 @ZIF-8 exhibits exceedingly high catalytic activity, with the turnover frequency (TOF) value of 580 h −1 , and 100% hydrogen selectivity at 80 °C. [ABSTRACT FROM AUTHOR]

Monodispersed bimetallic PdAg nanoparticles can be fabricated through the emulsion-assisted ethylene glycol (EG) ternary system. Different compositions of bimetallic PdAg nanoparticles, Pd80Ag20, Pd65Ag35 and Pd46Ag54 can be obtained via adjusting the reaction parameters. For the formation process of the bimetallic PdAg nanoparticles, there have two-stage growth processes: firstly, nucleation and growth of the primary nanoclusters; secondly, formation of the secondary nanoparticles with the size-selection and relax process via the coalescence or aggregation of the primary nanoclusters. The as-prepared PdAg can be supported on the carbon black without any post-treatment, which exhibited high electro-oxidation activity towards methanol oxidation under alkaline media. More importantly, carbon-supported Pd80Ag20 nanoparticles reveal distinctly superior activities for the methanol oxidation, even if compared with commercial Pt/C electro-catalyst. It is concluded that the enhanced activity is dependant on the unique twinning structure with heterogeneous phase due to the dominating coalescence growth in EG ternary system. [ABSTRACT FROM AUTHOR]

Small-sized monodisperse Pd-Ag alloy nanocrystals (NCs) are synthesized via a solid-liquid and solid-solid phase chemical route, i.e., sequential reduction of Pd(NO3)2 and AgNO3 solid precursors in the liquid mixture of dodecylamine and 1-octadecene, followed by fusion of formed Pd and Ag NCs at 250 °C. By controlling the addition sequence and molar ratio of the metallic precursors, a series of Pd-Ag alloy NCs, including Pd5Ag, Pd2Ag, PdAg, PdAg2, and PdAg5, is obtained. The alloy NCs are highly crystallized and exhibit a strong atomic ensemble in addition to component-dependent electronic effects. Pd2Ag NCs have unique structure and electronic properties, showing a much faster electron transfer process at a modified glassy carbon electrode interface compared with that of other alloys. Therefore, the Pd2Ag NCs are chosen as the electrocatalyst to evaluate the performance of Pd-Ag nanoalloy and a novel non-enzymatic glucose biosensor is fabricated. The biosensor exhibits an acceptable reproducibility, a good stability and low interferences, which can be used to examine glucose in clinic blood serum samples. This work provides a simple multiphasic reaction system to synthesize binary alloy NCs with well-controlled componential ratio and opens the avenue to utilize them in biosensing or other advanced technological fields. [ABSTRACT FROM AUTHOR]