High-Performance Ag–Cu Nanoalloy Catalyst for the Selective Catalytic Oxidation of Ammonia

Abstract

High-performance Ag–Cu alloy nanoparticles (NPs) were successfully synthesized by a solventless mix–bake–wash method and tested for NH3-SCO. The prepared Ag2Cu1 catalyst with a perfect Ag–Cu alloy structure exhibited better T 100 (200 °C, the temperature at which 100% NH3 conversion was obtained), higher reaction rates, and lower E a compared to that with ordinary bimetallic Ag–Cu (AgCuO x ). The characterization data revealed much smaller Ag–Cu alloy nanoparticles of the Ag2Cu1 catalyst and more Ag/Cu metallic species on the surface, which can increase the amount of chemisorbed surface oxygen (Oβ) and enhance NH3 adsorption and activation in the low-temperature range, therefore leading to a much higher NH3-SCO activity. Kinetic studies and density functional theory calculations indicated that Cu decoration at Ag by Ag–Cu alloying could enhance the adsorption/activation of NH3 and O2. It has been found that O2 was more easily transformed from the adsorption state to the transition state than NH3, which enhanced the performance of NH3 oxidation. In addition, the Ag2Cu1 catalyst exhibited excellent durability because of the stabilization of Ag sites by the Ag–Cu alloy structure.

Oxidative Esterification of 5‐Hydroxymethylfurfural with an N‐doped Carbon‐supported CoCu Bimetallic Catalyst

“…As X‐ray diffraction (XRD) patterns shown (Figure ), there are no diffractive peak of metallic Co specie in all Co x Cu y ‐NC catalysts, which indicates that Co species are well‐dispersed in the catalysts. Furthermore, typical metallic Cu peaks can be identified in those Cu containing catalysts and the size of Cu particles decreased from 32 nm in Cu‐NC to 16 nm in Co 7 Cu 3 ‐NC.This finding suggests that the dispersity of Cu was improved after being introduced into Co‐NC, probably because of the interaction between Cu and Co…”

Antimicrobial Properties of the Ag, Cu Nanoparticle System

“…A second study, on Cu 2 O-Ag nanocomposites, reached a similar conclusion [271]. If Ag and Cu formed a homogeneously distributed nanoalloy microstructure, the diffraction peaks of Cu and Cu oxides would not appear in the XRD (Figure 20a,b) [272]. On the contrary, the presence of the diffraction peaks of Cu and Cu oxides in the spectrum indicated that the phases are separated (Figure 20c,d) [272].…”

“…If Ag and Cu formed a homogeneously distributed nanoalloy microstructure, the diffraction peaks of Cu and Cu oxides would not appear in the XRD (Figure 20a,b) [272]. On the contrary, the presence of the diffraction peaks of Cu and Cu oxides in the spectrum indicated that the phases are separated (Figure 20c,d) [272]. The formation of oxide-free AgCu nanoalloys can also be determined by XRD, through the absence of the CuO diffraction peak at 61.…”

Highly effective adsorption removal of perfluorooctanoic acid (PFOA) from aqueous solution using calcined layer-like Mg-Al hydrotalcites nanosheets

“…Nowadays, more and more pollutants have attracted the attention (Wang et al 2019a;Wang et al 2019b;Wang et al 2020;Zhang et al 2019;Zhang et al 2020a;Zhang et al 2020b;Zhou et al 2019). Among them, the perfluorinated compounds (PFCs), as a persistent organic pollutant, is investigated by more and more researchers.…”