In recent decades, the environmental protection and long-term sustainability have become the focus of attention due to the increasing pollution generated by the intense industrialization. To overcome ...these issues, environmental catalysis has increasingly been used to solve the negative impact of pollutants emission on the global environment and human health. Supported platinum-metal-group (PGM) materials are commonly utilized as the state-of-the-art catalysts to eliminate gaseous pollutants but large quantities of PGMs are required. By comparison, single-atom site catalysts (SACs) have attracted much attention in catalysis owing to their 100% atom efficiency and unique catalytic performances towards various reactions. Over the past decade, we have witnessed burgeoning interests of SACs in heterogeneous catalysis. However, to the best of our knowledge, the systematic summary and analysis of SACs in catalytic elimination of environmental pollutants has not yet been reported. In this paper, we summarize and discuss the environmental catalysis applications of SACs. Particular focus was paid to automotive and stationary emission control, including model reaction (CO oxidation, NO reduction and hydrocarbon oxidation), overall reaction (three-way catalytic and diesel oxidation reaction), elimination of volatile organic compounds (formaldehyde, benzene, and toluene), and removal/decomposition of other pollutants (Hg
0
and SO
3
). Perspectives related to further challenges, directions and design strategies of single-atom site catalysts in environmental catalysis were also provided.
We report an Ag1 single‐atom catalyst (Ag1/MnO2), which was synthesized from thermal transformation of Ag nanoparticles (NPs) and surface reconstruction of MnO2. The evolution process of Ag NPs to ...single atoms is firstly revealed by various techniques, including in situ ETEM, in situ XRD and DFT calculations. The temperature‐induced surface reconstruction process from the MnO2 (211) to (310) lattice plane is critical to firmly confine the existing surface of Ag single atoms; that is, the thermal treatment and surface reconstruction of MnO2 is the driving force for the formation of single Ag atoms. The as‐obtained Ag1/MnO2 achieved 95.7 % Faradic efficiency at −0.85 V vs. RHE, and coupled with long‐term stability for electrochemical CO2 reduction reaction (CO2RR). DFT calculations indicated single Ag sites possessed high electronic density close to Fermi Level and could act exclusively as the active sites in the CO2RR. As a result, the Ag1/MnO2 catalyst demonstrated remarkable performance for the CO2RR, far surpassing the conventional Ag nanosized catalyst (AgNP/MnO2) and other reported Ag‐based catalysts.
Silver nanoparticles converted into single atoms bring about a significant improvement in electrocatalytic CO2 reduction with a 95.7 % faradic efficiency for CO production.
In this article, moisture-treated Pd@CeO2/Al2O3 and Pd/CeO2/Al2O3 catalysts were synthesized and applied in automotive three-way catalytic (TWC) reactions. Compared to the Pd/CeO2/Al2O3 catalyst, the ...Pd@CeO2/Al2O3 core–shell catalyst had better TWC activities. Transmission electron microscopy (TEM) images and X-ray photoelectron spectra (XPS) showed excess PdO2 on the Pd and CeO2 interface of Pd@CeO2 nanoparticles. Fourier transform infrared (FT-IR) spectra analysis demonstrated the generation of the hydroperoxyl (*OOH) groups on the surface of the Pd@CeO2 nanoparticle. CO-diffuse reflectance Fourier transform (DRIFT) measurement suggested that the CO adsorbed on *OOH species contributed to the formation of CO2 and intermediate *COOH. NO-DRIFT results showed that more *NO2 species appeared on the moisture-treated Pd@CeO2 nanoparticle, which was the main active site in the automobile TWC reaction. These were the main factors contributing to the moisture-treated Pd@CeO2/Al2O3 catalyst’s high catalytic activities. The collected data revealed the crucial role of the co-promoting effect of moisture and core–shell interface on TWC reactions over the Pd@CeO2/Al2O3 catalyst, which could be applied to other catalytic reactions.
A combination of large void volume and rich microporous structure enables expanded graphite (EG) to possess excellent adsorption properties. Furthermore, it is discovered to be hydrophilic with the ...capability of adsorbing NO
x
. The ball milling method was applied in preparation of the MnO
x
/TiO
2
modified by expanded graphite catalysts with the aim to improve SCR activity and resistance to H
2
O and SO
2
. An optimal SCR performance was obtained over the catalysts with 5 wt% EG doping. Subsequently, an investigation was conducted by XPS, NH
3
-TPD, H
2
-TPR into the understanding of the SCR catalytic performance of MnO
x
/TiO
2
at low-temperature. As revealed by the investigation results, the catalyst modified by EG had more Mn
4+
species and could absorb more oxygen, which allowed it to present more surface acid sites that could boost SCR activity. In addition, it was discovered that the introduction of EG could facilitate the improvement on the resistance to H
2
O and SO
2
.
Graphic Abstract
Expanded graphite (EG) has used to improve the SCR activity and resistance to H
2
O and SO
2
over the MnO
x
/TiO
2
. The catalyst with the addition of 5% EG was found to have more surface acid sites, surface adsorbed oxygen and Mn
4+
species.
A series of 2-3 nm Pt-Sn bimetallic nanoparticles with different Pt-Sn coordination numbers were synthesized by a stepwise approach including electrostatic adsorption and temperature-programmed ...reduction of metal precursors on the SiO2 support. In situ synchrotron XRD and XAFS demonstrated a highly ordered hexagonal Pt1Sn1 intermetallic shell on Pt nanoparticles. The turnover rates (TORs), propylene selectivity and stability of these bimetallic catalysts significantly surpass those of the monometallic Pt catalyst for propane dehydrogenation. At the same time, TORs increase with increasing Pt-Sn coordination number, whereas propylene selectivity is not significantly influenced by the Pt-Sn coordination number. Combined with experiments and theoretical calculations, the high propylene selectivity of the Pt-Sn bimetallic nanoparticles is attributed to the geometric effects of Sn that reduce the Pt ensembles, and the high TORs are due to the electronic effects that weaken Pt-hydrocarbon chemisorption energies.
In this paper, the hydrothermal stability and catalytic activity of Pd@Ce0.5Zr0.5O2/Al2O3 catalyst with a core–shell structure were investigated for automobile three-way reactions and compared with ...those of Pd/Al2O3, Pd@CeO2/Al2O3, and Pd@ZrO2/Al2O3 catalysts. TEM, HRTEM, and EDS mapping analyses showed that the core–shell structure of Pd@Ce0.5Zr0.5O2 nanoparticles was intact after the hydrothermal treatment at 1050 °C for 5 h. Meanwhile, CO–DRIFT results suggested that the interface of Pd core and Ce0.5Zr0.5O2 shell acted as the active sites in the reaction of three-way catalysts. Additionally, XPS, FT-IR, and CO–DRIFT analyses demonstrated that a large amount of OH groups were present on the surface of Pd@Ce0.5Zr0.5O2/Al2O3 catalyst, which could accelerate the decomposition of carbonate species and reduce the activation energy of the catalytic reaction. This was an important reason for the Pd@Ce0.5Zr0.5O2/Al2O3 catalyst to keep the high catalytic activity after aging at high temperature.
Rare earth metals are strategic resources with potential applications in optics, metallurgy and catalysis. In recent years, single-atom site catalysts (SASCs) have attracted increasing attention ...owing to their 100% atom efficiency and unique catalytic performances. Over the past decade, rare earth elements, including rare earth metals and their oxides, have shown great potential in SASCs. However, systematic analyses of data are still handful. In this mini-review, the use of rare earth metals and their oxides in SASCs was summarized and the results are discussed. A particular focus was paid to the synthetic strategies, characterization of rare earth-containing SASCs, and applications as catalysis supports, promoters and active sites. Current issues faced by rare-earth metals and their oxides in SASCs, as well as future prospects were also provided.
A review about the use of rare earth elements in single-atom site catalysis. Display omitted
An error appeared in our paper entitled “
The Keggin Structure: An Important Factor in Governing NH
3
–SCR Activity Over the V
2
O
5
–MoO
3
/
TiO
2
Catalyst
” published in
Catalysis Letters
. We used ...a wrong icon in Fig. 8. The black line should be “Cat-A-V” and the red line should be “Cat-B-V”. The corrected Fig. 8 is shown below.
A novel nitrogen-riched composite (PPYTZ/C) was firstly prepared by chemical polymerization, and then the Cu-PPYTZ/C complex was obtained by immersing the PPYTZ/C modified electrode in copper ...sulphate solution. For comparing the performance of the two catalysts, physical and electrochemical measurements were adopted. Wherein, physical measurements include scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). And, the electrochemical measurements include cyclic voltammetry (CV), rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE), and then the above measurement results were compared with commercial Pt/C. The CV and RDE results proved that Cu-PPYTZ/C catalyst exhibits excellent performance than that of PPYTZ/C in term of ORR activities and stability. In addition, the RRDE results also indicated that Cu-PPYTZ/C is comparable to the commercialization Pt/C in term of electron transfer numbers. In conclusion, Cu-PPYTZ/C is the potential candidate for oxygen reduction reaction catalysts, which is attribute to the role of CN
x
-M in Cu-PPYTZ/C catalyst as the catalytic group.
Graphic Abstract
Supported metal-group materials are commonly utilized as state-of-the-art catalysts in industry. Atomic-sites catalysts (ASCs) have attracted increasing attention in catalysis owing to their 100% ...atom efficiency and unique catalytic performances toward various reactions. In particular, atomic dispersion of bulk and nano metals has become the focus of research and development in the synthesis of ASCs. Over the past decade, burgeoning interests have been paid to atomic dispersion in ASCs and their applications in catalysis. However, to the best of our knowledge, the systematic summary and analysis of atomic dispersion were rarely reported. In this review, recently developed ASCs by atomic dispersion were discussed in terms of synthetic atmosphere, driving force, and applications in thermal catalytic reactions. Perspectives related to challenges and directions as well as design strategies of ASCs in atomic dispersion were also provided.
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