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.
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.
Display omitted
•Pt/MnOx and Pt/MnO electrocatalysts were prepared for the oxygen reduction reaction.•Pt-based electrocatalysts showed high utilization efficiency of Pt.•Both Pt-based catalysts ...exhibited good ORR stability.
Electrocatalyst for oxygen-reduction reaction (ORR) is crucial for metal-air batteries, in which Pt-based materials are the benchmark catalysts for ORR. However, the high cost and limited supplies of Pt limit its broad use in commercial applications. Designing highly efficient Pt electrocatalysts can reduce material cost and enable commercial success for a wide variety of electrochemical technologies. Herein, we prepared Pt/MnOx and Pt/MnO electrocatalysts via deposition–precipitation and H2–reduction approaches. The Pt mass activities towards the ORR at 0.7 V for the Pt/MnOx, and Pt/MnO catalysts were 4.0 and 3.7 A mgPt−1, respectively, which were 20, and 18.5 times as commercial 20% Pt/C catalyst. The transferred electron numbers (n) were 3.6 and 4.0 for Pt/MnOx and Pt/MnO, respectively. Moreover, Pt/MnO catalyst exhibited a good ORR stability after 500 cycles compared to Pt/MnOx catalyst in 0.1 M KOH.
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.
Partial oxidation of methane (POM) is a potential technology to increase the efficiency of synthesizing a mixture of CO and H2 called syngas, in comparison to steam reforming processes. Recently, ...supported metals modified with Re have emerged as active catalysts for POM. However, the role of Re in this reaction has been unclear. Here, we demonstrate that the addition of Re to a Ru/Al2O3 catalyst changes the reaction mechanism. The bimetallic catalyst oxidizes CH4 to mainly CO via formate. After all of the O2 is used, steam reforming and reverse water-gas shift take place to increase the yield of CO and H2. This is in contrast to Ru/Al2O3, which catalyzes POM mostly by complete oxidation of CH4 to CO2 and H2O and subsequent reforming reactions. In the bimetallic catalyst, the main role of Ru is to reduce Re species, and the reduced Re species produces formate from CH4 and also accelerates the steam reforming reaction. The dual roles of Re increase the total catalytic performance. These results show that Re is a main player rather than a simple promoter in the catalytic reaction.
Intracerebral hemorrhage (ICH) is a common cerebrovascular disease, with a high rate of disability. In the literature on Chinese traditional medicine, there is increasing evidence that acupuncture ...can help hematoma absorption and improve neurological deficits after cerebral hemorrhage. Brain-derived neurotrophic factor (BDNF), one of the most studied neurotrophic factors, is involved in a variety of neurological functions and plays an important role in brain injury recovery. We investigated the effect of acupuncture intervention in the acute phase of ICH on the prognosis and serum BDNF levels of several patient groups.
To investigate the influence of acupuncture on the prognosis and brain-derived neurotrophic factor (BDNF) levels in patients in the acute phase of ICH.
From November 2021 to May 2022, 109 subjects were consecutively enrolled, including patients with ICH, who were randomized into the acupuncture group (AG) and sham acupuncture group (SAG), and a control group (CG). The CG received the same acupuncture intervention as the AG, and the SAG received sham acupuncture, with 14 interventions in each group. The level of consciousness of patients with ICH was assessed and serum BDNF levels were measured in all three groups before the intervention and at 3 weeks after onset, and the level of consciousness and outcomes were assessed at 12 weeks after onset.
After the intervention, the level of consciousness of the AG improved significantly (
< 0.05); the BDNF level of only the AG increased significantly (
< 0.05); the changes in Glasgow Coma Scale (GCS) score and BDNF level were significantly greater in the AG than in the SAG (
< 0.05), especially for locomotion (
< 0.05). At 12 weeks post-onset, the AG showed better outcomes and recovery of consciousness than the SAG (
< 0.05).
Although Ni–Ca-based dual functional materials (DFMs) have been examined for CO2 capture and reduction with H2 (CCR) for the synthesis of CH4, their performance has generally been investigated using ...single reactors in an oxygen-free environment. In addition, continuous CCR operations have scarcely been investigated. In this study, continuous CCR for the production of CH4 was investigated using a double reactor system over Al2O3-supported Ni–Ca DFMs in the presence of O2. We found that a high Ca loading (Ni(10)–Ca(30)/Al2O3, 10 wt% Ni, and 30 wt% CaO) was necessary for reaction efficiency under isothermal conditions at 450 °C. The optimized DFM exhibited an excellent performance (46% CO2 conversion, 45% CH4 yield, and 97% CH4 selectivity, respectively) and good stability over 24 h. The structure and CCR activity of Ni(10)–Ca(30)/Al2O3 were studied using X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectrometry (EDS), temperature-programmed desorption (TPD), and temperature-programmed surface reaction (TPSR) techniques.
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
The activity and stability of supported metal catalysts is significantly influenced by the interactions between the metal and the support, the so-called metal–support interactions (MSIs). Here, we ...present a systematic study that uses both experimental and computational approaches to investigate MSIs between Re and oxide supports. Re dispersed on SiO2, Al2O3, and MgO tends to be aggregated whereas Re dispersed on TiO2, V2O5, ZrO2, Nb2O5, and CeO2 exhibits a high degree of dispersion. Electronic properties such as the position of the conduction-band minimum (CBM) of the oxide support, a proxy for the electron affinity (EA), and the Fermi energy (E F) of the supported Re, a proxy for the work function (WF), were found to be of particular importance to govern the degrees of dispersion and aggregation of Re. Metal-oxide supports that have an EA that is larger than the WF of Re, such as TiO2, V2O5, and CeO2, can accept electrons from Re into their CB, inducing a strong MSI. This results in a large Re adsorption energy (E ads) that leads to a high degree of dispersion for the supported Re metal. Our work describing the electronic interactions that govern the degree of dispersion will enable the synthesis of active and durable catalysts via the identification of suitable combinations of metals and oxides.
The activity and stability of supported metal catalysts, which exhibit high efficiency and activity, are significantly influenced by the interactions between the metal and the support, that is, ...metal-support interactions (MSIs). Here, we report an investigation of the MSIs between supported rhenium (Re) and oxide supports such as TiO
2
, SiO
2
, Al
2
O
3
, MgO, V
2
O
5
, and ZrO
2
using experimental and computational approaches. The reducibility of the Re species was found to strongly depend on the oxide support. Experimental studies including temperature-programmed reduction by H
2
as well as Re L
3
- and L
1
-edge X-ray absorption near edge structure (XANES) analysis revealed that the valency of the Re species started to decrease upon H
2
reduction in the 200-400 °C range, except for Re on MgO, where the shift occurred at temperatures above 500 °C. The dependence of the Re L
3
- and L
1
-edge XANES spectra of the oxide-supported Re catalysts on the size of Re was also examined.
The dependence of the Re L
3
- and L
1
-edge XANES spectra on the Re size was investigated, which revealed that the L
3
-edge was more sensitive than the L
1
-edge to the size of the Re clusters.
