Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is...Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.展开更多
Pd/Ag/α-Al2O3 composite membranes were prepared by sequential electroless plating technique. The prepared membranes were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, energy disper...Pd/Ag/α-Al2O3 composite membranes were prepared by sequential electroless plating technique. The prepared membranes were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, energy dispersive spectroscopy, and inductively coupled plasma atomic emission spectroscopy techniques （ICP-AES）. Effects of annealing time, Ag content, and air treatment on the hydrogen permeation flux and morphology of the alloys were investigated. The results of the investigation showed that the prepared type of tube had a good potential as substrate for membrane preparation. In addition, a uniform defect-free alloy was prepared by annealing at 550 ℃ in H2 atmosphere. The permeation results showed an increase in H2 permeation flux by increasing the Ag content and the annealing time. In addition, the air treatment of the prepared membranes at 400 ℃ for 1 h changed the morphology of the alloy and substantially enhanced the hydrogen flux.展开更多
The electro-catalytic properties can be effectively optimized by designing bimetallic alloy nanoparticles with high-content less-active metal to enhance the competence of more-active noble metal. Herein, a one-pot hyd...The electro-catalytic properties can be effectively optimized by designing bimetallic alloy nanoparticles with high-content less-active metal to enhance the competence of more-active noble metal. Herein, a one-pot hydrothermal approach is demonstrated for the controllable synthesis of Ag-rich Ag_9Pd_1 alloy nanoactiniae with obviously enhanced electro-catalytic activity(2.23 mA cm^(-2) at 0.85 V) and stability for oxygen reduction reaction. In alkaline solution, the ORR onset potential and half-wave potential of the Ag_9Pd_1 alloy nanoactiniae can reach a value of 1.02 V and 0.89 V, respectively, which origin from strong ligand and ensemble effects between Pd element and Ag element. The nanocrystals are uniformly alloyed, displaying a Ag_9Pd_1 combination, as displayed by an assembly of X-ray diffraction(XRD) spectrum,energy dispersive X-ray(EDX) analysis, and cyclic voltammetry(CV). This concept of tuning bimetallic alloy nanocrystals with low concentrations of more precious metal may be a promising approach to be applicable to a wide range of alloy nanocrystals.展开更多
Doping foreign atom(s)in metal nanoclusters is an effective strategy to engineer the properties and functionalities of metal nanoclusters.However,until now,to dope Pd atom into Ag nanoclusters remains a huge challenge...Doping foreign atom(s)in metal nanoclusters is an effective strategy to engineer the properties and functionalities of metal nanoclusters.However,until now,to dope Pd atom into Ag nanoclusters remains a huge challenge.Here we develop a one-step rapid method to synthesize the Pd-doped Ag nanocluster with high yield.The prepared Pd1Ag28 nanocluster was characterized by mass spectroscopy,X-ray photoelectron spectroscopy,X-ray crystallography,fluorescence spectroscopy,ultraviolet-visible absorption spectroscopy and transient absorption spectroscopy.The nanocluster exhibits a perfect face-centered cubic(FCC)kernel structure with a tetrahedron-like shell.Of note,Pd1Ag28 nanocluster had an unexpectedly long excited-state lifetime of 3.3 microseconds,which is the longest excited-state lifetime for Ag-based nanoclusters S0 far.Meanwhile,the excellent near-infrared luminescence indicated the nanocluster has the potential in fluorescent bio-imaging.Besides,it was revealed that Pd1Ag28 nanocluster could be transformed into Au1Ag28 nanocluster via ion exchange reaction of AuPPhzCl with Pd1Ag28 nanocluster.This work provides an efficient synthetic protocol of alloy nanoclusters and wil contribute to study the effect of foreign atom on the properties of metal nanoclusters.展开更多
By virtue of the atom-and step-economy, utilization of simple arenes as a supplant of pre-prepared aryl metal species or aryl halides for the synthesis of arylated chiral molecules has attracted great attention from t...By virtue of the atom-and step-economy, utilization of simple arenes as a supplant of pre-prepared aryl metal species or aryl halides for the synthesis of arylated chiral molecules has attracted great attention from the synthetic community. While transition-metal-catalyzed enantioselective diarylation of tethered alkenes has been employed to prepare important chiral cyclic compounds, the direct use of simple arenes as aryl precursors is still underdeveloped, probably due to the difficulties in the effective control of the reactivity, site-selectivity and/or enantioselectivity. Herein we report an asymmetric Pd/Ag dual metal catalytic system for the non-directed, site-and enantioselective domino Heck/intermolecular C–H functionalization of arenes.Mechanistic studies showed that Pd and Ag act in cooperation in the catalysis and the chiral bisphosphine ligand plays a bifunctional role, i.e., assisting the silver species in the cleavage of the aryl C–H bond, while inducing the enantioselectivity on direct complexation with palladium. This method provides an efficient approach to the corresponding chiral oxindoles with good enantiomeric excesses from a broad scope of arenes, including fluoroarenes, heteroarenes and several complex products derived from medicines or natural products.展开更多
基金supported by Beijing Natural Science Foundation(No.8244060)China Postdoctoral Science Foundation(No.2023M730143)+3 种基金the National Natural Science Foundation of China(No.22425601)the National Key R&D Program of China(No.2023YFB3810801)Beijing Nova Program(No.20240484659)the R&D Program of Beijing Municipal Education Commission(No.KZ202210005011).
文摘Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.
文摘Pd/Ag/α-Al2O3 composite membranes were prepared by sequential electroless plating technique. The prepared membranes were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, energy dispersive spectroscopy, and inductively coupled plasma atomic emission spectroscopy techniques （ICP-AES）. Effects of annealing time, Ag content, and air treatment on the hydrogen permeation flux and morphology of the alloys were investigated. The results of the investigation showed that the prepared type of tube had a good potential as substrate for membrane preparation. In addition, a uniform defect-free alloy was prepared by annealing at 550 ℃ in H2 atmosphere. The permeation results showed an increase in H2 permeation flux by increasing the Ag content and the annealing time. In addition, the air treatment of the prepared membranes at 400 ℃ for 1 h changed the morphology of the alloy and substantially enhanced the hydrogen flux.
基金sponsored by the National Natural Science Foundation of China (21576139, 21503111)the Natural Science Foundation of Jiangsu Province (BK20171473)+1 种基金the National and Local Joint Engineering Research Center of Biomedical Functional Materials, Natural Science Foundation of Jiangsu Higher Education Institutions of China (16KJB150020)a project sponsored by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The electro-catalytic properties can be effectively optimized by designing bimetallic alloy nanoparticles with high-content less-active metal to enhance the competence of more-active noble metal. Herein, a one-pot hydrothermal approach is demonstrated for the controllable synthesis of Ag-rich Ag_9Pd_1 alloy nanoactiniae with obviously enhanced electro-catalytic activity(2.23 mA cm^(-2) at 0.85 V) and stability for oxygen reduction reaction. In alkaline solution, the ORR onset potential and half-wave potential of the Ag_9Pd_1 alloy nanoactiniae can reach a value of 1.02 V and 0.89 V, respectively, which origin from strong ligand and ensemble effects between Pd element and Ag element. The nanocrystals are uniformly alloyed, displaying a Ag_9Pd_1 combination, as displayed by an assembly of X-ray diffraction(XRD) spectrum,energy dispersive X-ray(EDX) analysis, and cyclic voltammetry(CV). This concept of tuning bimetallic alloy nanocrystals with low concentrations of more precious metal may be a promising approach to be applicable to a wide range of alloy nanocrystals.
基金We acknowledge the National Natural Science Foundation of China(No.21601178).
文摘Doping foreign atom(s)in metal nanoclusters is an effective strategy to engineer the properties and functionalities of metal nanoclusters.However,until now,to dope Pd atom into Ag nanoclusters remains a huge challenge.Here we develop a one-step rapid method to synthesize the Pd-doped Ag nanocluster with high yield.The prepared Pd1Ag28 nanocluster was characterized by mass spectroscopy,X-ray photoelectron spectroscopy,X-ray crystallography,fluorescence spectroscopy,ultraviolet-visible absorption spectroscopy and transient absorption spectroscopy.The nanocluster exhibits a perfect face-centered cubic(FCC)kernel structure with a tetrahedron-like shell.Of note,Pd1Ag28 nanocluster had an unexpectedly long excited-state lifetime of 3.3 microseconds,which is the longest excited-state lifetime for Ag-based nanoclusters S0 far.Meanwhile,the excellent near-infrared luminescence indicated the nanocluster has the potential in fluorescent bio-imaging.Besides,it was revealed that Pd1Ag28 nanocluster could be transformed into Au1Ag28 nanocluster via ion exchange reaction of AuPPhzCl with Pd1Ag28 nanocluster.This work provides an efficient synthetic protocol of alloy nanoclusters and wil contribute to study the effect of foreign atom on the properties of metal nanoclusters.
基金supported by the National Key R&D Program of China (2021YFA1500100)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB0610000)+2 种基金the National Natural Science Foundation of China (92256303, 22171278, 21821002)the Shanghai Science and Technology Committee (23ZR1482400)the Natural Science Foundation of Ningbo (2023J034)。
文摘By virtue of the atom-and step-economy, utilization of simple arenes as a supplant of pre-prepared aryl metal species or aryl halides for the synthesis of arylated chiral molecules has attracted great attention from the synthetic community. While transition-metal-catalyzed enantioselective diarylation of tethered alkenes has been employed to prepare important chiral cyclic compounds, the direct use of simple arenes as aryl precursors is still underdeveloped, probably due to the difficulties in the effective control of the reactivity, site-selectivity and/or enantioselectivity. Herein we report an asymmetric Pd/Ag dual metal catalytic system for the non-directed, site-and enantioselective domino Heck/intermolecular C–H functionalization of arenes.Mechanistic studies showed that Pd and Ag act in cooperation in the catalysis and the chiral bisphosphine ligand plays a bifunctional role, i.e., assisting the silver species in the cleavage of the aryl C–H bond, while inducing the enantioselectivity on direct complexation with palladium. This method provides an efficient approach to the corresponding chiral oxindoles with good enantiomeric excesses from a broad scope of arenes, including fluoroarenes, heteroarenes and several complex products derived from medicines or natural products.
