The gasification and combustion of activated fuels produced from fluidized beds are beneficial for achieving clean and efficient coal utilization.In this study,a high-calcium coal was used for the activation process,c...The gasification and combustion of activated fuels produced from fluidized beds are beneficial for achieving clean and efficient coal utilization.In this study,a high-calcium coal was used for the activation process,carried out in a high-temperature vertical fluidized bed.The carbon and ash characteristics of activated fuels were studied.The reactivity of activated fuels was characterized using Raman test,and scanning electron microscopy coupled with energy-dispersive spectrometry(SEM-EDS).Inorganic components were characterized using X-ray diffraction(XRD)and X-ray fluorescence spectrometry(XRF).With the increase in temperature and equivalence ratio(ER),the graphitization degree of activated fuels decreases,and a higher proportion of active sites leads to,a better activation effect.The activation effect is optimized at the equivalence ratio of 0.45.As the temperature rises,the calcium-containing minerals in the raw coal are gradually transformed into anorthite(CaAl_(2)SiO_(7)),and the anhydrite(CaSO_(4))reacts with the reducing gas(CO)to produce oldhamite(CaS);Fe_(2)O_(3),as a fluxing agent,is prone to melting with silica-aluminates at high temperature.As the particle size of activated fuel increased,the relative enrichment index(REI)of heavy metals decreased.展开更多
Monodispersed Pt colloids with a mean size of 2 nm were deposited uniformly on the {110} facets of a rod-shaped rutile TiO_(2),forming a well-defined Pt/TiO_(2) system.Oxidative treatment of this precursor at elevated...Monodispersed Pt colloids with a mean size of 2 nm were deposited uniformly on the {110} facets of a rod-shaped rutile TiO_(2),forming a well-defined Pt/TiO_(2) system.Oxidative treatment of this precursor at elevated temperatures re-dispersed the Pt particles into clusters and single-atoms.Air-calcination at 673 K partially oxidized the Pt particle surface,while calcination at 773 K yielded Pt Oxclusters of 1.6 nm in 7–8 atomic layers.Further calcination at 873 K formed a mixture of raft-like PtO_(x) clusters(1.6 nm,1–2 atomic layers) and cationic single-atoms.When tested for CO oxidation at 373 K,the Pt particles showed a higher activity than the Pt Oxclusters,whereas the cationic single-atoms were much less active.Subsequent H_(2)-reduction at 473 K converted the partially oxidized Pt particles into the metallic species,but they were encapsulated by TiO_(2)–xoverlayers because of the strong metal–support interactions,which decreased the activity dramatically.H_(2)-reduction of the PtO_(x) clusters at473 K enhanced the fraction of metallic Pt species without changing the size and geometry,and promoted the activity substantially.H_(2)-treatment of Pt single-atoms at 473 K increased the activity only moderately because most Pt species still kept at cationic species.These results straightforwardly differentiated the catalytic behavior of Pt particles,clusters and single-atoms at the same metal loading and over the same TiO_(2) support,and further demonstrated that the electronic structures of Pt entities played a decisive role in the catalytic oxidation,in addition to the specified sizes.展开更多
Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates,which are still unachievable for most of the closest-packed metals.Here,we report a facile chemical synthetic strategy for single-e...Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates,which are still unachievable for most of the closest-packed metals.Here,we report a facile chemical synthetic strategy for single-element amorphous palladium nanoparticles with a purity of 99.35 at.%±0.23 at.%from palladium–silicon liquid droplets.In-situ transmission electron microscopy directly detected the solidification of palladium and the separation of silicon.Further hydrogen absorption experiment showed that the amorphous palladium expanded little upon hydrogen uptake,exhibiting a great potential application for hydrogen separation.Our results provide insight into the formation of amorphous metal at nanoscale.展开更多
Recent advances in n-type conducting polymers are beginning to rival those of p-type materials.Notably,the n-type conducting polymer poly(benzodifurandione)(PBFDO)demonstrates a notable Seebeck coefficient along with ...Recent advances in n-type conducting polymers are beginning to rival those of p-type materials.Notably,the n-type conducting polymer poly(benzodifurandione)(PBFDO)demonstrates a notable Seebeck coefficient along with exceptionally high electrical conductivity,positioning it as a promising n-type thermoelectric material with substantial research potential.Despite its promise,the exploration of PBFDO’s thermoelectric properties and the development of related thermoelectric devices have been limited.In this study,we introduce a flexible thermoelectric device that utilizes a combination of the p-type polymer poly(3,4ethylenedioxythiophene):polystyrene sulfonate and the n-type polymer PBFDO,using a straightforward print-and-fold technique.This approach enabled the production of flexible devices with thermoelectric generators whose properties were assessed.The polymer films and the resultant devices demonstrated commendable performance stability even after being subjected to 1,000 bending cycles at a 90°angle.Our findings corroborate the potential of PBFDO as a viable material for flexible thermoelectric applications,a development that is eagerly anticipated in the field.展开更多
Oxygen evolution reactions(OER)are critical to electrochemical syn-thesis reactions,including hydrogen production and organic hydroge-nation.However,the high cost of existing OER catalysts(primarily Ir/Ru and its deri...Oxygen evolution reactions(OER)are critical to electrochemical syn-thesis reactions,including hydrogen production and organic hydroge-nation.However,the high cost of existing OER catalysts(primarily Ir/Ru and its derived oxides)limits their practical application for electro-chemical synthesis.To develop a low‐cost,high‐efficiency alternative,we need a deeper understanding of both the mechanisms that drive OER and the relationship between the catalyst's electronic structure and active sites.Here,we summarized recent developments of catalysts,especially focusing on the electronic structure modulation strategies and their subsequent activity enhancement.Most importantly,we pointed out the study directions for further work.展开更多
基金supported by CAS Project for Young Scientists in Basic Research(YSBR-028)the Youth Innovation Promotion Association CAS(2020150).
文摘The gasification and combustion of activated fuels produced from fluidized beds are beneficial for achieving clean and efficient coal utilization.In this study,a high-calcium coal was used for the activation process,carried out in a high-temperature vertical fluidized bed.The carbon and ash characteristics of activated fuels were studied.The reactivity of activated fuels was characterized using Raman test,and scanning electron microscopy coupled with energy-dispersive spectrometry(SEM-EDS).Inorganic components were characterized using X-ray diffraction(XRD)and X-ray fluorescence spectrometry(XRF).With the increase in temperature and equivalence ratio(ER),the graphitization degree of activated fuels decreases,and a higher proportion of active sites leads to,a better activation effect.The activation effect is optimized at the equivalence ratio of 0.45.As the temperature rises,the calcium-containing minerals in the raw coal are gradually transformed into anorthite(CaAl_(2)SiO_(7)),and the anhydrite(CaSO_(4))reacts with the reducing gas(CO)to produce oldhamite(CaS);Fe_(2)O_(3),as a fluxing agent,is prone to melting with silica-aluminates at high temperature.As the particle size of activated fuel increased,the relative enrichment index(REI)of heavy metals decreased.
基金supported by the National Natural Science Foundation of China (22002164)。
文摘Monodispersed Pt colloids with a mean size of 2 nm were deposited uniformly on the {110} facets of a rod-shaped rutile TiO_(2),forming a well-defined Pt/TiO_(2) system.Oxidative treatment of this precursor at elevated temperatures re-dispersed the Pt particles into clusters and single-atoms.Air-calcination at 673 K partially oxidized the Pt particle surface,while calcination at 773 K yielded Pt Oxclusters of 1.6 nm in 7–8 atomic layers.Further calcination at 873 K formed a mixture of raft-like PtO_(x) clusters(1.6 nm,1–2 atomic layers) and cationic single-atoms.When tested for CO oxidation at 373 K,the Pt particles showed a higher activity than the Pt Oxclusters,whereas the cationic single-atoms were much less active.Subsequent H_(2)-reduction at 473 K converted the partially oxidized Pt particles into the metallic species,but they were encapsulated by TiO_(2)–xoverlayers because of the strong metal–support interactions,which decreased the activity dramatically.H_(2)-reduction of the PtO_(x) clusters at473 K enhanced the fraction of metallic Pt species without changing the size and geometry,and promoted the activity substantially.H_(2)-treatment of Pt single-atoms at 473 K increased the activity only moderately because most Pt species still kept at cationic species.These results straightforwardly differentiated the catalytic behavior of Pt particles,clusters and single-atoms at the same metal loading and over the same TiO_(2) support,and further demonstrated that the electronic structures of Pt entities played a decisive role in the catalytic oxidation,in addition to the specified sizes.
基金supported by the National Natural Science Foundation of China(Nos.51602143,51702150,11874194,11774142,and 11874194)the Science and Technology Innovation Committee Foundation of Shenzhen(Nos.KQTD2016022619565991,JCYJ20200109141205978,and ZDSYS20141118160434515)+1 种基金the Natural Science Foundation of Guangdong Province(No.2015A030308001)the Leading Talents of Guangdong Province Program(No.00201517)。
文摘Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates,which are still unachievable for most of the closest-packed metals.Here,we report a facile chemical synthetic strategy for single-element amorphous palladium nanoparticles with a purity of 99.35 at.%±0.23 at.%from palladium–silicon liquid droplets.In-situ transmission electron microscopy directly detected the solidification of palladium and the separation of silicon.Further hydrogen absorption experiment showed that the amorphous palladium expanded little upon hydrogen uptake,exhibiting a great potential application for hydrogen separation.Our results provide insight into the formation of amorphous metal at nanoscale.
基金supported by National Natural Science Foundation of China(no.52003202)Science Foundation for High-Level Talents of Wuyi University(2020AL004).
文摘Recent advances in n-type conducting polymers are beginning to rival those of p-type materials.Notably,the n-type conducting polymer poly(benzodifurandione)(PBFDO)demonstrates a notable Seebeck coefficient along with exceptionally high electrical conductivity,positioning it as a promising n-type thermoelectric material with substantial research potential.Despite its promise,the exploration of PBFDO’s thermoelectric properties and the development of related thermoelectric devices have been limited.In this study,we introduce a flexible thermoelectric device that utilizes a combination of the p-type polymer poly(3,4ethylenedioxythiophene):polystyrene sulfonate and the n-type polymer PBFDO,using a straightforward print-and-fold technique.This approach enabled the production of flexible devices with thermoelectric generators whose properties were assessed.The polymer films and the resultant devices demonstrated commendable performance stability even after being subjected to 1,000 bending cycles at a 90°angle.Our findings corroborate the potential of PBFDO as a viable material for flexible thermoelectric applications,a development that is eagerly anticipated in the field.
基金Shenzhen fundamental research funding,Grant/Award Numbers:JCYJ20200109141216566,JCYJ20210324115809026,JCYJ20220818100212027Guangdong scientific program,Grant/Award Number:2019QN01L057+2 种基金National Key Research and Development Project,Grant/Award Numbers:2022YFA1203400,2022YFA1503900Southern University of Science and TechnologyDevelopment and Reform Commission of Shenzhen Municipality。
文摘Oxygen evolution reactions(OER)are critical to electrochemical syn-thesis reactions,including hydrogen production and organic hydroge-nation.However,the high cost of existing OER catalysts(primarily Ir/Ru and its derived oxides)limits their practical application for electro-chemical synthesis.To develop a low‐cost,high‐efficiency alternative,we need a deeper understanding of both the mechanisms that drive OER and the relationship between the catalyst's electronic structure and active sites.Here,we summarized recent developments of catalysts,especially focusing on the electronic structure modulation strategies and their subsequent activity enhancement.Most importantly,we pointed out the study directions for further work.
