Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis so...Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis software was used for quantitative analysis.The variation of mechanical properties before and after overtemperature treatment was tested.Results show that the Ti_(2)AlNb alloy consists of B2 phase and lamellar O phase before and after overtemperature treatment.After overtemperature treatment,partial B2 phase is transformed into the O phase,and the lamellar structure of O phase suffers discontinuous coarsening and spherolization.The coarsening degree is increased with the increase in temperature and prolongation of treatment time,and O phase content is also gradually increased.The microhardness and tensile properties of Ti_(2)AlNb alloys at room and high temperatures are decreased with the increase in temperature and prolongation of treatment time,and the high-temperature tensile strength exhibits relatively larger decrement.An obvious linear relationship exists between microhardness and O phase content.Both the microhardness and the O phase content are important parameters to evaluate the overtemperature service damage degree of precision-cast Ti_(2)AlNb alloy.展开更多
This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0...This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.1)Mo_(0.05)O_(3-δ)(B S CNM_(0.05)),Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.05)Mo_(0.1)O_(3-δ)(BSCNM_(0.1)),and Ba_(0.6)Sr_(0.4)Co_(0.85)Mo_(0.15)O_(3-δ)(BSCM)—with Mo doping contents of 5mol%,10mol%,and15mol%,respectively,were successfully prepared using the sol-gel method.The effects of Mo doping on the crystal structure,conductivity,thermal expansion coefficient,oxygen reduction reaction(ORR)activity,and electrochemical performance were systematically evaluated using X-ray diffraction analysis,thermally induced characterization,electrochemical impedance spectroscopy,and single-cell performance tests.The results revealed that Mo doping could improve the conductivity of the materials,suppress their thermal expansion effects,and significantly improve the electrochemical performance.Surface chemical state analysis using X-ray photoelectron spectroscopy revealed that 5mol%Mo doping could facilitate a high adsorbed oxygen concentration leading to enhanced ORR activity in the materials.Density functional theory calculations confirmed that Mo doping promoted the ORR activity in the materials.At an operating temperature of 600℃,the BSCNM_(0.05)cathode material exhibited significantly enhanced electrochemical impedance characteristics,with a reduced area specific resistance of 0.048Ω·cm~2,which was lower than that of the undoped BSCN matrix material by 32.39%.At the same operating temperature,an anode-supported single cell using a BSCNM_(0.05)cathode achieved a peak power density of 1477 mW·cm^(-2),which was 30.71%,56.30%,and 171.50%higher than those of BSCN,BSCNM_(0.1),and B SCM,respectively.The improved ORR activity and electrochemical performance of BSCNM_(0.05)indicate that it can be used as a cathode material in low-temperature solid oxide fuel cells.展开更多
To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells(ITSOFCs),10mol%Ta5+doped in the B site of strontium ferrite perovskite oxide(SrTa_(0.1)Fe_(0.9)O_...To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells(ITSOFCs),10mol%Ta5+doped in the B site of strontium ferrite perovskite oxide(SrTa_(0.1)Fe_(0.9)O_(3-δ),STF)is investigated and optimized.The effects of Ta^(5+)doping on structure,transition metal reduction,oxygen nonstoichiometry,thermal expansion,and electrical performance are evaluated systematically.Via 10mol%Ta^(5+)doping,the thermal expansion coefficient(TEC)decreased from 34.1×10^(-6)(SrFeO_(3-δ))to 14.6×10^(-6) K^(-1)(STF),which is near the TEC of electrolyte(13.3×10^(-6) K^(-1) for Sm_(0.2)Ce_(0.8)O_(1.9),SDC),indicates excellent thermomechanical compatibility.At 550-750℃,STF shows superior oxygen vacancy concentrations(0.262 to 0.331),which is critical in the oxygen-reduction reaction(ORR).Oxygen temperature-programmed desorption(O_(2)-TPD)indicated the thermal reduction onset temperature of iron ion is around 420℃,which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves.At 600℃,the STF electrode shows area-specific resistance(ASR)of 0.152Ω·cm^(2) and peak power density(PPD)of 749 mW·cm^(-2).ORR activity of STF was further improved by introducing 30wt%Sm_(0.2)Ce_(0.8)O_(1.9)(SDC)powder,STF+SDC composite cathode achieving outstanding ASR value of 0.115Ω·cm2 at 600℃,even comparable with benchmark cobalt-containing cathode,Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)(BSCF).Distribution of relaxation time(DRT)analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode.At 650℃,STF+SDC composite cathode achieving an outstanding PPD of 1117 mW·cm^(-2).The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.展开更多
Dear Editor,The ongoing threat of tick-borne diseases,especially the increasing rate of new infections caused by tick-borne viruses has drawn wide attention in recent years(Madison-Antenucci et al.,2020;Yang et al.,20...Dear Editor,The ongoing threat of tick-borne diseases,especially the increasing rate of new infections caused by tick-borne viruses has drawn wide attention in recent years(Madison-Antenucci et al.,2020;Yang et al.,2023).Therefore,there is a need to strengthen the surveillance of a wide range of viruses carried by ticks to prevent outbreaks of tick-borne diseases.展开更多
A series of thermoplastic polyimide resins with a low coefficient of thermal expansion(CTE)were prepared by blending a rigid resin system 3,3’,4,4’-biphenyltetracarboxylic dianhydride(BPDA)/p-phenylenediamine(PDA)wi...A series of thermoplastic polyimide resins with a low coefficient of thermal expansion(CTE)were prepared by blending a rigid resin system 3,3’,4,4’-biphenyltetracarboxylic dianhydride(BPDA)/p-phenylenediamine(PDA)with a flexible resin system 4,4’-[isopropylidenebis(pphenyleneoxy)]diphthalic anhydride(BPADA)/PDA.The effects of the blending ratio on the macromolecular coil size,free volume,and CTE of the mixed system were studied.The mixing is carried out in the prepolymer poly(amide acid)(PAA)stage,which makes the two systems more compatible and is conducive to the formation of a semi-interpenetrating network structure between the rigid molecular chains and flexible molecular chains.The flexible structure of the BPADA/PDA system is used to ensure the melt processing performance.The rigid characteristics of the BPDA/PDA system can inhibit the movement of molecular chains and reduce the free volume fraction,thereby reducing the CTE value.When the rigid system content reaches 30%,the CTE can be reduced to 38 ppm/K.This method provides a new approach for studying low CTE thermoplastic polyimide resins.展开更多
Electrochemical carbon dioxide reduction reaction(CO_(2)RR)into high-value added chemicals and fuels has aroused wide attention,but suffers from high overpotential and poor selectivity.Herein,nitrogen-doped carbon sup...Electrochemical carbon dioxide reduction reaction(CO_(2)RR)into high-value added chemicals and fuels has aroused wide attention,but suffers from high overpotential and poor selectivity.Herein,nitrogen-doped carbon supported Fe and Mn heteronuclear single atom catalysts with different Fe and Mn inter-site distance were fabricated via a templating isolation approach and tested for CO_(2)RR to CO in an aqueous solution.The catalyst with atomically dispersed Fe and Mn sites in close proximity exhibited the highest CO_(2)RR performance,with a CO Faradaic efficiency of 96%at a low overpotential of 320 mV,and a Tafel slope of only 62 mV·dec^(−1),comparable to state-of-the-art gold catalysts.Experimental analysis combined with theory highlighted that single Mn atom at the neighboring site of Fe enhanced the electronic localization of Fe center,which facilitated the generation of key^(*)COOH intermediate as well as CO^(*) desorption on Fe,leading to superior CO_(2)RR performance at low overpotentials.This work offers atomic-level insights into the correlation between the inter-site distance of atomic sites and CO_(2)RR performance,and paves a new avenue for precise control of single-atom sites on carbon surface for highly active and selective electrocatalysts.展开更多
Rehabilitation assessment plays a vital role in the recovery process of post-stroke patients.Currently,many studies have focused on the implementation of automated assessment scales.However,the impact of stroke on the...Rehabilitation assessment plays a vital role in the recovery process of post-stroke patients.Currently,many studies have focused on the implementation of automated assessment scales.However,the impact of stroke on the synergistic pattern between different human joints is not well understood.In this study,we developed an attention-coupled weighting based quantitative analysis model to identify the pathological alteration in the conjoint response structure between stroke patients and healthy participants,thus providing more intrinsic suggestions for the post-stroke rehabilitation training.In collaboration with the China Rehabilitation Research Center and the Macao University of Science and Technology,we recruited 15 post-stroke patients and 15 healthy participants to complete several actions selected from the Fugl-Meyer assessment(FMA)scale,which is a commonly used post-stroke rehabilitation assessment scale in clinical practice.Our study proposed an attentional coupling weight(ACW)extraction method.By filtering the weights in the attentional coupling network using a priori matrix,we can analyse the effect of stroke on the alteration of synergistic structures and the coordination patterns of the upper and lower extremities.Moreover,we used a commonly accepted synergy analysis method,the nonnegative matrix decomposition(NMF)method,for comparison and validation.The experimental results demonstrated the effectiveness of our method in quantifying the synergistic structure pattern alterations in post-stroke patients,which provides a new targeted option for the rehabilitation process.展开更多
Peripheral nerve injury presents a significant clinical challenge due to the limited regenerative capacity of the injured nerves,often resulting in permanent functional deficits.A key obstacle to effective nerve regen...Peripheral nerve injury presents a significant clinical challenge due to the limited regenerative capacity of the injured nerves,often resulting in permanent functional deficits.A key obstacle to effective nerve regeneration is the inability to modulate the inflammatory response,guide axonal elongation,and promote myelination.To address these challenges,we developed a multi-channel nerve guidance conduit(NGC)that integrated immune-modulating drug with gradient cues to enhance peripheral nerve regeneration.The inner tubes of the conduit were composed of degradable electrospun gelatin methacryloyl/collagen(GelMA/COL)fibers loaded with 1400W,an inducible nitric oxide synthase(iNOS)inhibitor.The outer tube consisted of electrospun polycaprolactone(PCL)fibers decorated with a density gradient of collagen particles encapsulating acidic fibroblast growth factor(aFGF).The release of 1400W enhanced macrophage activity and promoted their polarization from the pro-inflammatory M1 phenotype to the reparative M2 phenotype,thereby creating a pro-regenerative microenvironment conducive to nerve repair.The incorporation of gradient cues guided and promoted Schwann cell migration and neurite extension in vitro.In a rat sciatic nerve injury model,the conduit significantly improved nerve regeneration by sequentially modulating the inflammatory response and guiding axonal elongation,providing both spatial support and biological activity.Furthermore,the conduit promoted organized nerve fiber alignment,enhanced myelination,and achieved functional recovery outcomes that closely resembled those of the autograft.These findings suggest that the integration of immune-regulatory drug release,gradient cues,and a multi-channel structure presents a promising strategy for enhancing peripheral nerve repair.展开更多
Protonic ceramic fuel cells(PCFCs)are more suitable for operation at low temperatures due to their smaller activation energy(Ea).Unfortunately,the utilization of PCFC technology at reduced temperatures is limited by t...Protonic ceramic fuel cells(PCFCs)are more suitable for operation at low temperatures due to their smaller activation energy(Ea).Unfortunately,the utilization of PCFC technology at reduced temperatures is limited by the lack of durable and high-activity air electrodes.A lot number of cobalt-based oxides have been developed as air electrodes for PCFCs,due to their high oxygen reduction reaction(ORR)activity.However,cobalt-based oxides usually have more significant thermal expansion coefficients(TECs)and poor thermomechanical compatibility with electrolytes.These characteristics can lead to cell delamination and degradation.Herein,we rationally design a novel cobalt-containing composite cathode material with the nominal composition of Sr_(4)Fe_(4)Co_(2)O_(13)+δ(SFC).SFC is composed of tetragonal perovskite phase(Sr_(8)Fe_(8)O_(23)+δ,I4/mmm,81 wt.%)and spinel phase(Co_(3)O_(4),Fd3m,19 wt.%).The SFC composite cathode displays an ultra-high oxygen ionic conductivity(0.053 S·cm^(-1)at 550℃),superior CO_(2)tolerance,and suitable TEC value(17.01×10^(-6)K^(-1)).SFC has both the O_(2)^(-)/e^(-)conduction function,and the triple conducting(H^(+)/O_(2)^(-)/e^(-))capability was achieved by introducing the protonic conduction phase(BaZr_(0.2)Ce_(0.7)Y_(0.1)O_(3-δ),BZCY)to form SFC+BZCY(70 wt.%:30 wt.%).The SFC+BZCY composite electrode exhibits superior ORR activity at a reduced temperature with extremely low area-specific resistance(ASR,0.677Ω·cm^(2)at 550℃),profound peak power density(PPD,535 mW·cm^(-2)and 1.065 V at 550℃),extraordinarily long-term durability(>500 h for symmetrical cell and 350 h for single cell).Moreover,the composite has an ultra-low TEC value(15.96×10^(-6)K^(-1)).This study proves that SFC+BZCY with triple conducting capacity is an excellent cathode for low-temperature PCFCs.展开更多
The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanoca...The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8(ZIF-8)-based colloid particles(CPs)with an amorphous ZIF-8 skin.This encapsulation structure achieves an ultra-high loading rate(LR)of 90%(i.e.,9 mg doxorubicin(DOX)per 1 mg ZIF-8)for DOX and the protection of DOX from leaking.Notably,to deliver unit-dose drug,this ultra-high LR of 90%significantly reduces the usage of ZIF-8 to 1.2%(2 orders of magnitude)compared to that of DOX@ZIF-8 with a 10%LR,in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored.Safety,drug delivery efficacy,scale-up ability,and universality of this encapsulation structure have been further verified.Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.展开更多
As one of the main tumor-infiltrating immune cell types, tumor-associated macrophages (TAMs) determine the efficacy of immunotherapy. However, limited knowledge about their phenotypically and functionally heterogeneou...As one of the main tumor-infiltrating immune cell types, tumor-associated macrophages (TAMs) determine the efficacy of immunotherapy. However, limited knowledge about their phenotypically and functionally heterogeneous nature restricts their application in tumor immunotherapy. In this study, we identified a subpopulation of CD146+ TAMs that exerted antitumor activity in both human samples and animal models. CD146 expression in TAMs was negatively controlled by STAT3 signaling. Reducing this population of TAMs promoted tumor development by facilitating myeloid-derived suppressor cell recruitment via activation of JNK signaling. Interestingly, CD146 was involved in the NLRP3 inflammasome-mediated activation of macrophages in the tumor microenvironment, partially by inhibiting transmembrane protein 176B (TMEM176B), an immunoregulatory cation channel. Treatment with a TMEM176B inhibitor enhanced the antitumor activity of CD146+ TAMs. These data reveal a crucial antitumor role of CD146+ TAMs and highlight the promising immunotherapeutic approach of inhibiting CD146 and TMEM176B.展开更多
To enhance the performance and widespread use of solid oxide fuel cells(SOFCs),addressing the low-temperature(<650℃)electrochemical performance and operational stability issues of cathode materials is crucial.Here...To enhance the performance and widespread use of solid oxide fuel cells(SOFCs),addressing the low-temperature(<650℃)electrochemical performance and operational stability issues of cathode materials is crucial.Here,we propose an innovative approach to enhance oxygen ion mobility and electrochemical performance of perovskite oxide by substituting some oxygen sites with chlorine anions.The designed SrTa_(0.1)Fe_(0.9)O_(3-δ-x)Clx(x=0.05 and 0.10)exhibits improved performance compared to SrTa_(0.1)Fe_(0.9)O_(3-δ)(STF).SrTa_(0.1)Fe_(0.9)O_(2.95-δ)Cl_(0.05)(STFCl0.05)shows the lowest area-specific resistance(ASR)value on Sm0.2Ce0.8O1.9(SDC)electrolyte.At 600℃,STFCl0.05 achieves an ASR value of 0.084Ω·cm^(2),and a single cell with STFCl0.05 reaches a higher peak power density(PPD)value(1143 mW·cm^(-2))than that with STF(672 mW·cm^(-2)).Additionally,besides exhibiting excellent oxygen reduction reaction(ORR)activity at lower temperatures,the STFCl0.05 cathode demonstrates good CO_(2)tolerance and operational stability.Symmetrical cell operation lasts for 150 h,and single cell operation endures for 720 h without significant performance decline.The chlorine doping approach effectively enhances ORR activity and stability,making STFCl0.05 a promising cathode material for low-temperature SOFCs.展开更多
There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calc...There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calculations,the potential ofγ-graphyne(GY)as substrate for metals in the 4th and 5th periods under single-atom and dual-atoms concentration modes has been systematically investigated.It was found that single-atom Co,Ir,Rh,and Ru could effectively oxidate CO molecules,especially for single Rh.Furthermore,proper atoms concentration could boost the CO oxidation activity by supplying more reaction centers,such as Rh^(2)/GY.It was determined that two Rh atoms in Rh^(2)/GY act different roles in the catalytic reaction:one structural and another functional.Screening tests suggest that substituting the structural Rh atom in the center of acetylenic ring by Co or Cu atom is a possible way to maintain the reaction performance while reducing the noble metal cost.This systemic investigation will help in understanding the fundamental reaction mechanisms on GY-based substrates.We emphasize that properly exposed frontier orbital of functional metal atom is crucial in adsorption configuration as well as entire catalytic performance.This study constructs a workflow and provides valuable information for rational design of CO oxidation catalysts.展开更多
Plastic products widespread in natural water can be broken into smaller-sized microplastics(MPs,<5 mm)under light irradiation,thermal degradation and biodegradation,posing a serious threat to aquatic ecosystems and...Plastic products widespread in natural water can be broken into smaller-sized microplastics(MPs,<5 mm)under light irradiation,thermal degradation and biodegradation,posing a serious threat to aquatic ecosystems and human health.This perspective concludes that MPs can generate reactive oxygen species(ROS)through initiation,propagation and termination steps,which can attack the polymer resulting in the photoaging and breakdown of C–C and C–H bonds under ultraviolet(UV)irradiation.Free radical generation and weathering degree of MPs depend on their physicochemical properties and environmental conditions.In general,UV irradiation and co-existed MPs can significantly accelerate MP photoaging.With plentiful chromophores carbonyl,carboxyl and benzene rings,Dissolved organic matter(DOM)mainly absorbs photons(300–500 nm)and generates hydrated electrons,^(3)DOM^(*) and ROS,which may affect MP photoaging.However,whether DOM may transfer the electron and energy to MPs under UV irradiation,affect ROS generation of MPs and their photoaging pathway are inadequately studied.More studies are needed to elucidate MP photoaging pathways and mechanisms,consider the influence of stabilization capacity,photosensitization and photoionization of DOM as well as their competitive light absorption with MPs,which provides valuable insights into the environmental behavior and ecological risk of MPs in natural water.展开更多
The revelation of thermal energy exchange mechanism of human body is challenging yet worthwhile,because it can clearly explain the changes in human symptoms and health status.Understanding,the heat transfer of the ski...The revelation of thermal energy exchange mechanism of human body is challenging yet worthwhile,because it can clearly explain the changes in human symptoms and health status.Understanding,the heat transfer of the skin is significant because the skin is the foremost organ for the energy exchange between the human body and the environment.In order to diagnose the physiological conditions of human skin without causing any damage,it is necessary to use a non-invasive measurement technique by means of a conformal flexible sensor.The harmonic method can minimize the thermal-induced injury to the skin due to its low heat generating properties.A novel type of computational theory assessing skin thermal conductivity,blood perfusion rate of capillaries in the dermis,and superficial subcutaneous tissues was formed by combining the multi-medium thermal diffusion model and the bio-thermal model(Pennes equation).The skins of the hand back of six healthy subjects were measured.It was found that the results revealed no consistent changes in thermal conductivity were observed across genders and ages.The measured blood perfusion rates were within the range of human capillary flow.It was found that female subjects had a higher perfusion rate range(0.0058-0.0061 s^(-1))than male subjects(0.0032-0.0049 s^(-1)),which is consistent with invasive medical studies about the gender difference in blood flow rates and stimulated effects in relaxation situations.展开更多
Symmetric solid oxide fuel cells(SSOFCs)have gained significant attention owing to their cost-effective fabrication,superior thermomechanical compatibility,and enhanced long-term stability.Ammonia(NH_(3)),an excellent...Symmetric solid oxide fuel cells(SSOFCs)have gained significant attention owing to their cost-effective fabrication,superior thermomechanical compatibility,and enhanced long-term stability.Ammonia(NH_(3)),an excellent hydrogen carrier,is a promising clean energy source with high energy density,easy transportation and storage.Notably,NH_(3) contained only nitrogen and hydrogen,making it carbon-free.In this study,we synthesize the highly active symmetric electrode material Pr_(0.32)Sr_(0.48)Fe_(0.75)Ni_(0.2)Ru_(0.05)O_(3-δ)(PSFNRu)by replacing partial Fe in Pr_(0.32)Sr_(0.48)Fe_(0.8)Ni_(0.2)O_(3-δ)(PSFN)with 5 mol%Ru.PSFNRu possesses a sufficient quantity of oxygen vacancies,with the capacity to in-situ exsolved alloy nanoparticles(ANPs)in a reducing atmosphere.This nanocomposite is found to promote electrochemical reactions.For example,at 800℃,the SSOFC employing the PSFNRu electrode achieves a peak power density(PPD)of 736 mW·cm^(-2) when using hydrogen(H_(2))as the fuel.Under NH_(3) conditions,the cell delivers a PPD of 547 mW·cm^(-2),significantly surpassing the 462 mW·cm^(-2) recorded for a comparable cell employing the PSFN electrode.The enhanced cell performance is mainly ascribed to Ru doping,which boosts the ORR activity and facilitates the in-situ exsolution of ANPs at the anode,increasing active sites and accelerating NH_(3) decomposition.In addition,remarkable operational stability of the single cell(172 h under NH_(3) fuel at 700℃)is also demonstrated.These encouraging experimental results highlight the superiority of PSFNRu as the bi-functional electrodes for direct ammonia symmetric solid oxide fuel cells(DA-SSOFCs),and providing a potential and reliable pathway towards accelerating the development of DA-SSOFCs.展开更多
High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance,but still challenging.Herein,a new strategy,consisting of using diatomic synergistic modulation(DSM)...High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance,but still challenging.Herein,a new strategy,consisting of using diatomic synergistic modulation(DSM)to effectively control the separation of photo-generated carriers for an enhanced production of phenol is reported.The atomic level dispersion of Fe and Cr respectively decorated on Al based MIL-53-NH_(2)photocatalyst(Fe1/Cr:MIL-53-NH_(2))is designed,in which Cr single atoms are substituted for Al3+while Fe single atoms are coordinated by N.Notably,the Fe1/Cr:MIL-53-NH_(2)significantly boosts the photooxidation of benzene to phenol under visible light irradiation,which is much higher than those of MIL-53-NH_(2),Cr:MIL-53-NH_(2),Fe1/MIL-53-NH_(2),and Fe nanoparticles/Cr:MIL-53-NH_(2)catalysts.Theoretical and experimental results reveal that the Cr single atoms and Fe single atoms can act as electron acceptor and electron donor,respectively,during photocatalytic reaction,exhibiting a synergistic effect on the separation of the photo-generated carriers and thereby causing great enhancement on the benzene oxidation.This strategy provides new insights for rational design of advanced photocatalysts at the atomic level.展开更多
文摘Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis software was used for quantitative analysis.The variation of mechanical properties before and after overtemperature treatment was tested.Results show that the Ti_(2)AlNb alloy consists of B2 phase and lamellar O phase before and after overtemperature treatment.After overtemperature treatment,partial B2 phase is transformed into the O phase,and the lamellar structure of O phase suffers discontinuous coarsening and spherolization.The coarsening degree is increased with the increase in temperature and prolongation of treatment time,and O phase content is also gradually increased.The microhardness and tensile properties of Ti_(2)AlNb alloys at room and high temperatures are decreased with the increase in temperature and prolongation of treatment time,and the high-temperature tensile strength exhibits relatively larger decrement.An obvious linear relationship exists between microhardness and O phase content.Both the microhardness and the O phase content are important parameters to evaluate the overtemperature service damage degree of precision-cast Ti_(2)AlNb alloy.
基金financially supported by the National Natural Science Foundation of China(No.22309067)the Open Project Program of the State Key Laboratory of Materials-Oriented Chemical Engineering,China(No.KL21-05)the Marine Equipment and Technology Institute,Jiangsu University of Science and Technology,China(No.XTCX202404)。
文摘This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.1)Mo_(0.05)O_(3-δ)(B S CNM_(0.05)),Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.05)Mo_(0.1)O_(3-δ)(BSCNM_(0.1)),and Ba_(0.6)Sr_(0.4)Co_(0.85)Mo_(0.15)O_(3-δ)(BSCM)—with Mo doping contents of 5mol%,10mol%,and15mol%,respectively,were successfully prepared using the sol-gel method.The effects of Mo doping on the crystal structure,conductivity,thermal expansion coefficient,oxygen reduction reaction(ORR)activity,and electrochemical performance were systematically evaluated using X-ray diffraction analysis,thermally induced characterization,electrochemical impedance spectroscopy,and single-cell performance tests.The results revealed that Mo doping could improve the conductivity of the materials,suppress their thermal expansion effects,and significantly improve the electrochemical performance.Surface chemical state analysis using X-ray photoelectron spectroscopy revealed that 5mol%Mo doping could facilitate a high adsorbed oxygen concentration leading to enhanced ORR activity in the materials.Density functional theory calculations confirmed that Mo doping promoted the ORR activity in the materials.At an operating temperature of 600℃,the BSCNM_(0.05)cathode material exhibited significantly enhanced electrochemical impedance characteristics,with a reduced area specific resistance of 0.048Ω·cm~2,which was lower than that of the undoped BSCN matrix material by 32.39%.At the same operating temperature,an anode-supported single cell using a BSCNM_(0.05)cathode achieved a peak power density of 1477 mW·cm^(-2),which was 30.71%,56.30%,and 171.50%higher than those of BSCN,BSCNM_(0.1),and B SCM,respectively.The improved ORR activity and electrochemical performance of BSCNM_(0.05)indicate that it can be used as a cathode material in low-temperature solid oxide fuel cells.
基金financially supported by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.2018ND133J)the National Natural Science Foundation of China(Nos.22309067 and 22101150)the Natural Science Foundation of Jiangsu Province,China(No.BK20190965).
文摘To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells(ITSOFCs),10mol%Ta5+doped in the B site of strontium ferrite perovskite oxide(SrTa_(0.1)Fe_(0.9)O_(3-δ),STF)is investigated and optimized.The effects of Ta^(5+)doping on structure,transition metal reduction,oxygen nonstoichiometry,thermal expansion,and electrical performance are evaluated systematically.Via 10mol%Ta^(5+)doping,the thermal expansion coefficient(TEC)decreased from 34.1×10^(-6)(SrFeO_(3-δ))to 14.6×10^(-6) K^(-1)(STF),which is near the TEC of electrolyte(13.3×10^(-6) K^(-1) for Sm_(0.2)Ce_(0.8)O_(1.9),SDC),indicates excellent thermomechanical compatibility.At 550-750℃,STF shows superior oxygen vacancy concentrations(0.262 to 0.331),which is critical in the oxygen-reduction reaction(ORR).Oxygen temperature-programmed desorption(O_(2)-TPD)indicated the thermal reduction onset temperature of iron ion is around 420℃,which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves.At 600℃,the STF electrode shows area-specific resistance(ASR)of 0.152Ω·cm^(2) and peak power density(PPD)of 749 mW·cm^(-2).ORR activity of STF was further improved by introducing 30wt%Sm_(0.2)Ce_(0.8)O_(1.9)(SDC)powder,STF+SDC composite cathode achieving outstanding ASR value of 0.115Ω·cm2 at 600℃,even comparable with benchmark cobalt-containing cathode,Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)(BSCF).Distribution of relaxation time(DRT)analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode.At 650℃,STF+SDC composite cathode achieving an outstanding PPD of 1117 mW·cm^(-2).The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.
文摘Dear Editor,The ongoing threat of tick-borne diseases,especially the increasing rate of new infections caused by tick-borne viruses has drawn wide attention in recent years(Madison-Antenucci et al.,2020;Yang et al.,2023).Therefore,there is a need to strengthen the surveillance of a wide range of viruses carried by ticks to prevent outbreaks of tick-borne diseases.
基金financially supported by the National Natural Science Foundation of China(No.51773007)the Fundamental Research Funds for the Central Universities(No.XK1802-2)。
文摘A series of thermoplastic polyimide resins with a low coefficient of thermal expansion(CTE)were prepared by blending a rigid resin system 3,3’,4,4’-biphenyltetracarboxylic dianhydride(BPDA)/p-phenylenediamine(PDA)with a flexible resin system 4,4’-[isopropylidenebis(pphenyleneoxy)]diphthalic anhydride(BPADA)/PDA.The effects of the blending ratio on the macromolecular coil size,free volume,and CTE of the mixed system were studied.The mixing is carried out in the prepolymer poly(amide acid)(PAA)stage,which makes the two systems more compatible and is conducive to the formation of a semi-interpenetrating network structure between the rigid molecular chains and flexible molecular chains.The flexible structure of the BPADA/PDA system is used to ensure the melt processing performance.The rigid characteristics of the BPDA/PDA system can inhibit the movement of molecular chains and reduce the free volume fraction,thereby reducing the CTE value.When the rigid system content reaches 30%,the CTE can be reduced to 38 ppm/K.This method provides a new approach for studying low CTE thermoplastic polyimide resins.
基金supported by National Natural Science Foundation of China(Nos.22478419,22102080,and 221011150)Key Project of National Natural Science Foundation of China(No.U22B20149)+2 种基金Science Foundation of China University of Petroleum(Beijing)(No.ZX20230067)The authors acknowledge the Dutch Organization for Scientific Research(NWO)for access to the Dutch national e-infrastructure(Nos.EINF-4693 and EINF-6899)The authors thank the BL14W1 station in Shanghai Synchrotron Radiation Facility(SSRF)and the 1W1B station in Beijing Synchrotron Radiation Facility(BSRF)for XAFS test.
文摘Electrochemical carbon dioxide reduction reaction(CO_(2)RR)into high-value added chemicals and fuels has aroused wide attention,but suffers from high overpotential and poor selectivity.Herein,nitrogen-doped carbon supported Fe and Mn heteronuclear single atom catalysts with different Fe and Mn inter-site distance were fabricated via a templating isolation approach and tested for CO_(2)RR to CO in an aqueous solution.The catalyst with atomically dispersed Fe and Mn sites in close proximity exhibited the highest CO_(2)RR performance,with a CO Faradaic efficiency of 96%at a low overpotential of 320 mV,and a Tafel slope of only 62 mV·dec^(−1),comparable to state-of-the-art gold catalysts.Experimental analysis combined with theory highlighted that single Mn atom at the neighboring site of Fe enhanced the electronic localization of Fe center,which facilitated the generation of key^(*)COOH intermediate as well as CO^(*) desorption on Fe,leading to superior CO_(2)RR performance at low overpotentials.This work offers atomic-level insights into the correlation between the inter-site distance of atomic sites and CO_(2)RR performance,and paves a new avenue for precise control of single-atom sites on carbon surface for highly active and selective electrocatalysts.
基金supported in part by the National Key Research and Development Program of China(No.2022YFC3601200)in part by the National Natural Science Foundation of China(Nos.U1913601,U21A20479 and 62203441)+1 种基金in part by the Beijing Sci&Tech Program,China(No.Z211100007921021)in part by the Beijing Natural Science Foundation,China(No.Z170003).
文摘Rehabilitation assessment plays a vital role in the recovery process of post-stroke patients.Currently,many studies have focused on the implementation of automated assessment scales.However,the impact of stroke on the synergistic pattern between different human joints is not well understood.In this study,we developed an attention-coupled weighting based quantitative analysis model to identify the pathological alteration in the conjoint response structure between stroke patients and healthy participants,thus providing more intrinsic suggestions for the post-stroke rehabilitation training.In collaboration with the China Rehabilitation Research Center and the Macao University of Science and Technology,we recruited 15 post-stroke patients and 15 healthy participants to complete several actions selected from the Fugl-Meyer assessment(FMA)scale,which is a commonly used post-stroke rehabilitation assessment scale in clinical practice.Our study proposed an attentional coupling weight(ACW)extraction method.By filtering the weights in the attentional coupling network using a priori matrix,we can analyse the effect of stroke on the alteration of synergistic structures and the coordination patterns of the upper and lower extremities.Moreover,we used a commonly accepted synergy analysis method,the nonnegative matrix decomposition(NMF)method,for comparison and validation.The experimental results demonstrated the effectiveness of our method in quantifying the synergistic structure pattern alterations in post-stroke patients,which provides a new targeted option for the rehabilitation process.
基金supported by the National Key R&D Program of China(Grant No.2022YFC2408200)the National Natural Science Foundation of China(Grant No.52073014,No.52221006,No.82172428)+3 种基金Key Program of Beijing Natural Science Foundation(Grant No.Z200025)Fundamental Research Funds for the Central Universities(buctrc202020)Natural Science Foundation of Zhejiang Province(Grant No.LQN25H090021,LZ23H060001)BJAST Budding Talent Program(Grants No.23CE-BGS-02).
文摘Peripheral nerve injury presents a significant clinical challenge due to the limited regenerative capacity of the injured nerves,often resulting in permanent functional deficits.A key obstacle to effective nerve regeneration is the inability to modulate the inflammatory response,guide axonal elongation,and promote myelination.To address these challenges,we developed a multi-channel nerve guidance conduit(NGC)that integrated immune-modulating drug with gradient cues to enhance peripheral nerve regeneration.The inner tubes of the conduit were composed of degradable electrospun gelatin methacryloyl/collagen(GelMA/COL)fibers loaded with 1400W,an inducible nitric oxide synthase(iNOS)inhibitor.The outer tube consisted of electrospun polycaprolactone(PCL)fibers decorated with a density gradient of collagen particles encapsulating acidic fibroblast growth factor(aFGF).The release of 1400W enhanced macrophage activity and promoted their polarization from the pro-inflammatory M1 phenotype to the reparative M2 phenotype,thereby creating a pro-regenerative microenvironment conducive to nerve repair.The incorporation of gradient cues guided and promoted Schwann cell migration and neurite extension in vitro.In a rat sciatic nerve injury model,the conduit significantly improved nerve regeneration by sequentially modulating the inflammatory response and guiding axonal elongation,providing both spatial support and biological activity.Furthermore,the conduit promoted organized nerve fiber alignment,enhanced myelination,and achieved functional recovery outcomes that closely resembled those of the autograft.These findings suggest that the integration of immune-regulatory drug release,gradient cues,and a multi-channel structure presents a promising strategy for enhancing peripheral nerve repair.
基金This research was financially supported by the National Natural Science Foundation of China(No.22179054)the National Natural Science Foundation of China(No.22101150)+1 种基金Natural Science Foundation of Jiangsu Province,China(No.BK20190965)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.18KJB470011).
文摘Protonic ceramic fuel cells(PCFCs)are more suitable for operation at low temperatures due to their smaller activation energy(Ea).Unfortunately,the utilization of PCFC technology at reduced temperatures is limited by the lack of durable and high-activity air electrodes.A lot number of cobalt-based oxides have been developed as air electrodes for PCFCs,due to their high oxygen reduction reaction(ORR)activity.However,cobalt-based oxides usually have more significant thermal expansion coefficients(TECs)and poor thermomechanical compatibility with electrolytes.These characteristics can lead to cell delamination and degradation.Herein,we rationally design a novel cobalt-containing composite cathode material with the nominal composition of Sr_(4)Fe_(4)Co_(2)O_(13)+δ(SFC).SFC is composed of tetragonal perovskite phase(Sr_(8)Fe_(8)O_(23)+δ,I4/mmm,81 wt.%)and spinel phase(Co_(3)O_(4),Fd3m,19 wt.%).The SFC composite cathode displays an ultra-high oxygen ionic conductivity(0.053 S·cm^(-1)at 550℃),superior CO_(2)tolerance,and suitable TEC value(17.01×10^(-6)K^(-1)).SFC has both the O_(2)^(-)/e^(-)conduction function,and the triple conducting(H^(+)/O_(2)^(-)/e^(-))capability was achieved by introducing the protonic conduction phase(BaZr_(0.2)Ce_(0.7)Y_(0.1)O_(3-δ),BZCY)to form SFC+BZCY(70 wt.%:30 wt.%).The SFC+BZCY composite electrode exhibits superior ORR activity at a reduced temperature with extremely low area-specific resistance(ASR,0.677Ω·cm^(2)at 550℃),profound peak power density(PPD,535 mW·cm^(-2)and 1.065 V at 550℃),extraordinarily long-term durability(>500 h for symmetrical cell and 350 h for single cell).Moreover,the composite has an ultra-low TEC value(15.96×10^(-6)K^(-1)).This study proves that SFC+BZCY with triple conducting capacity is an excellent cathode for low-temperature PCFCs.
基金supported by the National Natural Science Foundation of China(No.22101029)the Beijing Natural Science Foundation(No.2222006)+2 种基金the Beijing Municipal Financial Project BJAST Scholar Programs B(No.BS202001)the Beijing Municipal Financial Project BJAST Young Scholar Programs B(No.YS202202)the Beijing Municipal Financial Project BJAST Budding Talent Program(No.23CE-BGS-01).
文摘The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8(ZIF-8)-based colloid particles(CPs)with an amorphous ZIF-8 skin.This encapsulation structure achieves an ultra-high loading rate(LR)of 90%(i.e.,9 mg doxorubicin(DOX)per 1 mg ZIF-8)for DOX and the protection of DOX from leaking.Notably,to deliver unit-dose drug,this ultra-high LR of 90%significantly reduces the usage of ZIF-8 to 1.2%(2 orders of magnitude)compared to that of DOX@ZIF-8 with a 10%LR,in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored.Safety,drug delivery efficacy,scale-up ability,and universality of this encapsulation structure have been further verified.Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.
基金supported in part by grants from the Beijing Natural Science Foundation of China(Grant No.7192123,7222117)the National Natural Science Foundation of China(Grant No.31770793,82000812)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2018122).
文摘As one of the main tumor-infiltrating immune cell types, tumor-associated macrophages (TAMs) determine the efficacy of immunotherapy. However, limited knowledge about their phenotypically and functionally heterogeneous nature restricts their application in tumor immunotherapy. In this study, we identified a subpopulation of CD146+ TAMs that exerted antitumor activity in both human samples and animal models. CD146 expression in TAMs was negatively controlled by STAT3 signaling. Reducing this population of TAMs promoted tumor development by facilitating myeloid-derived suppressor cell recruitment via activation of JNK signaling. Interestingly, CD146 was involved in the NLRP3 inflammasome-mediated activation of macrophages in the tumor microenvironment, partially by inhibiting transmembrane protein 176B (TMEM176B), an immunoregulatory cation channel. Treatment with a TMEM176B inhibitor enhanced the antitumor activity of CD146+ TAMs. These data reveal a crucial antitumor role of CD146+ TAMs and highlight the promising immunotherapeutic approach of inhibiting CD146 and TMEM176B.
基金the support of the National Key Research and Development Program of China(No.2022YFB4002502supported by the National Natural Science Foundation of China(Nos.22309067 and 22101150)+1 种基金the Open Project Program of the State Key Laboratory of Materials-Oriented Chemical Engineering(No.KL21-05)the Marine Equipment and Technology Institute,Jiangsu University of Science and Technology(No.XTCX202404).
文摘To enhance the performance and widespread use of solid oxide fuel cells(SOFCs),addressing the low-temperature(<650℃)electrochemical performance and operational stability issues of cathode materials is crucial.Here,we propose an innovative approach to enhance oxygen ion mobility and electrochemical performance of perovskite oxide by substituting some oxygen sites with chlorine anions.The designed SrTa_(0.1)Fe_(0.9)O_(3-δ-x)Clx(x=0.05 and 0.10)exhibits improved performance compared to SrTa_(0.1)Fe_(0.9)O_(3-δ)(STF).SrTa_(0.1)Fe_(0.9)O_(2.95-δ)Cl_(0.05)(STFCl0.05)shows the lowest area-specific resistance(ASR)value on Sm0.2Ce0.8O1.9(SDC)electrolyte.At 600℃,STFCl0.05 achieves an ASR value of 0.084Ω·cm^(2),and a single cell with STFCl0.05 reaches a higher peak power density(PPD)value(1143 mW·cm^(-2))than that with STF(672 mW·cm^(-2)).Additionally,besides exhibiting excellent oxygen reduction reaction(ORR)activity at lower temperatures,the STFCl0.05 cathode demonstrates good CO_(2)tolerance and operational stability.Symmetrical cell operation lasts for 150 h,and single cell operation endures for 720 h without significant performance decline.The chlorine doping approach effectively enhances ORR activity and stability,making STFCl0.05 a promising cathode material for low-temperature SOFCs.
基金This work was supported by the National Natural Science Foundation of China(Nos.22101029 and 21703219)Beijing Municipal Natural Science Foundation(No.2222006)+1 种基金Beijing Municipal Financial Project BJAST Scholar Programs B(No.BS202001)Beijing Municipal Financial Project BJAST Young Scholar Programs B(No.YS202202).
文摘There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calculations,the potential ofγ-graphyne(GY)as substrate for metals in the 4th and 5th periods under single-atom and dual-atoms concentration modes has been systematically investigated.It was found that single-atom Co,Ir,Rh,and Ru could effectively oxidate CO molecules,especially for single Rh.Furthermore,proper atoms concentration could boost the CO oxidation activity by supplying more reaction centers,such as Rh^(2)/GY.It was determined that two Rh atoms in Rh^(2)/GY act different roles in the catalytic reaction:one structural and another functional.Screening tests suggest that substituting the structural Rh atom in the center of acetylenic ring by Co or Cu atom is a possible way to maintain the reaction performance while reducing the noble metal cost.This systemic investigation will help in understanding the fundamental reaction mechanisms on GY-based substrates.We emphasize that properly exposed frontier orbital of functional metal atom is crucial in adsorption configuration as well as entire catalytic performance.This study constructs a workflow and provides valuable information for rational design of CO oxidation catalysts.
基金supported by the Fund for National Key R&D Program of China(No.2021YFC3200401)the National Natural Science Foundation of China(Nos.52170024,21677015,22006031).
文摘Plastic products widespread in natural water can be broken into smaller-sized microplastics(MPs,<5 mm)under light irradiation,thermal degradation and biodegradation,posing a serious threat to aquatic ecosystems and human health.This perspective concludes that MPs can generate reactive oxygen species(ROS)through initiation,propagation and termination steps,which can attack the polymer resulting in the photoaging and breakdown of C–C and C–H bonds under ultraviolet(UV)irradiation.Free radical generation and weathering degree of MPs depend on their physicochemical properties and environmental conditions.In general,UV irradiation and co-existed MPs can significantly accelerate MP photoaging.With plentiful chromophores carbonyl,carboxyl and benzene rings,Dissolved organic matter(DOM)mainly absorbs photons(300–500 nm)and generates hydrated electrons,^(3)DOM^(*) and ROS,which may affect MP photoaging.However,whether DOM may transfer the electron and energy to MPs under UV irradiation,affect ROS generation of MPs and their photoaging pathway are inadequately studied.More studies are needed to elucidate MP photoaging pathways and mechanisms,consider the influence of stabilization capacity,photosensitization and photoionization of DOM as well as their competitive light absorption with MPs,which provides valuable insights into the environmental behavior and ecological risk of MPs in natural water.
基金support from the National Natural Science Foundation of China(Nos.52222602,52201261)Beijing Nova Program(No.20220484170)+1 种基金Ningbo 3315 Innovative Teams Program(No.2019A-14-C)Fundamental Research Funds for the Central Universities(Nos.FRF-TP-22-001C1,FRF-EYIT-23-05).
文摘The revelation of thermal energy exchange mechanism of human body is challenging yet worthwhile,because it can clearly explain the changes in human symptoms and health status.Understanding,the heat transfer of the skin is significant because the skin is the foremost organ for the energy exchange between the human body and the environment.In order to diagnose the physiological conditions of human skin without causing any damage,it is necessary to use a non-invasive measurement technique by means of a conformal flexible sensor.The harmonic method can minimize the thermal-induced injury to the skin due to its low heat generating properties.A novel type of computational theory assessing skin thermal conductivity,blood perfusion rate of capillaries in the dermis,and superficial subcutaneous tissues was formed by combining the multi-medium thermal diffusion model and the bio-thermal model(Pennes equation).The skins of the hand back of six healthy subjects were measured.It was found that the results revealed no consistent changes in thermal conductivity were observed across genders and ages.The measured blood perfusion rates were within the range of human capillary flow.It was found that female subjects had a higher perfusion rate range(0.0058-0.0061 s^(-1))than male subjects(0.0032-0.0049 s^(-1)),which is consistent with invasive medical studies about the gender difference in blood flow rates and stimulated effects in relaxation situations.
基金granted by the National Natural Science Foundation of China(Nos.22309067 and 22279057)Financial Program of BJAST(No.25CA002).
文摘Symmetric solid oxide fuel cells(SSOFCs)have gained significant attention owing to their cost-effective fabrication,superior thermomechanical compatibility,and enhanced long-term stability.Ammonia(NH_(3)),an excellent hydrogen carrier,is a promising clean energy source with high energy density,easy transportation and storage.Notably,NH_(3) contained only nitrogen and hydrogen,making it carbon-free.In this study,we synthesize the highly active symmetric electrode material Pr_(0.32)Sr_(0.48)Fe_(0.75)Ni_(0.2)Ru_(0.05)O_(3-δ)(PSFNRu)by replacing partial Fe in Pr_(0.32)Sr_(0.48)Fe_(0.8)Ni_(0.2)O_(3-δ)(PSFN)with 5 mol%Ru.PSFNRu possesses a sufficient quantity of oxygen vacancies,with the capacity to in-situ exsolved alloy nanoparticles(ANPs)in a reducing atmosphere.This nanocomposite is found to promote electrochemical reactions.For example,at 800℃,the SSOFC employing the PSFNRu electrode achieves a peak power density(PPD)of 736 mW·cm^(-2) when using hydrogen(H_(2))as the fuel.Under NH_(3) conditions,the cell delivers a PPD of 547 mW·cm^(-2),significantly surpassing the 462 mW·cm^(-2) recorded for a comparable cell employing the PSFN electrode.The enhanced cell performance is mainly ascribed to Ru doping,which boosts the ORR activity and facilitates the in-situ exsolution of ANPs at the anode,increasing active sites and accelerating NH_(3) decomposition.In addition,remarkable operational stability of the single cell(172 h under NH_(3) fuel at 700℃)is also demonstrated.These encouraging experimental results highlight the superiority of PSFNRu as the bi-functional electrodes for direct ammonia symmetric solid oxide fuel cells(DA-SSOFCs),and providing a potential and reliable pathway towards accelerating the development of DA-SSOFCs.
基金the National Natural Science Foundation of China(No.21971002)the Natural Science Foundation of Anhui Province(Nos.1908085QB45 and 2008085QB81)。
文摘High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance,but still challenging.Herein,a new strategy,consisting of using diatomic synergistic modulation(DSM)to effectively control the separation of photo-generated carriers for an enhanced production of phenol is reported.The atomic level dispersion of Fe and Cr respectively decorated on Al based MIL-53-NH_(2)photocatalyst(Fe1/Cr:MIL-53-NH_(2))is designed,in which Cr single atoms are substituted for Al3+while Fe single atoms are coordinated by N.Notably,the Fe1/Cr:MIL-53-NH_(2)significantly boosts the photooxidation of benzene to phenol under visible light irradiation,which is much higher than those of MIL-53-NH_(2),Cr:MIL-53-NH_(2),Fe1/MIL-53-NH_(2),and Fe nanoparticles/Cr:MIL-53-NH_(2)catalysts.Theoretical and experimental results reveal that the Cr single atoms and Fe single atoms can act as electron acceptor and electron donor,respectively,during photocatalytic reaction,exhibiting a synergistic effect on the separation of the photo-generated carriers and thereby causing great enhancement on the benzene oxidation.This strategy provides new insights for rational design of advanced photocatalysts at the atomic level.
