The inadequate performance of oxygen reduction reaction(ORR)catalysts hampers the development of proton exchange membrane fuel cells(PEMFCs).Herein,we proposed an approach to tackle this problem by modulating the chem...The inadequate performance of oxygen reduction reaction(ORR)catalysts hampers the development of proton exchange membrane fuel cells(PEMFCs).Herein,we proposed an approach to tackle this problem by modulating the chemical bond type of intermetallic Pt-based catalysts,using phosphorus(P)doped L1_(0)-PtFeGa_(0.1)/C(P-L1_(0)-PtFeGa_(0.1)/C)as a proof of concept.X-ray absorption spectroscopy(XAS)demonstrated that the doped P transferred electrons to Pt,and thus,modified the electronic structure of Pt,weakening the adsorption strength with oxygen-containing species.Therefore P-L1_(0)-PtFeGa_(0.1)/C showed 13 times mass activity(MA)compared with commercial Pt/C,with a decay of only 28%after 100,000 potential cycles.When equipped in the membrane electrode assembly,the P-L1_(0)-PtFeGa_(0.1)/C catalyst also exhibited a remarkable activity(MA=0.84 A mgPt^(−1)at 0.9 V)and stability(MA retention=72%and voltage loss=9 mVat 0.8 A cm^(−2)after 30,000 cycles),making it one of the best performers among recorded Pt-based catalysts.Theoretical studies demonstrated that the doping of P optimized the adsorption energy between Pt and oxygen intermediates through sp-d orbital interactions and prevented metal dissolution by forming stronger Pt-P covalent bonds compared with Pt–Pt bonds.展开更多
Si is a promising anode material for lithium-ion batteries owing to its high theoretical capacity.How-ever,large stress during(de)lithiation induces severe structural pulverization,electrical contact failure,and unsta...Si is a promising anode material for lithium-ion batteries owing to its high theoretical capacity.How-ever,large stress during(de)lithiation induces severe structural pulverization,electrical contact failure,and unstable solid-electrolyte interface,which hampers the practical application of Si anode.Herein,a Si-based anode with a hierarchical pomegranate-structure(HPS-Si)was designed to modulate the stress variation,and a sub-micronized Si-based sphere was assembled by the nano-sized Si nanospheres with sub-nanometer-sized multi-phase modification of the covalently linked SiO_(2-x),SiC,and carbon.The sub-micronized HPS-Si stacked with Si nanospheres can avoid agglomerates during cycling due to the high surface energy of nanomaterials.Meanwhile,the reasonable pore structure from SiO_(2) reduction owing to density difference is enough to accommodate the limited volume expansion.The Si spheres with a size of about 50 nm can prevent self-cracking.SiO_(2-x),and SiC as flexible and rigid layers,have been syner-gistically used to reduce the surface stress of conductive carbon layers to avoid cracking.The covalent bonding immensely strengthens the link of the modification with Si nanospheres,thus resisting stress effects.Consequently,a full cell comprising an HPS-Si anode and a LiCoO_(2) cathode achieved an energy density of 415 Wh kg^(-1) with a capacity retention ratio of 87.9%after 300 cycles based on the active ma-terials.It is anticipated that the hierarchical pomegranate-structure design can provide inspiring insights for further studies of the practical application of silicon anode.展开更多
Reactive oxygen species(ROS)are byproducts of cellular metabolism;they play a significant role as secondary messengers in cell signaling.In cells,high concentrations of ROS induce apoptosis,senescence,and contact inhi...Reactive oxygen species(ROS)are byproducts of cellular metabolism;they play a significant role as secondary messengers in cell signaling.In cells,high concentrations of ROS induce apoptosis,senescence,and contact inhibition,while low concentrations of ROS result in angiogenesis,proliferation,and cytoskeleton remodeling.Thus,controlling ROS generation is an important factor in cell biology.We designed a chlorin e6(Ce6)-immobilized polyethylene terephthalate(PET)film(Ce6-PET)to produce extracellular ROS under red-light irradiation.The application of Ce6-PET films can regulate the generation of ROS by altering the intensity of light-emitting diode sources.We confirmed that the Ce6-PET film could effectively promote cell growth under irradiation at 500 μW/cm^(2) for 30 min in human umbilical vein endothelial cells.We also found that the Ce6-PET film is more efficient in generating ROS than a Ce6-incorporated polyurethane film under the same conditions.Ce6-PET fabrication shows promise for improving the localized delivery of extracellular ROS and regulating ROS formation through the optimization of irradiation intensity.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,grant nos.22122202 and 22072051)Zhenjiang Key Research and Development Program,Industry Foresight and Common Key Technologies,China(grant no.CQ2022006).
文摘The inadequate performance of oxygen reduction reaction(ORR)catalysts hampers the development of proton exchange membrane fuel cells(PEMFCs).Herein,we proposed an approach to tackle this problem by modulating the chemical bond type of intermetallic Pt-based catalysts,using phosphorus(P)doped L1_(0)-PtFeGa_(0.1)/C(P-L1_(0)-PtFeGa_(0.1)/C)as a proof of concept.X-ray absorption spectroscopy(XAS)demonstrated that the doped P transferred electrons to Pt,and thus,modified the electronic structure of Pt,weakening the adsorption strength with oxygen-containing species.Therefore P-L1_(0)-PtFeGa_(0.1)/C showed 13 times mass activity(MA)compared with commercial Pt/C,with a decay of only 28%after 100,000 potential cycles.When equipped in the membrane electrode assembly,the P-L1_(0)-PtFeGa_(0.1)/C catalyst also exhibited a remarkable activity(MA=0.84 A mgPt^(−1)at 0.9 V)and stability(MA retention=72%and voltage loss=9 mVat 0.8 A cm^(−2)after 30,000 cycles),making it one of the best performers among recorded Pt-based catalysts.Theoretical studies demonstrated that the doping of P optimized the adsorption energy between Pt and oxygen intermediates through sp-d orbital interactions and prevented metal dissolution by forming stronger Pt-P covalent bonds compared with Pt–Pt bonds.
基金support by the NSFC Nos.51972156,51872131,51672117,51672118,22209055CPSF No.2022M721330Distin-guished Professor of Liaoning Province(2017)are acknowledged.
文摘Si is a promising anode material for lithium-ion batteries owing to its high theoretical capacity.How-ever,large stress during(de)lithiation induces severe structural pulverization,electrical contact failure,and unstable solid-electrolyte interface,which hampers the practical application of Si anode.Herein,a Si-based anode with a hierarchical pomegranate-structure(HPS-Si)was designed to modulate the stress variation,and a sub-micronized Si-based sphere was assembled by the nano-sized Si nanospheres with sub-nanometer-sized multi-phase modification of the covalently linked SiO_(2-x),SiC,and carbon.The sub-micronized HPS-Si stacked with Si nanospheres can avoid agglomerates during cycling due to the high surface energy of nanomaterials.Meanwhile,the reasonable pore structure from SiO_(2) reduction owing to density difference is enough to accommodate the limited volume expansion.The Si spheres with a size of about 50 nm can prevent self-cracking.SiO_(2-x),and SiC as flexible and rigid layers,have been syner-gistically used to reduce the surface stress of conductive carbon layers to avoid cracking.The covalent bonding immensely strengthens the link of the modification with Si nanospheres,thus resisting stress effects.Consequently,a full cell comprising an HPS-Si anode and a LiCoO_(2) cathode achieved an energy density of 415 Wh kg^(-1) with a capacity retention ratio of 87.9%after 300 cycles based on the active ma-terials.It is anticipated that the hierarchical pomegranate-structure design can provide inspiring insights for further studies of the practical application of silicon anode.
基金This work was supported by a National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT,Nos 2017M3A9B3063638 and 2019R1A2C2005256).
文摘Reactive oxygen species(ROS)are byproducts of cellular metabolism;they play a significant role as secondary messengers in cell signaling.In cells,high concentrations of ROS induce apoptosis,senescence,and contact inhibition,while low concentrations of ROS result in angiogenesis,proliferation,and cytoskeleton remodeling.Thus,controlling ROS generation is an important factor in cell biology.We designed a chlorin e6(Ce6)-immobilized polyethylene terephthalate(PET)film(Ce6-PET)to produce extracellular ROS under red-light irradiation.The application of Ce6-PET films can regulate the generation of ROS by altering the intensity of light-emitting diode sources.We confirmed that the Ce6-PET film could effectively promote cell growth under irradiation at 500 μW/cm^(2) for 30 min in human umbilical vein endothelial cells.We also found that the Ce6-PET film is more efficient in generating ROS than a Ce6-incorporated polyurethane film under the same conditions.Ce6-PET fabrication shows promise for improving the localized delivery of extracellular ROS and regulating ROS formation through the optimization of irradiation intensity.
