Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalizedπelectrons along the molecular chain framework.Up to date,origin of insulating polymer regulated charge transfer has...Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalizedπelectrons along the molecular chain framework.Up to date,origin of insulating polymer regulated charge transfer has not yet been uncovered.In this work,we unleash the root origin of charge transport capability of insulating polymer in photocatalysis.We ascertain that insulating polymer plays crucial roles in fine tuning of electronic structure of transition metal chalcogenides(TMCs),which mainly include altering surface electron density of TMCs for accelerating charge transport kinetics,triggering the generation of defect over TMCs for prolonging carrier lifetime,and acting as hole-trapping mediator for retarding charge recombination.These synergistic roles contribute to the charge transfer of insulating polymer.Our work opens a new vista of utilizing solid insulating polymers for maneuvering charge transfer toward solar energy conversion.展开更多
Pt based materials are the most efficient electrocatalysts for the oxygen reduction reaction(ORR)and methanol oxidation reaction(MOR)in fuel cells.Maximizing the utilization of Pt based materials by modulating their m...Pt based materials are the most efficient electrocatalysts for the oxygen reduction reaction(ORR)and methanol oxidation reaction(MOR)in fuel cells.Maximizing the utilization of Pt based materials by modulating their morphologies to expose more active sites is a fundamental objective for the practical application of fuel cells.Herein,we report a new class of hierarchically skeletal Pt-Ni nanocrystals(HSNs)with a multi-layered structure,prepared by an inorganic acid-induced solvothermal method.The addition of H_(2)SO_(4)to the synthetic protocol provides a critical trigger for the successful growth of Pt-Ni nanocrystals with the desired structure.The Pt-Ni HSNs synthesized by this method exhibit enhanced mass activity of 1.25 A mgpt−1 at 0.9 V(versus the reversible hydrogen electrode)towards ORR in 0.1-M HClO_(4),which is superior to that of Pt-Ni multi-branched nanocrystals obtained by the same method in the absence of inorganic acid;it is additionally 8.9-fold higher than that of the commercial Pt/C catalyst.Meanwhile,it displays enhanced stability,with only 21.6%mass activity loss after 10,000 cycles(0.6–1.0 V)for ORR.Furthermore,the Pt-Ni HSNs show enhanced activity and anti-toxic ability in CO for MOR.The superb activity of the Pt-Ni HSNs for ORR and MOR is fully attributed to an extensively exposed electrochemical surface area and high intrinsic activity,induced by strain effects,provided by the unique hierarchically skeletal alloy structure.The novel open and hierarchical structure of Pt-Ni alloy provides a promising approach for significant improvements of the activity of Pt based alloy electrocatalysts.展开更多
Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electric...Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide （GO） self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide （rGO） aerogel samples exhibited densities as low as 1.1 mg·cm^-3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus （E） scaled with density （p） as E-p^2. The rGO aerogels also exhibited high conductivities （e.g., 27.7 S·m^-1 at 3.6 mg·cm^-3） and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.展开更多
The design of selective and efficient covalent organic frameworks(COFs)based electrocatalysts with tunable morphology for efficient CO_(2) reduction reaction(CO_(2)RR)to CH_(4) is highly desirable.Here,two kinds of an...The design of selective and efficient covalent organic frameworks(COFs)based electrocatalysts with tunable morphology for efficient CO_(2) reduction reaction(CO_(2)RR)to CH_(4) is highly desirable.Here,two kinds of anthraquinone-based COFs(i.e.,AAn-COF and OH-AAn-COF)with tunable 1D superstructures(e.g.,nanofibers(NF)and hollow tubes(HT))have been produced via Schiff-base condensation reaction.Interestingly,a rarely reported nanosheet-based self-template mechanism and a nanosheet-crimping mechanism have been demonstrated for the production of COF-based nanofibers and hollow tubes,respectively.Besides,the obtained COF-based superstructures can be post-modified with transition metals for efficient CO_(2)RR.Specifically,AAn-COF-Cu(NF)and OH-AAn-COF-Cu(HT)exhibit superior faradaic-efficiency with CH_(4)(FECH_(4))of 77%(-128.1 mA cm^(-2),-0.9 V)and 61%(-99.5 mA cm^(-2),-1.0 V)in a flow-cell,respectively.Noteworthy,the achieved FECH_(4) of AAn-COF-Cu(NF)(77%)is the highest one among reported crystalline COFs.This work provides a general methodology in exploring morphology-controlled COFs for electrocatalytic CO_(2)RR.展开更多
Stimuli-responsive drug delivery systems based on polymeric micelles can achieve controlled drug release to improve the therapeutic outcome and reduce unwanted systematic toxicity and side effects of the cytotoxic dru...Stimuli-responsive drug delivery systems based on polymeric micelles can achieve controlled drug release to improve the therapeutic outcome and reduce unwanted systematic toxicity and side effects of the cytotoxic drug in chemotherapy but often face challenging synthesis and purification of functionalized biocompatible polymer materials and low drug loading efficiency. In the present study, we reported a novel redox-responsive self-assembly polymeric micelle system, mPEG-β-CD/Ad-SS-CPT, to achieve high loading efficiency and selective delivery of camptothecin(CPT) in a reductive environment inside cancer cells. The host-guest supramolecular micelles utilized a simple β-CD modified PEG, mPEG-β-cyclodextrin(mPEG-β-CD), as the polymeric host with the ease of synthesis and purification. The guest prodrug Ad-SS-CPT contained the disulfide bond as the redox sensitivity group. The selective cleavage of disulfide bond and subsequent drug release in a reductive environment could potentially reduce system toxicity and improve the therapeutic outcome of CPT. In vitro studies showed that the micelles exhibited excellent cytotoxicity against He La cells comparable to the free drug. The host-guest polymeric micelles also showed great potentials for multi-drug co-delivery. Collectively, our current findings provided a general and convenient approach to design drug delivery systems based on stimuli-responsive polymeric micelles for disease treatment.展开更多
文摘Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalizedπelectrons along the molecular chain framework.Up to date,origin of insulating polymer regulated charge transfer has not yet been uncovered.In this work,we unleash the root origin of charge transport capability of insulating polymer in photocatalysis.We ascertain that insulating polymer plays crucial roles in fine tuning of electronic structure of transition metal chalcogenides(TMCs),which mainly include altering surface electron density of TMCs for accelerating charge transport kinetics,triggering the generation of defect over TMCs for prolonging carrier lifetime,and acting as hole-trapping mediator for retarding charge recombination.These synergistic roles contribute to the charge transfer of insulating polymer.Our work opens a new vista of utilizing solid insulating polymers for maneuvering charge transfer toward solar energy conversion.
文摘Pt based materials are the most efficient electrocatalysts for the oxygen reduction reaction(ORR)and methanol oxidation reaction(MOR)in fuel cells.Maximizing the utilization of Pt based materials by modulating their morphologies to expose more active sites is a fundamental objective for the practical application of fuel cells.Herein,we report a new class of hierarchically skeletal Pt-Ni nanocrystals(HSNs)with a multi-layered structure,prepared by an inorganic acid-induced solvothermal method.The addition of H_(2)SO_(4)to the synthetic protocol provides a critical trigger for the successful growth of Pt-Ni nanocrystals with the desired structure.The Pt-Ni HSNs synthesized by this method exhibit enhanced mass activity of 1.25 A mgpt−1 at 0.9 V(versus the reversible hydrogen electrode)towards ORR in 0.1-M HClO_(4),which is superior to that of Pt-Ni multi-branched nanocrystals obtained by the same method in the absence of inorganic acid;it is additionally 8.9-fold higher than that of the commercial Pt/C catalyst.Meanwhile,it displays enhanced stability,with only 21.6%mass activity loss after 10,000 cycles(0.6–1.0 V)for ORR.Furthermore,the Pt-Ni HSNs show enhanced activity and anti-toxic ability in CO for MOR.The superb activity of the Pt-Ni HSNs for ORR and MOR is fully attributed to an extensively exposed electrochemical surface area and high intrinsic activity,induced by strain effects,provided by the unique hierarchically skeletal alloy structure.The novel open and hierarchical structure of Pt-Ni alloy provides a promising approach for significant improvements of the activity of Pt based alloy electrocatalysts.
基金This work was supported Foundation for Returned Education of China, Key by the Scientific Research Scholars, the Ministry of Basic Research Projects of Science and Technology Commission of Shanghai （No.11JC1412900）, and the National Science Foundation of China program （Nos. 21271140, 51472182）.
文摘Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide （GO） self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide （rGO） aerogel samples exhibited densities as low as 1.1 mg·cm^-3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus （E） scaled with density （p） as E-p^2. The rGO aerogels also exhibited high conductivities （e.g., 27.7 S·m^-1 at 3.6 mg·cm^-3） and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.
基金supported by the National Natural Science Foundation of China(21871141,21871142,21901122,22071109 and 92061101)the Natural Science Research of Jiangsu Higher Education Institutions of China(19KJB150011)+3 种基金China Postdoctoral Science Foundation(2018M630572 and 2019M651873)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX201171)Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Foundation of Jiangsu Collaborative Innovation Center of Biomedical Functional Materials.
文摘The design of selective and efficient covalent organic frameworks(COFs)based electrocatalysts with tunable morphology for efficient CO_(2) reduction reaction(CO_(2)RR)to CH_(4) is highly desirable.Here,two kinds of anthraquinone-based COFs(i.e.,AAn-COF and OH-AAn-COF)with tunable 1D superstructures(e.g.,nanofibers(NF)and hollow tubes(HT))have been produced via Schiff-base condensation reaction.Interestingly,a rarely reported nanosheet-based self-template mechanism and a nanosheet-crimping mechanism have been demonstrated for the production of COF-based nanofibers and hollow tubes,respectively.Besides,the obtained COF-based superstructures can be post-modified with transition metals for efficient CO_(2)RR.Specifically,AAn-COF-Cu(NF)and OH-AAn-COF-Cu(HT)exhibit superior faradaic-efficiency with CH_(4)(FECH_(4))of 77%(-128.1 mA cm^(-2),-0.9 V)and 61%(-99.5 mA cm^(-2),-1.0 V)in a flow-cell,respectively.Noteworthy,the achieved FECH_(4) of AAn-COF-Cu(NF)(77%)is the highest one among reported crystalline COFs.This work provides a general methodology in exploring morphology-controlled COFs for electrocatalytic CO_(2)RR.
基金National Key Research and Development Program of China (Grant No. 2019YFA0904800)Science and Technology Commission of Shanghai Municipality (Grant No. 11DZ2260600 and 10DZ2220500)Shanghai Natural Science Fund (Grant No. 20ZR1414700)。
文摘Stimuli-responsive drug delivery systems based on polymeric micelles can achieve controlled drug release to improve the therapeutic outcome and reduce unwanted systematic toxicity and side effects of the cytotoxic drug in chemotherapy but often face challenging synthesis and purification of functionalized biocompatible polymer materials and low drug loading efficiency. In the present study, we reported a novel redox-responsive self-assembly polymeric micelle system, mPEG-β-CD/Ad-SS-CPT, to achieve high loading efficiency and selective delivery of camptothecin(CPT) in a reductive environment inside cancer cells. The host-guest supramolecular micelles utilized a simple β-CD modified PEG, mPEG-β-cyclodextrin(mPEG-β-CD), as the polymeric host with the ease of synthesis and purification. The guest prodrug Ad-SS-CPT contained the disulfide bond as the redox sensitivity group. The selective cleavage of disulfide bond and subsequent drug release in a reductive environment could potentially reduce system toxicity and improve the therapeutic outcome of CPT. In vitro studies showed that the micelles exhibited excellent cytotoxicity against He La cells comparable to the free drug. The host-guest polymeric micelles also showed great potentials for multi-drug co-delivery. Collectively, our current findings provided a general and convenient approach to design drug delivery systems based on stimuli-responsive polymeric micelles for disease treatment.
