Three-dimensional （3D） hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along （111, 110）,...Three-dimensional （3D） hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along （111, 110）, （111）, and （100） planes, respectively. These structures have been characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, energy dispersive X-ray spectroscopy （EDX）, inductively coupled plasma optical emission spectrometry （ICP-OES） and a detailed formation mechanism has been developed, which shows that the in situ formed 12 and the galvanic replacement reaction between Cu and Pt4, may guide the formation of these superstructures. The comparative electrocatalytic properties have been investigated for methanol and ethanol oxidation. Due to their interconnected arms, sufficient absorption sites, and exposed surfaces, these superstructures exhibit enhanced electrocatalytic performance for electro-oxidation of methanol and ethanol when compared with commercial Pt/C and Pt black.展开更多
In_(2)O_(3)is an effective electrocatalyst to convert CO_(2)to formic acid(HCOOH),but its inherent poor electrical conductivity limits the efficient charge transfer during the reaction.Additionally,the tendency of In_...In_(2)O_(3)is an effective electrocatalyst to convert CO_(2)to formic acid(HCOOH),but its inherent poor electrical conductivity limits the efficient charge transfer during the reaction.Additionally,the tendency of In_(2)O_(3)particles to agglomerate during synthesis further limits the exposure of active sites.Here we address these issues by leveraging the template effect of graphene oxide and employing InBDC as a self-sacrificing template for the pyrolysis synthesis of In_(2)O_(3)@C.The resulting In_(2)O_(3)@C/rGO-600 material features In_(2)O_(3)@C nanocubes uniformly anchored on a support of reduced graphene oxide(rGO),significantly enhancing the active sites exposure.The conductive rGO network facilitates charge transfer during electrocatalysis,and the presence of oxygen vacancies generated during pyrolysis,combined with the strong electron-donating ability of rGO,enhances the adsorption and activation of CO_(2).In performance evaluation,In_(2)O_(3)@C/rGO-600 exhibits a remarkable HCOOH Faradaic efficiency exceeding 94.0%over a broad potential window of−0.7 to−1.0 V(vs.reversible hydrogen electrode(RHE)),with the highest value of 97.9%at−0.9 V(vs.RHE)in a H-cell.Moreover,the material demonstrates an excellent cathodic energy efficiency of 71.6%at−0.7 V(vs.RHE).The study underscores the efficacy of uniformly anchoring metal oxide nanoparticles onto rGO for enhancing the electrocatalytic CO_(2)reduction performance of materials.展开更多
Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene se...Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene semi-hydrogenation as a model reaction,here we explore the optimization approaches toward better Pd catalysts for alkyne semi-hydrogenation through investigating support effect and metal-support interactions.The results show that the states of Pd with supports can be tuned by varying oxide reducibility,loading ratios,and post-treatments.In our system,0.06 wt.%Pd on rutile-TiO_(2) nanorods shows the highest activity owing to the synergistic effects of single-atoms and clusters.Support reducibility can change the filling degrees of Pd 4d orbitals through varying interfacial bonding strengths,which further affect catalytic activity and selectivity.展开更多
Stable and bioactive material-tissue interface(MTF)basically determines the clinical applications of biomaterials in wound healing,sustained drug release,and tissue engineering.Although many inorganic nanomaterials ha...Stable and bioactive material-tissue interface(MTF)basically determines the clinical applications of biomaterials in wound healing,sustained drug release,and tissue engineering.Although many inorganic nanomaterials have been widely explored to enhance the stability and bioactivity of polymer-based biomaterials,most are still restricted by their stability and biocompatibility.Here we demonstrate the enhanced bioactivity and stability of polymer-matrix bio-composite through coupling multiscale material-tissue interfacial interactions with atomically thin TiO_(2)nanosheets.Resin modified with TiO_(2)nanosheets displays improved mechanical properties,hydrophilicity,and stability.Also,we confirm that this resin can effectively stimulate the adhesion,proliferation,and differentiation into osteogenic and odontogenic lineages of human dental pulp stem cells using in vitro cell-resin interface model.TiO_(2)nanosheets can also enhance the interaction between demineralized dentinal collagen and resin.Our results suggest an approach to effectively up-regulate the stability and bioactivity of MTFs by designing biocompatible materials at the sub-nanoscale.展开更多
Size reduction can generally enhance the surface reactivity of inorganic nanomaterials.The origin of this nano-effect has been ascribed to ultrasmall size,large specific surface area,or abundant defects,but the most i...Size reduction can generally enhance the surface reactivity of inorganic nanomaterials.The origin of this nano-effect has been ascribed to ultrasmall size,large specific surface area,or abundant defects,but the most intrinsic electronic-level principles are still not fully understood yet.By combining experimental explorations and mathematical modeling,herein we propose an electronic-level model to reveal the physicochemical nature of size-dependent nanomaterial surface reactivity.Experimentally,we reveal that competitive redistribution of surface atomic orbitals from extended energy band states into localized surface chemical bonds is the critical electronic process of surface chemical interactions,using H_(2)O_(2)-TiO_(2)chemisorption as a model reaction.Theoretically,we define a concept,orbital potential(G),to describe the electronic feature determining the tendency of orbital redistribution,and deduce a mathematical model to reveal how size modulates surface reactivity.We expose the dual roles of size reduction in enhancing nanomaterial surface reactivity-inversely correlating to orbital potential and amplifying the effects of other structural factors on surface reactivity.展开更多
基金This work was supported by the National Natural Science Foundation of China （Nos. 91127040 and 21221062）, and the State Key Project of Fundamental Research for Nanoscience and Nanotechnology （No. 2011CB932402）.
文摘Three-dimensional （3D） hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along （111, 110）, （111）, and （100） planes, respectively. These structures have been characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, energy dispersive X-ray spectroscopy （EDX）, inductively coupled plasma optical emission spectrometry （ICP-OES） and a detailed formation mechanism has been developed, which shows that the in situ formed 12 and the galvanic replacement reaction between Cu and Pt4, may guide the formation of these superstructures. The comparative electrocatalytic properties have been investigated for methanol and ethanol oxidation. Due to their interconnected arms, sufficient absorption sites, and exposed surfaces, these superstructures exhibit enhanced electrocatalytic performance for electro-oxidation of methanol and ethanol when compared with commercial Pt/C and Pt black.
基金Joint Key Program of National Natural Science Foundation of China(No.U22B20147).
文摘In_(2)O_(3)is an effective electrocatalyst to convert CO_(2)to formic acid(HCOOH),but its inherent poor electrical conductivity limits the efficient charge transfer during the reaction.Additionally,the tendency of In_(2)O_(3)particles to agglomerate during synthesis further limits the exposure of active sites.Here we address these issues by leveraging the template effect of graphene oxide and employing InBDC as a self-sacrificing template for the pyrolysis synthesis of In_(2)O_(3)@C.The resulting In_(2)O_(3)@C/rGO-600 material features In_(2)O_(3)@C nanocubes uniformly anchored on a support of reduced graphene oxide(rGO),significantly enhancing the active sites exposure.The conductive rGO network facilitates charge transfer during electrocatalysis,and the presence of oxygen vacancies generated during pyrolysis,combined with the strong electron-donating ability of rGO,enhances the adsorption and activation of CO_(2).In performance evaluation,In_(2)O_(3)@C/rGO-600 exhibits a remarkable HCOOH Faradaic efficiency exceeding 94.0%over a broad potential window of−0.7 to−1.0 V(vs.reversible hydrogen electrode(RHE)),with the highest value of 97.9%at−0.9 V(vs.RHE)in a H-cell.Moreover,the material demonstrates an excellent cathodic energy efficiency of 71.6%at−0.7 V(vs.RHE).The study underscores the efficacy of uniformly anchoring metal oxide nanoparticles onto rGO for enhancing the electrocatalytic CO_(2)reduction performance of materials.
基金supported by the National Natural Science Foundation of China(No.21801012 to G.L.X.).
文摘Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene semi-hydrogenation as a model reaction,here we explore the optimization approaches toward better Pd catalysts for alkyne semi-hydrogenation through investigating support effect and metal-support interactions.The results show that the states of Pd with supports can be tuned by varying oxide reducibility,loading ratios,and post-treatments.In our system,0.06 wt.%Pd on rutile-TiO_(2) nanorods shows the highest activity owing to the synergistic effects of single-atoms and clusters.Support reducibility can change the filling degrees of Pd 4d orbitals through varying interfacial bonding strengths,which further affect catalytic activity and selectivity.
基金supported by the National Natural Science Foundation of China(Nos.82001110,82071154,21801012,81720108011,81470773,and 81571013).
文摘Stable and bioactive material-tissue interface(MTF)basically determines the clinical applications of biomaterials in wound healing,sustained drug release,and tissue engineering.Although many inorganic nanomaterials have been widely explored to enhance the stability and bioactivity of polymer-based biomaterials,most are still restricted by their stability and biocompatibility.Here we demonstrate the enhanced bioactivity and stability of polymer-matrix bio-composite through coupling multiscale material-tissue interfacial interactions with atomically thin TiO_(2)nanosheets.Resin modified with TiO_(2)nanosheets displays improved mechanical properties,hydrophilicity,and stability.Also,we confirm that this resin can effectively stimulate the adhesion,proliferation,and differentiation into osteogenic and odontogenic lineages of human dental pulp stem cells using in vitro cell-resin interface model.TiO_(2)nanosheets can also enhance the interaction between demineralized dentinal collagen and resin.Our results suggest an approach to effectively up-regulate the stability and bioactivity of MTFs by designing biocompatible materials at the sub-nanoscale.
基金This research was supported by the National Natural Science Foundation of China(No.21801012).
文摘Size reduction can generally enhance the surface reactivity of inorganic nanomaterials.The origin of this nano-effect has been ascribed to ultrasmall size,large specific surface area,or abundant defects,but the most intrinsic electronic-level principles are still not fully understood yet.By combining experimental explorations and mathematical modeling,herein we propose an electronic-level model to reveal the physicochemical nature of size-dependent nanomaterial surface reactivity.Experimentally,we reveal that competitive redistribution of surface atomic orbitals from extended energy band states into localized surface chemical bonds is the critical electronic process of surface chemical interactions,using H_(2)O_(2)-TiO_(2)chemisorption as a model reaction.Theoretically,we define a concept,orbital potential(G),to describe the electronic feature determining the tendency of orbital redistribution,and deduce a mathematical model to reveal how size modulates surface reactivity.We expose the dual roles of size reduction in enhancing nanomaterial surface reactivity-inversely correlating to orbital potential and amplifying the effects of other structural factors on surface reactivity.
