The design and syntheses of metal-organic cages(MOCs)based on polyoxometalates(POMs)building blocks have attracted increasing attention due to their intriguing molecular architectures and physicochemical properties.In...The design and syntheses of metal-organic cages(MOCs)based on polyoxometalates(POMs)building blocks have attracted increasing attention due to their intriguing molecular architectures and physicochemical properties.In this work,we have successfully synthesized and systematically characterized a tetrahedral polyoxometalate-based organic cage(POC),K_(3)Na_(17)H_(12)[(C_(4)H_(6)O_(6))_(6)[Ni_(4)(OH)_(3)(A-α-SiW_(9)O_(34))]_(4)]·96H_(2)O(Ni_(16)L_(6)(SiW_(9))_(4)),using tritopic Ni_(4)-substituted Keggin cluster(Ni_(4)SiW_(9))as nodes and flexible L-(+)-tartaric acid ligands as linkers.The resulting POC tetrahedron has been firstly investigated as efficient catalyst for visible-light-driven hydrogen production,achieving a turnover number of 15,500 after 96-h photocatalysis.Such high catalytic performance of Ni_(16)L_(6)(SiW_(9))_(4)POC catalyst could be attributed to its unique cage structure,thereby offering more efficient catalytic component accessibility.In addition,spectroscopic analyses illustrated the photocatalytic mechanism and the structural stability of the TBA-Ni_(16)L_(6)(SiW_(9))_(4)catalyst during the photocatalytic process.展开更多
The development of bifunctional catalysts for solar-driven hydrogen and oxygen evolution has been regarded as a challenging but interesting research topic.As promising multi-electron-transfer catalysts,previously repo...The development of bifunctional catalysts for solar-driven hydrogen and oxygen evolution has been regarded as a challenging but interesting research topic.As promising multi-electron-transfer catalysts,previously reported polyoxometalate(POM)-based catalysts often contain only a single type of transition metal substitution for driving either hydrogen production or oxygen evolution.Herein,a viable two-step parental substitution approach has been developed to synthesize two structurally-new mixed-transition-metal-substituted polyoxometalates(mixed TMSPs),K_(6)Na_(4)[Mn_(2)Ni_(2)(H_(2)O)2(PW_(9)O_(34))2]·21H_(2)O({Mn_(2)Ni_(2)})and K10[Mn_(2)Co_(2)(H_(2)O)2(PW_(9)O_(34))2]·35H_(2)O({Mn_(2)Co_(2)}),using Na_(12)[Mn_(2)Na_(2)(PW_(9)O_(34))2]·36H_(2)O({Mn_(2)Na_(2)})as the precursor.Characterization results confirmed the nearly quantitative substitution of Na+with Ni_(2)+and Co_(2+)ions.X-ray absorption fine structure(XAFS)spectroscopy revealed that the Mn atoms are preferentially located in the internal positions of the central belt while Ni and Co atoms preferentially reside in the external,solvent-accessible positions.Benefiting from the second substitution of catalytically active transition metals,the resulting{Mn_(2)Ni_(2)}and{Mn_(2)Co_(2)}can be utilized as Janus catalysts towards H_(2) evolution and O_(2) evolution under visible light irradiation with greatly-enhanced activity compared to that of parental{Mn_(2)Na_(2)}.The introduction of mixed transition metals into POM structures not only enriches the POMs family,but also provides an effective strategy to control electronic structures and catalytic properties of POM-based catalysts at the atomic level.展开更多
In terms of photoelectrochemical(PEC)hydrogen evolution,substantial challenge still remains regarding the controllable fabrication of quantum dots(QDs)-sensitized photocathodes with enhanced visible-light absorption,e...In terms of photoelectrochemical(PEC)hydrogen evolution,substantial challenge still remains regarding the controllable fabrication of quantum dots(QDs)-sensitized photocathodes with enhanced visible-light absorption,efficient charge carrier separation,and directional migration at the electrode interface.In this work,the CdTe/CdSe QDs-sensitized photocathodes were delicately constructed on p-type NiO-coated indium tin oxide(ITO)electrodes by spin-coating approach.The resulting co-sensitized photocathode exhibits a favorable pseudo-Type Ⅱ energetic band alignment that combines the advantages of strong light absorption of constituent QDs as well as the effective and oriented charge separation and migration.Upon green LED light illumination,the photogenerated electrons could be effectively transferred to a tetra-nickel-substituted polyoxometalate catalyst for hydrogen production while photogenerated holes will be scavenged at the NiO/ITO electrode.Under minimally optimized conditions,the pseudo-Type Ⅱ CdTe/CdSe-sensrtized photocathode yields a photcx:urrent density of over 100 pA/cm^(2) and a Faradaic efficiency of〜100%,which is among one of the most efficient QDs-based photocathode systems coupling with Ni-substituted polyoxometalate catalyst for photoelectrochemical hydrogen generation.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.21871025 and 21831001)the Recruitment Program of Global Experts(Young Talents)BIT Excellent Young Scholars Research Fund。
文摘The design and syntheses of metal-organic cages(MOCs)based on polyoxometalates(POMs)building blocks have attracted increasing attention due to their intriguing molecular architectures and physicochemical properties.In this work,we have successfully synthesized and systematically characterized a tetrahedral polyoxometalate-based organic cage(POC),K_(3)Na_(17)H_(12)[(C_(4)H_(6)O_(6))_(6)[Ni_(4)(OH)_(3)(A-α-SiW_(9)O_(34))]_(4)]·96H_(2)O(Ni_(16)L_(6)(SiW_(9))_(4)),using tritopic Ni_(4)-substituted Keggin cluster(Ni_(4)SiW_(9))as nodes and flexible L-(+)-tartaric acid ligands as linkers.The resulting POC tetrahedron has been firstly investigated as efficient catalyst for visible-light-driven hydrogen production,achieving a turnover number of 15,500 after 96-h photocatalysis.Such high catalytic performance of Ni_(16)L_(6)(SiW_(9))_(4)POC catalyst could be attributed to its unique cage structure,thereby offering more efficient catalytic component accessibility.In addition,spectroscopic analyses illustrated the photocatalytic mechanism and the structural stability of the TBA-Ni_(16)L_(6)(SiW_(9))_(4)catalyst during the photocatalytic process.
基金supported by the National Natural Science Foundation of China(21871025,21831001,21701168)the Recruitment Program of Global Experts(Young Talents)+1 种基金BIT Excellent Young Scholars Research Fundthe National Key R&D Program of China(2020YFA0406101)。
文摘The development of bifunctional catalysts for solar-driven hydrogen and oxygen evolution has been regarded as a challenging but interesting research topic.As promising multi-electron-transfer catalysts,previously reported polyoxometalate(POM)-based catalysts often contain only a single type of transition metal substitution for driving either hydrogen production or oxygen evolution.Herein,a viable two-step parental substitution approach has been developed to synthesize two structurally-new mixed-transition-metal-substituted polyoxometalates(mixed TMSPs),K_(6)Na_(4)[Mn_(2)Ni_(2)(H_(2)O)2(PW_(9)O_(34))2]·21H_(2)O({Mn_(2)Ni_(2)})and K10[Mn_(2)Co_(2)(H_(2)O)2(PW_(9)O_(34))2]·35H_(2)O({Mn_(2)Co_(2)}),using Na_(12)[Mn_(2)Na_(2)(PW_(9)O_(34))2]·36H_(2)O({Mn_(2)Na_(2)})as the precursor.Characterization results confirmed the nearly quantitative substitution of Na+with Ni_(2)+and Co_(2+)ions.X-ray absorption fine structure(XAFS)spectroscopy revealed that the Mn atoms are preferentially located in the internal positions of the central belt while Ni and Co atoms preferentially reside in the external,solvent-accessible positions.Benefiting from the second substitution of catalytically active transition metals,the resulting{Mn_(2)Ni_(2)}and{Mn_(2)Co_(2)}can be utilized as Janus catalysts towards H_(2) evolution and O_(2) evolution under visible light irradiation with greatly-enhanced activity compared to that of parental{Mn_(2)Na_(2)}.The introduction of mixed transition metals into POM structures not only enriches the POMs family,but also provides an effective strategy to control electronic structures and catalytic properties of POM-based catalysts at the atomic level.
基金support from the National Natural Science Foundation of China(Nos.21871025 and 21831001)the Recruitment Program of Global Experts(Young Talents)BIT Excellent Young Scholars Research Fund.
文摘In terms of photoelectrochemical(PEC)hydrogen evolution,substantial challenge still remains regarding the controllable fabrication of quantum dots(QDs)-sensitized photocathodes with enhanced visible-light absorption,efficient charge carrier separation,and directional migration at the electrode interface.In this work,the CdTe/CdSe QDs-sensitized photocathodes were delicately constructed on p-type NiO-coated indium tin oxide(ITO)electrodes by spin-coating approach.The resulting co-sensitized photocathode exhibits a favorable pseudo-Type Ⅱ energetic band alignment that combines the advantages of strong light absorption of constituent QDs as well as the effective and oriented charge separation and migration.Upon green LED light illumination,the photogenerated electrons could be effectively transferred to a tetra-nickel-substituted polyoxometalate catalyst for hydrogen production while photogenerated holes will be scavenged at the NiO/ITO electrode.Under minimally optimized conditions,the pseudo-Type Ⅱ CdTe/CdSe-sensrtized photocathode yields a photcx:urrent density of over 100 pA/cm^(2) and a Faradaic efficiency of〜100%,which is among one of the most efficient QDs-based photocathode systems coupling with Ni-substituted polyoxometalate catalyst for photoelectrochemical hydrogen generation.
