Six model compounds have been synthesized and used for probing the structural features of the Mn cluster in oxygen_evolving complex (OEC) of photosystem Ⅱ (PSⅡ). The model compounds contain Mn 2(μ_O) 2 and μ_O_...Six model compounds have been synthesized and used for probing the structural features of the Mn cluster in oxygen_evolving complex (OEC) of photosystem Ⅱ (PSⅡ). The model compounds contain Mn 2(μ_O) 2 and μ_O_μ_carboxylato di_manganese structural units, which offer Mn—Mn, Mn……Mn, and Mn—O(N) structural parameters consistent with the corresponding data of the OEC in PSⅡ, implying that the Mn cluster in OEC may possess similar structural features. Two model compounds containing halide anion have been used for discussing the binding of Cl - to Mn in PSⅡ. It is suggested that in the five S states, ligand exchange would lead to the ligation of chloride to Mn in the S states with Mn of higher valence.展开更多
Material strain and reconstruction effects are critical for catalysis reactions,but current insights into operando strain effects during reaction and means to master catalyst reconstruction are still lacking.Here,we p...Material strain and reconstruction effects are critical for catalysis reactions,but current insights into operando strain effects during reaction and means to master catalyst reconstruction are still lacking.Here,we propose a facile thermal-induced phase-segregation strategy to simultaneously master material operando strain and reconstruction effects for enhanced oxygen-evolving reaction(OER).Specifically,self-assembled and controllable layered LiCoO_(2)phase and Co_(3)O_(4)spinel can be generated from pristine Li2Co_(2)O_(4)spinel via Li and O volatilization under different temperatures,realizing controllable proportions of two phases by calcination temperature.Combined operando and ex-situ characterizations reveal that obvious tensile strain along(003)plane appears on layered LixCoO_(2)phase during OER,while low-valence Co_(3)O_(4)phase transforms into high-valence CoOOHx,realizing simultaneous operando strain and reconstruction effects.Further experimental and computational investigations demonstrate that both strained LixCoO_(2)phase and reconstructed CoOOHxcompound contribute to the beneficial adsorption of important OH-reactants,while respective roles in activity and stability are uncovered by exploring their latticeoxygen participation mechanism.This work not only reveals material operando strain effects during OER,but also inaugurates a new thermal-induced phase-segregation strategy to artificially master material operando strain and reconstruction effects,which will enlighten rational material design for many potential reactions and applications.展开更多
So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is p...So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of 'C' shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxi-展开更多
Oxygen-evolving complex （OEC） protein is the original name for membrane-peripheral subunits of photosystem （PS） II. Recently, multiple isoforms and homologs for OEC proteins have been iden- tified in the chloropla...Oxygen-evolving complex （OEC） protein is the original name for membrane-peripheral subunits of photosystem （PS） II. Recently, multiple isoforms and homologs for OEC proteins have been iden- tified in the chloroplast thylakoid lumen, indicating that functional diversification has occurred in the OEC family. Gene expression profiles suggest that the Arabidopsis OEC proteins are roughly categorized into three groups： the authentic OEC group, the stressresponsive group, and the group including proteins related to the chloroplast NAD（P）H dehydrogenase （NDH） complex involved in cyclic electron transport around PSI. Based on the above gene expression profiles, molecular functions of the OEC family proteins are discussed together with our current knowledge about their functions.展开更多
The understanding of the structure-function relationship of the oxygen-evolving center(OEC), a Mn_4 Cacluster, in photosystem II is impeded mainly due to the complexity of the protein environment and lack of rational ...The understanding of the structure-function relationship of the oxygen-evolving center(OEC), a Mn_4 Cacluster, in photosystem II is impeded mainly due to the complexity of the protein environment and lack of rational chemical models as a reference. In this study, two novel Mn_4-oxido complexes have been synthesized and characterized, in which the peripheral ligands of the [Mn_4~Ⅲ] core are provided by eight μ_2-carboxylate groups and two neutral terminal ligands(pyridine or isoquinoline). This type of peripheral ligation is very similar to the Mn_4Ca-oxide model complexes recently reported to mimic the OEC. The new Mn_4-oxide complex can catalyze the oxygen-evolving reaction in the presence of Bu^tOOH as an oxidant. The structure and redox properties comparison of the Mn_4-oxido and Mn_4Ca-oxido complexes provide important clues to understanding the functional role of Ca in the OEC in natural photosynthesis, and develop more efficient artificial catalysts for the water-splitting reaction in the future.展开更多
The interaction between the Mn-cluster and its peripheral ligands in oxygen-evolving center is still unclear. Theoretical investigation on the coordination of histidine, H2O, and Cl to Mn2O2 units in OEC is conducted....The interaction between the Mn-cluster and its peripheral ligands in oxygen-evolving center is still unclear. Theoretical investigation on the coordination of histidine, H2O, and Cl to Mn2O2 units in OEC is conducted. The following conclusions are obtained: (i) both histidine and H2O molecule, bound to the two Mn ions, respectively, are vertical to the Mn2O2 plane, and maintain a large distance; (ii) the two H2O molecules cannot bind to the same Mn2O2 unit. Based on Mn-cluster structure in OEC, we theoretically predict that two H2O molecules bind to the two Mn ions at the "C"-shaped open end in S0 state, while two His residues at the closed end. Cl ion can only terminally ligate at the open end. Individual valence for the four Mn ions in S0 state is assigned.展开更多
Non-noble metal catalysts are suitable for the oxygen evolution reaction(OER)owing to their original oxidation states and oxygen coordination environments,which can regulate the adsorption of OH−at the active sites to...Non-noble metal catalysts are suitable for the oxygen evolution reaction(OER)owing to their original oxidation states and oxygen coordination environments,which can regulate the adsorption of OH−at the active sites to facilitate the formation of oxygencontaining intermediates.However,the difficulties encountered in the conversion of intermediates(M–OH,M–O,and M–OOH)lead to low efficiency.Decorations of transition metal catalysts with foreign elements are regarded effective solutions,among which decoration with Ce-based materials(CeBM)is the most prominent.This review investigates the current status and future prospects of CeBM-decorated transition metal electrocatalysts.By presenting a thorough account of the latest development,we aim to set a common ground for the research community for a deeper understanding of the roles of CeBM that originate from its unique electronic structure and abundant oxygen vacancies.Moreover,we wish to provide our own perspectives as to how to further the design of Ce-based OER electrocatalysts and where such catalysts may be applied in fields beyond electrocatalysis.展开更多
The ettect of anionic phosphatidylglycerol (HG) on oxygen evolution in a photosystem Ⅱ (PS Ⅱ) particle depleted of Ca2+ (designated dCaPS Ⅱ) has been investigated. The major finding is the observation of a new role...The ettect of anionic phosphatidylglycerol (HG) on oxygen evolution in a photosystem Ⅱ (PS Ⅱ) particle depleted of Ca2+ (designated dCaPS Ⅱ) has been investigated. The major finding is the observation of a new role of PG in the PS Ⅱ function. That is, PG restores nearly the lost oxygen evolution in dCaPS Ⅱ particle owing to Ca2+ depletion to the levels in intact PS Ⅱ . Furthermore, there is a stimulation of oxygen-evolving activity in the dCaPSⅡ complexed with PG in the presence of exogenous CaCI2, which PG enhances increasingly oxygen evolution with increasing CaCI2 concentration. It is suggested that PG-induced oxygen evolution recovery of dCa PS Ⅱresumption of normal structure in protein by PG effect, whereas the enhancement of oxygen evolution in complex subject to CaCI2 is ascribed to the optimization of such a structure due to coordination complex formation of Ca2+ ions with PG.展开更多
The anodic behaviour of pre-oxidised and non-oxidised Cu-Al-based anodes(Cu-10Al and Cu-9.8Al-2Mn)in KF-AlF_(3)-Al_(2)O_(3)melts was studied through galvanostatic and potentiodynamic polarization techniques.The alloy ...The anodic behaviour of pre-oxidised and non-oxidised Cu-Al-based anodes(Cu-10Al and Cu-9.8Al-2Mn)in KF-AlF_(3)-Al_(2)O_(3)melts was studied through galvanostatic and potentiodynamic polarization techniques.The alloy compositions were oxidised for a short-term(8 h)at 700℃,followed by galvanostatic polarization for 1 h at 800℃with an applied current density of 0.4 A/cm^(2).The potentiodynamic curves were recorded with a sweep rate of 0.01 V/s.XRD analysis was conducted on frozen melt samples collected on the surface of the anode,and SEM observation was performed on the anode after the experiment to study the phases of the scales formed on the alloys.All the anode materials had a steady potential between 2.30 and 2.50 V(vs Al/AlF_(3)).The corrosion rates of the anodes were calculated from the data acquired through potentiodynamic polarization.It was seen that pre-oxidised anodes possess a low corrosion rate compared to those without pre-oxidation treatment.展开更多
Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands...Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates.In this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional calculations.Structural rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 species.Possible alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are discussed.These findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.展开更多
The composite photoanodes composed by cobalt phosphate catalyst(Co-Pi) modified semiconductor have been widely used for solar water splitting,but the improvement mechanism has not been experimentally confirmed.Here we...The composite photoanodes composed by cobalt phosphate catalyst(Co-Pi) modified semiconductor have been widely used for solar water splitting,but the improvement mechanism has not been experimentally confirmed.Here we use transient photoelectrochemical measurements and impedance spectroscopy to investigate the effect of Co-Pi catalyst on hematite nanowire photoanode.It is found that under illumination the Co-Pi catalyst can efficiently promote the transfer of photo-generated holes to the Co-Pi layer by increasing the electrical conductivity of the composite structure under a low potential.The Co-Pi catalyst can recombine with photo-generated electrons to reduce the surface recombination efficiency of photo-generated holes and electrons under a high potential.These results provide important new understanding of the performance improvement mechanism for the Co-Pi-modified semiconductor nanowire composite photoanodes.展开更多
Manganese （Mn） is an essential catalytic metal in the Mn-cluster that oxidizes water to produce oxygen dur- ing photosynthesis. However, the transport protein（s） responsible for Mn2＋ import into the chloroplast r...Manganese （Mn） is an essential catalytic metal in the Mn-cluster that oxidizes water to produce oxygen dur- ing photosynthesis. However, the transport protein（s） responsible for Mn2＋ import into the chloroplast re- mains unknown. Here, we report the characterization ofArabidopsis CMT1 （Chloroplast Manganese Trans- porter 1）, an evolutionarily conserved protein in the Uncharacterized Protein Family 0016 （UPFO016）, that is required for manganese accumulation into the chloroplast. CMT1 is expressed primarily in green tissues, and its encoded product is localized in the inner envelope membrane of the chloroplast. Disruption of CMT1 in the T-DNA insertional mutant cmtl-1 resulted in stunted plant growth, defective thylakoid stacking, and severe reduction of photosystem II complexes and photosynthetic activity. Consistent with reduced oxy- gen evolution capacity, the mutant chloroplasts contained less manganese than the wild-type ones. In sup- port of its function as a Mn transporter, CMT1 protein supported the growth and enabled Mn2＋ accumula- tion in the yeast cells of Mn2＋-uptake deficient mutant （3smfl）. Taken together, our results indicate that CMT1 functions as an inner envelope Mn transporter responsible for chloroplast Mn2＋ uptake.展开更多
基金The State Key Basic Research and Development Plan(G1998010100)the National Natural Science Foundation of China(29733090,29973047,39970177)
文摘Six model compounds have been synthesized and used for probing the structural features of the Mn cluster in oxygen_evolving complex (OEC) of photosystem Ⅱ (PSⅡ). The model compounds contain Mn 2(μ_O) 2 and μ_O_μ_carboxylato di_manganese structural units, which offer Mn—Mn, Mn……Mn, and Mn—O(N) structural parameters consistent with the corresponding data of the OEC in PSⅡ, implying that the Mn cluster in OEC may possess similar structural features. Two model compounds containing halide anion have been used for discussing the binding of Cl - to Mn in PSⅡ. It is suggested that in the five S states, ligand exchange would lead to the ligation of chloride to Mn in the S states with Mn of higher valence.
基金funded by the Australian Research Council Discovery Projects(DP160104835,Z.Shao)the Guangdong Basic and Applied Basic Research Foundation(2023A1515012878,D.Guan)+1 种基金the PolyU Distinguished Postdoctoral Fellowship Scheme(1-YWBU,D.Guan)the support from the Max Planck-POSTECH-Hsinchu Center for Complex Phase Materials。
文摘Material strain and reconstruction effects are critical for catalysis reactions,but current insights into operando strain effects during reaction and means to master catalyst reconstruction are still lacking.Here,we propose a facile thermal-induced phase-segregation strategy to simultaneously master material operando strain and reconstruction effects for enhanced oxygen-evolving reaction(OER).Specifically,self-assembled and controllable layered LiCoO_(2)phase and Co_(3)O_(4)spinel can be generated from pristine Li2Co_(2)O_(4)spinel via Li and O volatilization under different temperatures,realizing controllable proportions of two phases by calcination temperature.Combined operando and ex-situ characterizations reveal that obvious tensile strain along(003)plane appears on layered LixCoO_(2)phase during OER,while low-valence Co_(3)O_(4)phase transforms into high-valence CoOOHx,realizing simultaneous operando strain and reconstruction effects.Further experimental and computational investigations demonstrate that both strained LixCoO_(2)phase and reconstructed CoOOHxcompound contribute to the beneficial adsorption of important OH-reactants,while respective roles in activity and stability are uncovered by exploring their latticeoxygen participation mechanism.This work not only reveals material operando strain effects during OER,but also inaugurates a new thermal-induced phase-segregation strategy to artificially master material operando strain and reconstruction effects,which will enlighten rational material design for many potential reactions and applications.
文摘So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of 'C' shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxi-
基金supported by a Grant-in Aid for Scientific Research on Priority Areas(grant no.17051016 to K.I.and F.S.)for Young Scientists(B)(grant no.18770032to K.I.)
文摘Oxygen-evolving complex （OEC） protein is the original name for membrane-peripheral subunits of photosystem （PS） II. Recently, multiple isoforms and homologs for OEC proteins have been iden- tified in the chloroplast thylakoid lumen, indicating that functional diversification has occurred in the OEC family. Gene expression profiles suggest that the Arabidopsis OEC proteins are roughly categorized into three groups： the authentic OEC group, the stressresponsive group, and the group including proteins related to the chloroplast NAD（P）H dehydrogenase （NDH） complex involved in cyclic electron transport around PSI. Based on the above gene expression profiles, molecular functions of the OEC family proteins are discussed together with our current knowledge about their functions.
基金supported by the National Natural Science Foundation of China (20973186,31070216,21076049,and 91427303)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17030600)
文摘The understanding of the structure-function relationship of the oxygen-evolving center(OEC), a Mn_4 Cacluster, in photosystem II is impeded mainly due to the complexity of the protein environment and lack of rational chemical models as a reference. In this study, two novel Mn_4-oxido complexes have been synthesized and characterized, in which the peripheral ligands of the [Mn_4~Ⅲ] core are provided by eight μ_2-carboxylate groups and two neutral terminal ligands(pyridine or isoquinoline). This type of peripheral ligation is very similar to the Mn_4Ca-oxide model complexes recently reported to mimic the OEC. The new Mn_4-oxide complex can catalyze the oxygen-evolving reaction in the presence of Bu^tOOH as an oxidant. The structure and redox properties comparison of the Mn_4-oxido and Mn_4Ca-oxido complexes provide important clues to understanding the functional role of Ca in the OEC in natural photosynthesis, and develop more efficient artificial catalysts for the water-splitting reaction in the future.
文摘The interaction between the Mn-cluster and its peripheral ligands in oxygen-evolving center is still unclear. Theoretical investigation on the coordination of histidine, H2O, and Cl to Mn2O2 units in OEC is conducted. The following conclusions are obtained: (i) both histidine and H2O molecule, bound to the two Mn ions, respectively, are vertical to the Mn2O2 plane, and maintain a large distance; (ii) the two H2O molecules cannot bind to the same Mn2O2 unit. Based on Mn-cluster structure in OEC, we theoretically predict that two H2O molecules bind to the two Mn ions at the "C"-shaped open end in S0 state, while two His residues at the closed end. Cl ion can only terminally ligate at the open end. Individual valence for the four Mn ions in S0 state is assigned.
基金This research was made possible as a result of a generous grant from Shenzhen Nobel Prize Scientists Laboratory Project(grant no.C17213101)Guangdong Provincial Key Laboratory of Catalysis(no.2020B121201002)+1 种基金Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(no.2018B030322001)China Postdoctoral Science Foundation(no.2018M642133).
文摘Non-noble metal catalysts are suitable for the oxygen evolution reaction(OER)owing to their original oxidation states and oxygen coordination environments,which can regulate the adsorption of OH−at the active sites to facilitate the formation of oxygencontaining intermediates.However,the difficulties encountered in the conversion of intermediates(M–OH,M–O,and M–OOH)lead to low efficiency.Decorations of transition metal catalysts with foreign elements are regarded effective solutions,among which decoration with Ce-based materials(CeBM)is the most prominent.This review investigates the current status and future prospects of CeBM-decorated transition metal electrocatalysts.By presenting a thorough account of the latest development,we aim to set a common ground for the research community for a deeper understanding of the roles of CeBM that originate from its unique electronic structure and abundant oxygen vacancies.Moreover,we wish to provide our own perspectives as to how to further the design of Ce-based OER electrocatalysts and where such catalysts may be applied in fields beyond electrocatalysis.
文摘The ettect of anionic phosphatidylglycerol (HG) on oxygen evolution in a photosystem Ⅱ (PS Ⅱ) particle depleted of Ca2+ (designated dCaPS Ⅱ) has been investigated. The major finding is the observation of a new role of PG in the PS Ⅱ function. That is, PG restores nearly the lost oxygen evolution in dCaPS Ⅱ particle owing to Ca2+ depletion to the levels in intact PS Ⅱ . Furthermore, there is a stimulation of oxygen-evolving activity in the dCaPSⅡ complexed with PG in the presence of exogenous CaCI2, which PG enhances increasingly oxygen evolution with increasing CaCI2 concentration. It is suggested that PG-induced oxygen evolution recovery of dCa PS Ⅱresumption of normal structure in protein by PG effect, whereas the enhancement of oxygen evolution in complex subject to CaCI2 is ascribed to the optimization of such a structure due to coordination complex formation of Ca2+ ions with PG.
文摘The anodic behaviour of pre-oxidised and non-oxidised Cu-Al-based anodes(Cu-10Al and Cu-9.8Al-2Mn)in KF-AlF_(3)-Al_(2)O_(3)melts was studied through galvanostatic and potentiodynamic polarization techniques.The alloy compositions were oxidised for a short-term(8 h)at 700℃,followed by galvanostatic polarization for 1 h at 800℃with an applied current density of 0.4 A/cm^(2).The potentiodynamic curves were recorded with a sweep rate of 0.01 V/s.XRD analysis was conducted on frozen melt samples collected on the surface of the anode,and SEM observation was performed on the anode after the experiment to study the phases of the scales formed on the alloys.All the anode materials had a steady potential between 2.30 and 2.50 V(vs Al/AlF_(3)).The corrosion rates of the anodes were calculated from the data acquired through potentiodynamic polarization.It was seen that pre-oxidised anodes possess a low corrosion rate compared to those without pre-oxidation treatment.
基金financial support of this work by the Swedish Research Council(2017-00935)Swedish Energy Agency and Knut and Alice Wallenberg Foundation(KAW 2016.0072)。
文摘Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates.In this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional calculations.Structural rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 species.Possible alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are discussed.These findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.
基金financially supported by the National Natural Science Foundation of China (No.21503109)the Research-Starting Funds for Introduced Talents of Nanjing Tech University。
文摘The composite photoanodes composed by cobalt phosphate catalyst(Co-Pi) modified semiconductor have been widely used for solar water splitting,but the improvement mechanism has not been experimentally confirmed.Here we use transient photoelectrochemical measurements and impedance spectroscopy to investigate the effect of Co-Pi catalyst on hematite nanowire photoanode.It is found that under illumination the Co-Pi catalyst can efficiently promote the transfer of photo-generated holes to the Co-Pi layer by increasing the electrical conductivity of the composite structure under a low potential.The Co-Pi catalyst can recombine with photo-generated electrons to reduce the surface recombination efficiency of photo-generated holes and electrons under a high potential.These results provide important new understanding of the performance improvement mechanism for the Co-Pi-modified semiconductor nanowire composite photoanodes.
文摘Manganese （Mn） is an essential catalytic metal in the Mn-cluster that oxidizes water to produce oxygen dur- ing photosynthesis. However, the transport protein（s） responsible for Mn2＋ import into the chloroplast re- mains unknown. Here, we report the characterization ofArabidopsis CMT1 （Chloroplast Manganese Trans- porter 1）, an evolutionarily conserved protein in the Uncharacterized Protein Family 0016 （UPFO016）, that is required for manganese accumulation into the chloroplast. CMT1 is expressed primarily in green tissues, and its encoded product is localized in the inner envelope membrane of the chloroplast. Disruption of CMT1 in the T-DNA insertional mutant cmtl-1 resulted in stunted plant growth, defective thylakoid stacking, and severe reduction of photosystem II complexes and photosynthetic activity. Consistent with reduced oxy- gen evolution capacity, the mutant chloroplasts contained less manganese than the wild-type ones. In sup- port of its function as a Mn transporter, CMT1 protein supported the growth and enabled Mn2＋ accumula- tion in the yeast cells of Mn2＋-uptake deficient mutant （3smfl）. Taken together, our results indicate that CMT1 functions as an inner envelope Mn transporter responsible for chloroplast Mn2＋ uptake.
