Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, s...Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure spectroscopy, and its performances for removal of Pb^2＋ and Cr^3＋ from aqueous solutions were investigated. Co doping has a negligible effect on the structure and morphology of cryptomelane but increases the specific surface area and Mn average oxidation state. Mn and Co K-edge extended X-ray absorption fine structure spectroscopy（EXAFS） analysis shows that Co barely affects the atomic coordination environments of Mn, and distances of edge- and corner-sharing Co–Me（Me_Co, Mn） pairs are shorter than those of the corresponding Mn–Me pairs, implying the replacement of framework Mn（III） by Co（III）. These Co-doped cryptomelanes can quickly oxidize Cr3＋to be HCr O4-and remove 45%–66% of the total Cr in the reaction systems by adsorption and fixation, and they have enhanced Pb2＋adsorption capacities. Thus these materials are promising adsorbents for heavy metal remediation. The results demonstrate the design and modification of environmental friendly Mn oxide materials and can help us understand the interaction mechanisms of transition metals with Mn oxides.展开更多
n-Type polycrystalline SnSe with Ti,Pb co-doping was synthesized by combining mechanical alloying(MA)with spark plasma sintering(SPS).It is revealed that Ti is an effective cationic dopant to convert SnSe from a p-typ...n-Type polycrystalline SnSe with Ti,Pb co-doping was synthesized by combining mechanical alloying(MA)with spark plasma sintering(SPS).It is revealed that Ti is an effective cationic dopant to convert SnSe from a p-type to an n-type semiconductor,and the thermoelectric performance of the Ti-doped SnSe is also improved in comparison with the pristine sample due to an enhanced power factor.Furthermore,after further Pb doping,an obviously improved electrical conductivity together with a moderate Seebeck coefficient can be achieved,which results in an improvement of the power factor with a maximum value of 300μW m^(−1) K^(−2) at 773 K.Meanwhile,the lattice thermal conductivity is significantly reduced because of the enhanced phonon scattering owing to the mass and strain fluctuations.Therefore,a final ZT value of 0.4 was obtained for composition of Sn_(0.74)Pb_(0.20)Ti_(0.06)Se at 773 K,which is a conservative value for n-type SnSe with cationic dopant prepared by the simple preparation process of MA and SPS.展开更多
The recent claim of potential room-temperature superconductivity in Pb_(10−x)Cu_(x)(PO_(4))_(6)O has attracted widespread attention.However,the signature of superconductivity is later attributed to the Cu_(2)S impurit...The recent claim of potential room-temperature superconductivity in Pb_(10−x)Cu_(x)(PO_(4))_(6)O has attracted widespread attention.However,the signature of superconductivity is later attributed to the Cu_(2)S impurity formed during the multiple-step synthesis procedure.Here we report a simple one-step approach for synthesizing single-phase chloride analogue Cu-doped Pb10(PO_(4))_(6)Cl_(2) using PbO,PbCl_(2),CuCl_(2),and NH_(4)H_(2)PO_(4) as starting materials.Irrespective of the initial stoichiometry,Cu doping always leads to a lattice expansion in Pb10(PO_(4))_(6)Cl_(2).This indicates that Cu prefers to reside in the hexagonal channels rather than as substitutes at the Pb sites,and the chemical formula is expressed as Pb10(PO_(4))_(6)Cu_(x)Cl_(2).All the Pb10(PO_(4))_(6)Cu_(x)Cl_(2)(0≤x≤1.0)samples are found to be semiconductors with wide band gaps of 4.46–4.59 eV,and the Cu-doped ones(x=0.5 and 1.0)exhibit a paramagnetic behavior without any phase transition between 400 and 1.8 K.Our study calls for a reinvestigation of the Cu location in Pb_(10−x)Cu_(x)(PO_(4))_(6)O and supports the absence of superconductivity in this oxyapatite.展开更多
Seawater electrolysis holds great promise for sustainable green hydrogen production,but it is challenged by chloride-induced corrosion.Herein,we demonstrate the hydrothermal preparation of Pb-doped NiFe layered double...Seawater electrolysis holds great promise for sustainable green hydrogen production,but it is challenged by chloride-induced corrosion.Herein,we demonstrate the hydrothermal preparation of Pb-doped NiFe layered double hydroxide on Ni foam(Pb-NiFe LDH/NF)for alkaline seawater oxidation electrocatalysis.Our Pb-NiFe LDH/NF requires a low overpotential of only 381 mV to attain a current density of 1000 mA·cm^(-2),superior to its NiFe LDH/NF counterpart(423 mV).Additionally,it operates continuously for 1000 h with negligible performance degradation and minimal active chlorine production.In situ Raman spectroscopy analysis reveals that Pb incorporation facilitates catalyst surface reconstruction,thereby enhancing oxygen evolution reaction activity.Importantly,Pb selectively adsorbs free Cl^(-)to form stable Pb-Cl species under the influence of an applied electric field.This process creates a Cl^(-)-free layer near the anode surface,thereby enhancing the catalyst’s chlorine corrosion resistance.展开更多
Widespread deployment of proton exchange membrane water electrolyzers(PEMWE)relies on acid-stable oxygen evolution reaction(OER)catalysts capable of operating at high current densities.Inspired by the robust chemistry...Widespread deployment of proton exchange membrane water electrolyzers(PEMWE)relies on acid-stable oxygen evolution reaction(OER)catalysts capable of operating at high current densities.Inspired by the robust chemistry of lead-acid batteries,we introduce lead(Pb)into ruthenium-iridium mixed oxide(RuIrO_(x))through a facile sol-gel method.The as-prepared RuIrPbO_(x)nanoparticulate catalysts with the optimal composition(Ru_(0.5)Ir_(0.4)Pb_(0.1)O_(x))achieve an overpotential of 241 mV at 10 mA cm^(-2)and exceptional stability of 1000 h at a high current density of 100 mA cm^(-2)without degradation.In situ differential electrochemical mass spectrometry indicates that doping RuIrO_(x)with an appropriate amount of Pb helps to suppress the participation of lattice oxygen during OER,contributing to structural preservation and long-term stability.Density functional theory calculations reveal that Pb doping effectively regulates the electronic structure of the Ru sites,reducing Ru-O covalency,which in turn increases the Ru dissolution energy and therefore prevents Ru leaching—a key degradation pathway for Ru-containing OER catalysts.When integrated into a membrane electrode assembly,the PEMWE cell can operate at a large current density of 3.0 A cm^(-2)under 1.96 V(at 60℃)for 400 h with minimal performance degradation,demonstrating the significant potential of the Ru_(0.5)Ir_(0.4)Pb_(0.1)O_(x)as an efficient and durable OER catalyst for practical applications under demanding conditions.展开更多
基金supported by the National Natural Science Foundation of China (Nos.41271253 and 41401250)the Huazhong Agricultural University Doctoral Start-up Fund (Grant 52902-0900206162)
文摘Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure spectroscopy, and its performances for removal of Pb^2＋ and Cr^3＋ from aqueous solutions were investigated. Co doping has a negligible effect on the structure and morphology of cryptomelane but increases the specific surface area and Mn average oxidation state. Mn and Co K-edge extended X-ray absorption fine structure spectroscopy（EXAFS） analysis shows that Co barely affects the atomic coordination environments of Mn, and distances of edge- and corner-sharing Co–Me（Me_Co, Mn） pairs are shorter than those of the corresponding Mn–Me pairs, implying the replacement of framework Mn（III） by Co（III）. These Co-doped cryptomelanes can quickly oxidize Cr3＋to be HCr O4-and remove 45%–66% of the total Cr in the reaction systems by adsorption and fixation, and they have enhanced Pb2＋adsorption capacities. Thus these materials are promising adsorbents for heavy metal remediation. The results demonstrate the design and modification of environmental friendly Mn oxide materials and can help us understand the interaction mechanisms of transition metals with Mn oxides.
基金supported by the National Nature Science Foundation(grant no.51302140)Shenzhen Science and Technology Plan Project(no.JCYJ20160422102622085,JCYJ20150827165038323)the Natural Science Foundation of SZU(no.2016016).
文摘n-Type polycrystalline SnSe with Ti,Pb co-doping was synthesized by combining mechanical alloying(MA)with spark plasma sintering(SPS).It is revealed that Ti is an effective cationic dopant to convert SnSe from a p-type to an n-type semiconductor,and the thermoelectric performance of the Ti-doped SnSe is also improved in comparison with the pristine sample due to an enhanced power factor.Furthermore,after further Pb doping,an obviously improved electrical conductivity together with a moderate Seebeck coefficient can be achieved,which results in an improvement of the power factor with a maximum value of 300μW m^(−1) K^(−2) at 773 K.Meanwhile,the lattice thermal conductivity is significantly reduced because of the enhanced phonon scattering owing to the mass and strain fluctuations.Therefore,a final ZT value of 0.4 was obtained for composition of Sn_(0.74)Pb_(0.20)Ti_(0.06)Se at 773 K,which is a conservative value for n-type SnSe with cationic dopant prepared by the simple preparation process of MA and SPS.
基金support from the Foundation of Westlake University,Prof.
文摘The recent claim of potential room-temperature superconductivity in Pb_(10−x)Cu_(x)(PO_(4))_(6)O has attracted widespread attention.However,the signature of superconductivity is later attributed to the Cu_(2)S impurity formed during the multiple-step synthesis procedure.Here we report a simple one-step approach for synthesizing single-phase chloride analogue Cu-doped Pb10(PO_(4))_(6)Cl_(2) using PbO,PbCl_(2),CuCl_(2),and NH_(4)H_(2)PO_(4) as starting materials.Irrespective of the initial stoichiometry,Cu doping always leads to a lattice expansion in Pb10(PO_(4))_(6)Cl_(2).This indicates that Cu prefers to reside in the hexagonal channels rather than as substitutes at the Pb sites,and the chemical formula is expressed as Pb10(PO_(4))_(6)Cu_(x)Cl_(2).All the Pb10(PO_(4))_(6)Cu_(x)Cl_(2)(0≤x≤1.0)samples are found to be semiconductors with wide band gaps of 4.46–4.59 eV,and the Cu-doped ones(x=0.5 and 1.0)exhibit a paramagnetic behavior without any phase transition between 400 and 1.8 K.Our study calls for a reinvestigation of the Cu location in Pb_(10−x)Cu_(x)(PO_(4))_(6)O and supports the absence of superconductivity in this oxyapatite.
基金funding this work through Large Research Project under Grant(No.RGP2/28/46).
文摘Seawater electrolysis holds great promise for sustainable green hydrogen production,but it is challenged by chloride-induced corrosion.Herein,we demonstrate the hydrothermal preparation of Pb-doped NiFe layered double hydroxide on Ni foam(Pb-NiFe LDH/NF)for alkaline seawater oxidation electrocatalysis.Our Pb-NiFe LDH/NF requires a low overpotential of only 381 mV to attain a current density of 1000 mA·cm^(-2),superior to its NiFe LDH/NF counterpart(423 mV).Additionally,it operates continuously for 1000 h with negligible performance degradation and minimal active chlorine production.In situ Raman spectroscopy analysis reveals that Pb incorporation facilitates catalyst surface reconstruction,thereby enhancing oxygen evolution reaction activity.Importantly,Pb selectively adsorbs free Cl^(-)to form stable Pb-Cl species under the influence of an applied electric field.This process creates a Cl^(-)-free layer near the anode surface,thereby enhancing the catalyst’s chlorine corrosion resistance.
基金support from the Ministry of Science and Technology of China through the National Key R&D Program(Grant No.2024YFE0114900)the Talent Recruitment Program(Grant No.22J4021Z311)as well as from Songshan Lake Materials Laboratory through the startup grant(Grant No.Y2D1051Z311).
文摘Widespread deployment of proton exchange membrane water electrolyzers(PEMWE)relies on acid-stable oxygen evolution reaction(OER)catalysts capable of operating at high current densities.Inspired by the robust chemistry of lead-acid batteries,we introduce lead(Pb)into ruthenium-iridium mixed oxide(RuIrO_(x))through a facile sol-gel method.The as-prepared RuIrPbO_(x)nanoparticulate catalysts with the optimal composition(Ru_(0.5)Ir_(0.4)Pb_(0.1)O_(x))achieve an overpotential of 241 mV at 10 mA cm^(-2)and exceptional stability of 1000 h at a high current density of 100 mA cm^(-2)without degradation.In situ differential electrochemical mass spectrometry indicates that doping RuIrO_(x)with an appropriate amount of Pb helps to suppress the participation of lattice oxygen during OER,contributing to structural preservation and long-term stability.Density functional theory calculations reveal that Pb doping effectively regulates the electronic structure of the Ru sites,reducing Ru-O covalency,which in turn increases the Ru dissolution energy and therefore prevents Ru leaching—a key degradation pathway for Ru-containing OER catalysts.When integrated into a membrane electrode assembly,the PEMWE cell can operate at a large current density of 3.0 A cm^(-2)under 1.96 V(at 60℃)for 400 h with minimal performance degradation,demonstrating the significant potential of the Ru_(0.5)Ir_(0.4)Pb_(0.1)O_(x)as an efficient and durable OER catalyst for practical applications under demanding conditions.
