Electrocatalytic dehalogenation has emerged as a sustainable technology for environmental remediation.However,efficient electrocatalysts are still lacking,especially for wastewater treatment.In this study,a Pd/γ-MnO_...Electrocatalytic dehalogenation has emerged as a sustainable technology for environmental remediation.However,efficient electrocatalysts are still lacking,especially for wastewater treatment.In this study,a Pd/γ-MnO2/Ni foam composite electrode was designed.The introduction of hexagonal flake-likeγ-MnO2successfully prevented Pd aggregation and optimized electrode structure.Compared to previously reported electrodes,Pd/γ-MnO2/Ni foam composite electrode had lower Pd loading and higher dehalogenation efficiency and current efficiency.In 2-chlorophenol(2-CP)solution and dye wastewater,over 99%dehalogenation efficiencies were achieved within 120 min(10 mA),without adjusting the pH value.Computational results suggested thatγ-MnO2can promote the adsorption of H2O,which is the key rate-limiting step for 2-CP hydrodechlorination.In addition,γMnO2facilitated water dissociation and served as an intermediary for transferring atomic hydrogen(H∗)from Pd to Ni foam.This hydrogen spillover mechanism extended the reactive area of electrode,hindered H2evolution and enhanced the dehalogenation efficiency.It was found that Pd/γ-MnO2/Ni foam electrode showed excellent dehalogenation performance under both acidic and neutral conditions,and exhibited good resistance to the coexisting ions(such as Cl−,NO3−and HCO 3−).Hence,the Pd/γ-MnO2/Ni foam electrode demonstrates strong potential for the treatment of high-salinity wastewater.The high dehalogenation efficiency and long service life of Pd/γ-MnO2/Ni foam electrode in dye wastewater confirmed its feasibility and applicability.This study explored the synthesis and interfacial mechanism of electrodes,paving the way for efficient remediation of halogenated organic pollutants in wastewater.展开更多
Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique...Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy(EDXS), anode polarization curves, quasi-stationary polarization(Tafel) curves, electrochemical impedance spectroscopy(EIS), scanning electron microscopy(SEM), and X-ray diffraction(XRD). Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential(0.610 V at 500 A/m2) for oxygen evolution, the best electrocatalytic activity, the longest service life(360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2), and the lowest cell voltage(2.75 V at 500 A/m2). Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.展开更多
Aqueous Zn//MnO2 batteries are emerging as promising large-scale energy storage devices owing to their cost-effectiveness,high safety,high output voltage,and energy density.However,the MnO2 cathode suffers from intrin...Aqueous Zn//MnO2 batteries are emerging as promising large-scale energy storage devices owing to their cost-effectiveness,high safety,high output voltage,and energy density.However,the MnO2 cathode suffers from intrinsically poor rate performance and rapid capacity deterioration.Here,we remove the roadblock by compositing MnO2 nanorods with highly conductive graphene,which remarkably enhances the electrochemical properties of the MnO2 cathode.Benefiting from the boosted electric conductivity and ion diffusion rate as well as the structural protection of graphene,the Zn//MnO2-graphene battery presents an admirable capacity of 301 mAh g^-1 at 0.5 A g^-1,corresponding to a high energy density of 411.6 Wh kg^-1.Even at a high current density of 10 A g^-1,a decent capacity of 95.8 mAh g^-1 is still obtained,manifesting its excellent rate property.Furthermore,an impressive power density of 15 kW kg^-1 is achieved by the Zn//MnO2-graphene battery.展开更多
Al/α-PbO2/β-PbO2 composite electrodes doped with rare earth oxide (CeO2) were prepared by anodic oxidation method investigate the influence of nano-CeO2 dopants on the properties of Al/α-PbO2/β-PbO2-CeO2 electro...Al/α-PbO2/β-PbO2 composite electrodes doped with rare earth oxide (CeO2) were prepared by anodic oxidation method investigate the influence of nano-CeO2 dopants on the properties of Al/α-PbO2/β-PbO2-CeO2 electrodes and the impact of α-PbO2 as the intermediate layer. The results show that using α-PbO2 as the intermediate layer will benefit the crystallization of β-PbO2 and β-PbO2 is more suitable as the surface layer than α-PbO2. CeO2 dopants change the crystallite size and crystal structure, enhance the catalytic activity, and even change the deposition mechanism of PbO2. The doping of CeO2 in the PbO2 electrodes can enhance the electro-catalytic activity, which is helpful for oxygen evolution, and therefore reduce the cell voltage.展开更多
The ubiquitous arsenic in groundwater poses a great risk to human health due to its environmental toxicity and carcinogenicity.In the present work,a new adsorbent,δ-MnO2 modified activated carbon,was prepared,and its...The ubiquitous arsenic in groundwater poses a great risk to human health due to its environmental toxicity and carcinogenicity.In the present work,a new adsorbent,δ-MnO2 modified activated carbon,was prepared,and its performance for the uptake of arsenate and arsenite species from aqueous solutions was investigated by batch experiments.Various techniques,including FESEM-EDX,p-XRD,XPS and BET surface area analysis,were employed to characterize the properties of the adsorbent and the arsenic adsorption mechanisms.The results showed thatδ-MnO2 covered on the surface and padded in the pores of the activated carbon.Adsorption kinetic studies revealed that approximately 90.1%and 76.8%of As(Ⅲ)and As(V),respectively,were removed by the adsorbent in the first 9 hr,and adsorption achieved equilibrium within 48 hr.The maximum adsorption capacities of As(V)and As(Ⅲ)at pH 4.0 calculated from Langmuir adsorption isotherms were 13.30 and 12.56 mg/g,respectively.The effect of pH on As(Ⅴ)and As(Ⅲ)removal was similar,and the removal efficiency significantly reduced with the increase of solution pH.Arsenite oxidation and adsorption kinetics showed that the As(Ⅴ)concentration in solution due to As(Ⅲ)oxidation and reductive dissolution of MnO2 increased rapidly during the first 12 min,and then gradually decreased.Based on the XPS analysis,nearly 93.3%of As(Ⅲ)had been oxidized to As(V)on the adsorbent surface and around 38.9%of Mn(Ⅳ)had been reduced to Mn(Ⅱ)after As(Ⅲ)adsorption.This approach provides a possible method for the purification of arsenic-contaminated groundwater.展开更多
Because of its significant toxicological effects on the environment and human health,arsenic(As)is a major global issue.In this study,an Fe-based metal-organic framework(MOF)(Materials of Institut Lavoisier:MIL-100(Fe...Because of its significant toxicological effects on the environment and human health,arsenic(As)is a major global issue.In this study,an Fe-based metal-organic framework(MOF)(Materials of Institut Lavoisier:MIL-100(Fe))which was impregnated with reduced graphene oxide(rGO)by using a simple hydrothermal method and coated with birnessitetype manganese oxide(δ-MnO2)using the one-pot reaction process(MIL-100(Fe)GO/δ-MnO2 nanocomposites)was synthesized and applied successfully in As removal.The removal efficiency was rapid,the equilibrium was achieved in 40 min and 120 min for As(Ⅲ)and As(Ⅴ),respectively,at a level of 5 mg/L.The maximum adsorption capacities of As(Ⅲ)and As(Ⅴ)at pH 2 were 192.67 mg/g and 162.07 mg/g,respectively.The adsorbent revealed high stability in pH range 2-9 and saturated adsorbent can be fully regenerated at least five runs.The adsorption process can be described by the pseudo-second-order kinetic model and Langmuir monolayer adsorption.The adsorption mechanisms consisted of electrostatic interaction,oxidation and inner sphere surface complexation.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52400110 and 52070111).
摘要Electrocatalytic dehalogenation has emerged as a sustainable technology for environmental remediation.However,efficient electrocatalysts are still lacking,especially for wastewater treatment.In this study,a Pd/γ-MnO2/Ni foam composite electrode was designed.The introduction of hexagonal flake-likeγ-MnO2successfully prevented Pd aggregation and optimized electrode structure.Compared to previously reported electrodes,Pd/γ-MnO2/Ni foam composite electrode had lower Pd loading and higher dehalogenation efficiency and current efficiency.In 2-chlorophenol(2-CP)solution and dye wastewater,over 99%dehalogenation efficiencies were achieved within 120 min(10 mA),without adjusting the pH value.Computational results suggested thatγ-MnO2can promote the adsorption of H2O,which is the key rate-limiting step for 2-CP hydrodechlorination.In addition,γMnO2facilitated water dissociation and served as an intermediary for transferring atomic hydrogen(H∗)from Pd to Ni foam.This hydrogen spillover mechanism extended the reactive area of electrode,hindered H2evolution and enhanced the dehalogenation efficiency.It was found that Pd/γ-MnO2/Ni foam electrode showed excellent dehalogenation performance under both acidic and neutral conditions,and exhibited good resistance to the coexisting ions(such as Cl−,NO3−and HCO 3−).Hence,the Pd/γ-MnO2/Ni foam electrode demonstrates strong potential for the treatment of high-salinity wastewater.The high dehalogenation efficiency and long service life of Pd/γ-MnO2/Ni foam electrode in dye wastewater confirmed its feasibility and applicability.This study explored the synthesis and interfacial mechanism of electrodes,paving the way for efficient remediation of halogenated organic pollutants in wastewater.
基金Projects(51004056,51004057)supported by the National Natural Science Foundation of ChinaProject(KKZ6201152009)supported by the Opening Foundation of Key Laboratory of Inorganic Coating Materials,Chinese Academy of Sciences+2 种基金Project(2010ZC052)supported by the Applied Basic Research Foundation of Yunnan Province,ChinaProject(20125314110011)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,ChinaProject(2010247)supported by Analysis&Testing Foundation of Kunming University of Science and Technology,China
摘要Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy(EDXS), anode polarization curves, quasi-stationary polarization(Tafel) curves, electrochemical impedance spectroscopy(EIS), scanning electron microscopy(SEM), and X-ray diffraction(XRD). Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential(0.610 V at 500 A/m2) for oxygen evolution, the best electrocatalytic activity, the longest service life(360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2), and the lowest cell voltage(2.75 V at 500 A/m2). Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.
基金financially supported by the Guangdong Power Grid Co.,Ltd.(Grant No.GDKJXM20160000)。
摘要Aqueous Zn//MnO2 batteries are emerging as promising large-scale energy storage devices owing to their cost-effectiveness,high safety,high output voltage,and energy density.However,the MnO2 cathode suffers from intrinsically poor rate performance and rapid capacity deterioration.Here,we remove the roadblock by compositing MnO2 nanorods with highly conductive graphene,which remarkably enhances the electrochemical properties of the MnO2 cathode.Benefiting from the boosted electric conductivity and ion diffusion rate as well as the structural protection of graphene,the Zn//MnO2-graphene battery presents an admirable capacity of 301 mAh g^-1 at 0.5 A g^-1,corresponding to a high energy density of 411.6 Wh kg^-1.Even at a high current density of 10 A g^-1,a decent capacity of 95.8 mAh g^-1 is still obtained,manifesting its excellent rate property.Furthermore,an impressive power density of 15 kW kg^-1 is achieved by the Zn//MnO2-graphene battery.
基金Project(50964008)supported by the National Natural Science Foundation of ChinaProject(2010287)supported by Analysis and Testing Foundation of Kunming University of Science and Technology,China
摘要Al/α-PbO2/β-PbO2 composite electrodes doped with rare earth oxide (CeO2) were prepared by anodic oxidation method investigate the influence of nano-CeO2 dopants on the properties of Al/α-PbO2/β-PbO2-CeO2 electrodes and the impact of α-PbO2 as the intermediate layer. The results show that using α-PbO2 as the intermediate layer will benefit the crystallization of β-PbO2 and β-PbO2 is more suitable as the surface layer than α-PbO2. CeO2 dopants change the crystallite size and crystal structure, enhance the catalytic activity, and even change the deposition mechanism of PbO2. The doping of CeO2 in the PbO2 electrodes can enhance the electro-catalytic activity, which is helpful for oxygen evolution, and therefore reduce the cell voltage.
基金This work was supported by the National Natural Science Foundation of China(Nos.41530643 and 41807358)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB14020203)the Joint Fund of NSFC and Henan(No.U1804110).
摘要The ubiquitous arsenic in groundwater poses a great risk to human health due to its environmental toxicity and carcinogenicity.In the present work,a new adsorbent,δ-MnO2 modified activated carbon,was prepared,and its performance for the uptake of arsenate and arsenite species from aqueous solutions was investigated by batch experiments.Various techniques,including FESEM-EDX,p-XRD,XPS and BET surface area analysis,were employed to characterize the properties of the adsorbent and the arsenic adsorption mechanisms.The results showed thatδ-MnO2 covered on the surface and padded in the pores of the activated carbon.Adsorption kinetic studies revealed that approximately 90.1%and 76.8%of As(Ⅲ)and As(V),respectively,were removed by the adsorbent in the first 9 hr,and adsorption achieved equilibrium within 48 hr.The maximum adsorption capacities of As(V)and As(Ⅲ)at pH 4.0 calculated from Langmuir adsorption isotherms were 13.30 and 12.56 mg/g,respectively.The effect of pH on As(Ⅴ)and As(Ⅲ)removal was similar,and the removal efficiency significantly reduced with the increase of solution pH.Arsenite oxidation and adsorption kinetics showed that the As(Ⅴ)concentration in solution due to As(Ⅲ)oxidation and reductive dissolution of MnO2 increased rapidly during the first 12 min,and then gradually decreased.Based on the XPS analysis,nearly 93.3%of As(Ⅲ)had been oxidized to As(V)on the adsorbent surface and around 38.9%of Mn(Ⅳ)had been reduced to Mn(Ⅱ)after As(Ⅲ)adsorption.This approach provides a possible method for the purification of arsenic-contaminated groundwater.
基金supported by the Social Development Fund of Guangdong Province(No.2017A020216018)the Guangzhou Science and Technology Project(No.201904010319)
摘要Because of its significant toxicological effects on the environment and human health,arsenic(As)is a major global issue.In this study,an Fe-based metal-organic framework(MOF)(Materials of Institut Lavoisier:MIL-100(Fe))which was impregnated with reduced graphene oxide(rGO)by using a simple hydrothermal method and coated with birnessitetype manganese oxide(δ-MnO2)using the one-pot reaction process(MIL-100(Fe)GO/δ-MnO2 nanocomposites)was synthesized and applied successfully in As removal.The removal efficiency was rapid,the equilibrium was achieved in 40 min and 120 min for As(Ⅲ)and As(Ⅴ),respectively,at a level of 5 mg/L.The maximum adsorption capacities of As(Ⅲ)and As(Ⅴ)at pH 2 were 192.67 mg/g and 162.07 mg/g,respectively.The adsorbent revealed high stability in pH range 2-9 and saturated adsorbent can be fully regenerated at least five runs.The adsorption process can be described by the pseudo-second-order kinetic model and Langmuir monolayer adsorption.The adsorption mechanisms consisted of electrostatic interaction,oxidation and inner sphere surface complexation.