Nitrogen-doped anatase TiO 2 microsheets with 65%（001） and 35%（101） exposed faces were fabricated by the hydrothermal method using TiN as precursor in the presence of HF and HCl. The samples were characterized by ...Nitrogen-doped anatase TiO 2 microsheets with 65%（001） and 35%（101） exposed faces were fabricated by the hydrothermal method using TiN as precursor in the presence of HF and HCl. The samples were characterized by scanning electron microscopy,X-ray diffraction,N2 adsorption,X-ray photoelectron spectroscopy,UV-visible spectroscopy,and electrochemical impedance spectroscopy. Their photocatalytic activity was evaluated using the photocatalytic reduction of CO2. The N-doped TiO 2 sample exhibited a much higher visible light photocatalytic activity for CO2 reduction than its precursor TiN and commercial TiO 2（P25）. This was due to the synergistic effect of the formation of surface heterojunctions on the TiO 2 microsheet surface,enhanced visible light absorption by nitrogen-doping,and surface fluorination.展开更多
To harness abundant and clean solar energy along with relieving energy and environmental issues,photocatalysis holds great promise.Semiconductor-based photocatalysts are crucial to its successful application.However,t...To harness abundant and clean solar energy along with relieving energy and environmental issues,photocatalysis holds great promise.Semiconductor-based photocatalysts are crucial to its successful application.However,the photocatalytic efficiency based on a unitary semiconductor material falls short of expectations,mainly because of the rapid recombination of photogenerated electrons and holes.This originates in the extremely strong Columbic force between them.Moreover,it is impossible for a single photocatalyst to achieve wide light absorption and ample redox ability concurrently.展开更多
Hydrogen(H_(2))is a clean,efficient,and renewable energy with zero carbon emission,which is expected to replace the extensively used fossil fuels.Photocatalytic water splitting is a promising strategy for sustainable ...Hydrogen(H_(2))is a clean,efficient,and renewable energy with zero carbon emission,which is expected to replace the extensively used fossil fuels.Photocatalytic water splitting is a promising strategy for sustainable H2 production.Nevertheless,the performance of single‐component photocatalysts is often confined by fast electron‐hole recombination due to strong Coulombic force,and their inability to simultaneously attain a wide absorption range and enough redox capabilities.These problems can be addressed by constructing a heterojunction between two semiconductors with different Fermi levels(EF),conduction band(CB)and valence band(VB)positions.Heterojunction promotes light harvesting through light absorption on both semiconductors and facilitates charge separation by decoupling them on different bands.There are mainly three types of heterojunctions,namely the type‐II heterojunction,the Z‐scheme heterojunction,and the step‐scheme(S‐scheme)heterojunction[1–3].In a type‐II heterojunction,photogenerated electrons migrate from the higher CB to the lower one,while photogenerated holes transfer from the lower to the higher VB.However,this schematic is thermodynamically flawed since the charge transfer discounts the redox powers of the electrons and holes.This transfer is also dynamically unfavorable due to strong repulsion between the photogenerated electrons(or holes)in different semiconductors.The Z‐scheme heterojunction utilizes dissolved redox ion pairs(traditional Z‐scheme)or conductive materials(all‐solid‐state Z‐scheme)as the shuttle for charge transfer and separation.However,the photogenerated carriers with stronger redox powers would preferentially react with the ion pairs or combine at the conductor because of stronger driving forces,leading to deducted redox powers and reduced photocatalytic activity.S‐scheme heterojunction could avoid these drawbacks and has exhibited excellent performance in organics degradation[4,5],CO_(2) reduction[6,7],hydrogen evolution[8],etc.展开更多
Photocatalytic CO_(2) reduction to solar fuels attracts great interest due to the growing fossil fuel shortage and global warming. Developing high-efficiency photocatalyst is the key for the solar fuel production ~(1,...Photocatalytic CO_(2) reduction to solar fuels attracts great interest due to the growing fossil fuel shortage and global warming. Developing high-efficiency photocatalyst is the key for the solar fuel production ~(1,2). TiO_(2), as an inert, nontoxic and earth-abundant semiconductor, has been widely used for photocatalytic CO_(2) reduction.展开更多
The convertion of solar energy into hydrogen energy with high energy density by photocatalysis is a green and eco-friendly avenue to solve the energy crisis and environmental pollution issues 1,2.Unfortunately,most ph...The convertion of solar energy into hydrogen energy with high energy density by photocatalysis is a green and eco-friendly avenue to solve the energy crisis and environmental pollution issues 1,2.Unfortunately,most photocatalysts usually suffer from the rapid quenching of photogenerated carriers and depressed interfacial H_(2)-generation dynamics 3,4.To overcome the above shortcomings,cocatalysts are widely employed to promote the separation of photocarriers and to create active sites for surface catalytic reactions 5.For a superb cocatalyst,its active sites usually play a key role in the overall performance of photocatalytic H_(2) evolution because the active sites can not only provide a large number of adsorption centers to enrich H+,but also present an outstanding catalytic efficiency to convert H+into H_(2) by reducing its reaction overpotential 6.Thus,the active-site number and efficiency of cocatalysts should be maximized as much as possible to greatly boost the cocatalytic H2-evolution activity by photocatalysis.展开更多
During the past decade,organic-inorganic hybrid perovskite solar cell(PSC)has attracted great attention in the photovoltaic field 1,2.As the third-generation solar cell,PSC in laboratory has already achieved certified...During the past decade,organic-inorganic hybrid perovskite solar cell(PSC)has attracted great attention in the photovoltaic field 1,2.As the third-generation solar cell,PSC in laboratory has already achieved certified power conversion efficiency(PCE)exceeding 25%.The superb photovoltaic performance of PSC is attributed to the unique optoelectronic properties of organic-inorganic halide perovskite light absorption layer,including low exciton binding energy,high absorption coefficients,and outstanding carrier mobility 3,4.Hence,the quality of perovskite film plays a decisive role in the photovoltaic performance of PSC.Defects are inevitably formed on the surface and inside of polycrystalline perovskite film during the conventional preparation methods.It’s widely acknowledged that defects are the recombination centers of photogenerated electrons and holes,resulting in the loss of useful photogenerated charges 5,6.Therefore,decreasing the charge loss is advantageous to improving the PCE of PSC.展开更多
The paper presents a comparative study on the electric, dielectric and microwave properties of natural rubber based composites comprising dual phase fillers prepared from furnace carbon black or conductive carbon blac...The paper presents a comparative study on the electric, dielectric and microwave properties of natural rubber based composites comprising dual phase fillers prepared from furnace carbon black or conductive carbon black with a different amount of silica. It has been established that, the specifics of the carbon phase have a marked strong effect upon the properties mentioned above. The interpenetration of the two filler phases and the grade of isolation of the conductive carbon phase by the dielectric one depend on the ratio between them. On the other hand, that leads to a change in all properties of the studied composites, which allows tailoring those characteristics.展开更多
Implants of titanium(Ti)and its alloys have been widely used for decades in bone tissue engineering.Orthopedic implantation is unavoidably accompanied by bacterial infection,which requires extensive surgical intervent...Implants of titanium(Ti)and its alloys have been widely used for decades in bone tissue engineering.Orthopedic implantation is unavoidably accompanied by bacterial infection,which requires extensive surgical intervention and antibiotic therapy.These infections increase the risk of implant failure and bone loss and can result in limb amputation in severe cases.Repeated antibiotic treatment also induces irreversible drug resistance in humans[1,2].Studies designed to optimize Ti containing implants have focused on surface modification or improvements of topological structures.Modified implants can induce stem cell differentiation and bone regeneration[3].However,designing implants that resist colonization by bacteria has not been explored extensively.展开更多
Natural rubber based composites containing different carbon nanofillers (fullerenes, carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs)) at different concentrations have been prepared. Their dielectric properti...Natural rubber based composites containing different carbon nanofillers (fullerenes, carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs)) at different concentrations have been prepared. Their dielectric properties (dielectric permittivity, dielectric loss) have been studied in the 1 - 12 GHz frequency range. Some factors (electromagnetic field frequency, fillers concentration, fillers intrinsic structure) influencing the dielectric behavior of the composites have been investigated. The dielectric properties of the developed natural rubber composites containing conductive fillers (fullerenes, CNTs, GNPs) indicate that these composites can be used as broadband microwave absorbing materials.展开更多
The paper presents the synthesis and characterization of carbon black/silicone dioxide hybrid fillers obtained by an impregnation technology. The electromagnetic interference shielding effectiveness of the composites ...The paper presents the synthesis and characterization of carbon black/silicone dioxide hybrid fillers obtained by an impregnation technology. The electromagnetic interference shielding effectiveness of the composites filled with carbon black/silicone dioxide hybrid fillers was measured in wide frequency range of 1 - 12 GHz. The dc and ac electrical conductivity of composites also have been investigated. The relationship between electrical (dc and ac) conductivity and shielding effectiveness was analyzed. A positive correlation was found between the absorptive shielding effectiveness and ac conductivity for composites comprising conductive carbon black/silica filler, when the filler loading is above the percolation threshold.展开更多
Reducing CO_(2) to hydrocarbon fuels by solar irradiation provides a feasible channel for mitigating excessive CO_(2) emissions and addressing resource depletion.Nevertheless,severe charge recombi‐nation and the high...Reducing CO_(2) to hydrocarbon fuels by solar irradiation provides a feasible channel for mitigating excessive CO_(2) emissions and addressing resource depletion.Nevertheless,severe charge recombi‐nation and the high energy barrier for CO_(2) photoreduction on the surface of photocatalysts com‐promise the catalytic performance.Herein,a 2D/2D Bi_(2)MoO_(6)/BiOI composite was fabricated to achieve improved CO_(2) photoreduction efficiency.Charge transfer in the composite was facilitated by the van der Waals heterojunction with a large‐area interface.Work function calculation demon‐strated that S‐scheme charge transfer is operative in the composite,and effective charge separation and strong redox capability were revealed by time‐resolved photoluminescence and electron para‐magnetic resonance spectroscopy.Moreover,the intermediates of CO_(2) photoreduction were identi‐fied based on the in situ diffuse reflectance infrared Fourier‐transform spectra.Density functional theory calculations showed that CO_(2) hydrogenation is the rate‐determining step for yielding CH_(4) and CO.Introducing Bi_(2)MoO_(6) into the composite further decreased the energy barrier for CO_(2) photoreduction on BiOI by 0.35 eV.This study verifies the synergistic effect of the S‐scheme heterojunction and van der Waals heterojunction in the 2D/2D composite.展开更多
The negative effects of natural disasters on human life exist from the foot and did not occur at a specific time but found since the creation of mankind. Humans coexist with extreme events all the time, only when the ...The negative effects of natural disasters on human life exist from the foot and did not occur at a specific time but found since the creation of mankind. Humans coexist with extreme events all the time, only when the intensity of the event becomes greater than a certain level there is a resulting disaster. Small earthquakes occur all of the time with no adverse effects. Only large earthquakes cause disasters. Statistical analysis reveals that larger events occur less frequently than small events. Through the large number of seismic events, we find that at the end of the year may have a series of seismic events with different values depending on the strength of activity whether it is high or low on Richter scale and the assessment is only for the greatest value in a year even if recurring this value and the volume of dangerous increases and the frequency of their occurrence according to an ongoing activity, major disasters result from a small number of events and sustained results in a large and devastating event, and can be represented by these results and amounts On a log-scale which points are almost on a straight line and a clear indication of the evaluation event. Through previous data analysis we can understand the following events behavior for coordination and guidance on the development of evacuation plans on the expected future and use a Weibull equation to estimate the frequency of the event and the return again as a percentage for each event and the probability of the occurrence of a particular earthquake to some degree on the Richter scale in the sea during any period. Past records of earthquakes at the West Coast of the Kingdom of Saudi Arabia (Red Sea) for years 1913-2016 are used to predict future conditions concerning the annual frequency, the return period, the percentage probability for each event, and the probability of a certain-magnitude earthquake occurring in the region during any period.展开更多
The research tackles earthquakes as one of the most dangerous natural disasters. It defines disasters in general, which in turn include earthquakes, how to manage them, stages of their evolution, and their classificat...The research tackles earthquakes as one of the most dangerous natural disasters. It defines disasters in general, which in turn include earthquakes, how to manage them, stages of their evolution, and their classification among other kinds of disasters such as hurricanes, floods, drought, desertification, etc. Afterwards, it tackles the impacts of disasters on man, buildings and infrastructure. It defines also the codes and laws existing in the Kingdom of Saudi Arabia to confront and treat the impacts of earthquakes in their different stages (before, during and after) and the authorities involved in managing them. Then, it moves to study the case of Al-Ais Earthquake, and identifies the points of deficiency in dealing with such a disaster. Moreover, the research tackles some global experiences in how to handle the situation, reaching to the presentation of a conceptual approach to confront disasters of earthquakes in their various stages.展开更多
基金supported by the National Basic Research Program of China(973 Program2013CB632402)+7 种基金the National Natural Science Foundation of China(513201050015137219051402025and 21433007)the Natural Science Foundation of Hubei Province(2015CFA001)the Fundamental Research Funds for the Central Universities(WUT:2014-VII-010)the Self-Determined and Innovative Research Funds of State Key Laboratory of Advanced Technology for Material Synthesis and ProcessingWuhan University of Technology(2013-ZD-1)~~
文摘Nitrogen-doped anatase TiO 2 microsheets with 65%（001） and 35%（101） exposed faces were fabricated by the hydrothermal method using TiN as precursor in the presence of HF and HCl. The samples were characterized by scanning electron microscopy,X-ray diffraction,N2 adsorption,X-ray photoelectron spectroscopy,UV-visible spectroscopy,and electrochemical impedance spectroscopy. Their photocatalytic activity was evaluated using the photocatalytic reduction of CO2. The N-doped TiO 2 sample exhibited a much higher visible light photocatalytic activity for CO2 reduction than its precursor TiN and commercial TiO 2（P25）. This was due to the synergistic effect of the formation of surface heterojunctions on the TiO 2 microsheet surface,enhanced visible light absorption by nitrogen-doping,and surface fluorination.
文摘To harness abundant and clean solar energy along with relieving energy and environmental issues,photocatalysis holds great promise.Semiconductor-based photocatalysts are crucial to its successful application.However,the photocatalytic efficiency based on a unitary semiconductor material falls short of expectations,mainly because of the rapid recombination of photogenerated electrons and holes.This originates in the extremely strong Columbic force between them.Moreover,it is impossible for a single photocatalyst to achieve wide light absorption and ample redox ability concurrently.
基金supported by the Institutional Fund Projects under grant no(IFPRC‐133‐130‐2020).Therefore,authors gratefully acknowledge technical and financial support from Ministry of Education and King Abdulaziz University,Jeddah,Saudi Arabia.
文摘Hydrogen(H_(2))is a clean,efficient,and renewable energy with zero carbon emission,which is expected to replace the extensively used fossil fuels.Photocatalytic water splitting is a promising strategy for sustainable H2 production.Nevertheless,the performance of single‐component photocatalysts is often confined by fast electron‐hole recombination due to strong Coulombic force,and their inability to simultaneously attain a wide absorption range and enough redox capabilities.These problems can be addressed by constructing a heterojunction between two semiconductors with different Fermi levels(EF),conduction band(CB)and valence band(VB)positions.Heterojunction promotes light harvesting through light absorption on both semiconductors and facilitates charge separation by decoupling them on different bands.There are mainly three types of heterojunctions,namely the type‐II heterojunction,the Z‐scheme heterojunction,and the step‐scheme(S‐scheme)heterojunction[1–3].In a type‐II heterojunction,photogenerated electrons migrate from the higher CB to the lower one,while photogenerated holes transfer from the lower to the higher VB.However,this schematic is thermodynamically flawed since the charge transfer discounts the redox powers of the electrons and holes.This transfer is also dynamically unfavorable due to strong repulsion between the photogenerated electrons(or holes)in different semiconductors.The Z‐scheme heterojunction utilizes dissolved redox ion pairs(traditional Z‐scheme)or conductive materials(all‐solid‐state Z‐scheme)as the shuttle for charge transfer and separation.However,the photogenerated carriers with stronger redox powers would preferentially react with the ion pairs or combine at the conductor because of stronger driving forces,leading to deducted redox powers and reduced photocatalytic activity.S‐scheme heterojunction could avoid these drawbacks and has exhibited excellent performance in organics degradation[4,5],CO_(2) reduction[6,7],hydrogen evolution[8],etc.
基金funded by the Deanship of Scientific Research (DSR) at King Abdulaziz University, Jeddah (RG-50-130-41)。
文摘Photocatalytic CO_(2) reduction to solar fuels attracts great interest due to the growing fossil fuel shortage and global warming. Developing high-efficiency photocatalyst is the key for the solar fuel production ~(1,2). TiO_(2), as an inert, nontoxic and earth-abundant semiconductor, has been widely used for photocatalytic CO_(2) reduction.
基金funded by the Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah,under grant No.RG-72-130-42.
文摘The convertion of solar energy into hydrogen energy with high energy density by photocatalysis is a green and eco-friendly avenue to solve the energy crisis and environmental pollution issues 1,2.Unfortunately,most photocatalysts usually suffer from the rapid quenching of photogenerated carriers and depressed interfacial H_(2)-generation dynamics 3,4.To overcome the above shortcomings,cocatalysts are widely employed to promote the separation of photocarriers and to create active sites for surface catalytic reactions 5.For a superb cocatalyst,its active sites usually play a key role in the overall performance of photocatalytic H_(2) evolution because the active sites can not only provide a large number of adsorption centers to enrich H+,but also present an outstanding catalytic efficiency to convert H+into H_(2) by reducing its reaction overpotential 6.Thus,the active-site number and efficiency of cocatalysts should be maximized as much as possible to greatly boost the cocatalytic H2-evolution activity by photocatalysis.
基金funded by the Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah(Grant No.RG-72-130-42).
文摘During the past decade,organic-inorganic hybrid perovskite solar cell(PSC)has attracted great attention in the photovoltaic field 1,2.As the third-generation solar cell,PSC in laboratory has already achieved certified power conversion efficiency(PCE)exceeding 25%.The superb photovoltaic performance of PSC is attributed to the unique optoelectronic properties of organic-inorganic halide perovskite light absorption layer,including low exciton binding energy,high absorption coefficients,and outstanding carrier mobility 3,4.Hence,the quality of perovskite film plays a decisive role in the photovoltaic performance of PSC.Defects are inevitably formed on the surface and inside of polycrystalline perovskite film during the conventional preparation methods.It’s widely acknowledged that defects are the recombination centers of photogenerated electrons and holes,resulting in the loss of useful photogenerated charges 5,6.Therefore,decreasing the charge loss is advantageous to improving the PCE of PSC.
文摘The paper presents a comparative study on the electric, dielectric and microwave properties of natural rubber based composites comprising dual phase fillers prepared from furnace carbon black or conductive carbon black with a different amount of silica. It has been established that, the specifics of the carbon phase have a marked strong effect upon the properties mentioned above. The interpenetration of the two filler phases and the grade of isolation of the conductive carbon phase by the dielectric one depend on the ratio between them. On the other hand, that leads to a change in all properties of the studied composites, which allows tailoring those characteristics.
文摘Implants of titanium(Ti)and its alloys have been widely used for decades in bone tissue engineering.Orthopedic implantation is unavoidably accompanied by bacterial infection,which requires extensive surgical intervention and antibiotic therapy.These infections increase the risk of implant failure and bone loss and can result in limb amputation in severe cases.Repeated antibiotic treatment also induces irreversible drug resistance in humans[1,2].Studies designed to optimize Ti containing implants have focused on surface modification or improvements of topological structures.Modified implants can induce stem cell differentiation and bone regeneration[3].However,designing implants that resist colonization by bacteria has not been explored extensively.
文摘Natural rubber based composites containing different carbon nanofillers (fullerenes, carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs)) at different concentrations have been prepared. Their dielectric properties (dielectric permittivity, dielectric loss) have been studied in the 1 - 12 GHz frequency range. Some factors (electromagnetic field frequency, fillers concentration, fillers intrinsic structure) influencing the dielectric behavior of the composites have been investigated. The dielectric properties of the developed natural rubber composites containing conductive fillers (fullerenes, CNTs, GNPs) indicate that these composites can be used as broadband microwave absorbing materials.
文摘The paper presents the synthesis and characterization of carbon black/silicone dioxide hybrid fillers obtained by an impregnation technology. The electromagnetic interference shielding effectiveness of the composites filled with carbon black/silicone dioxide hybrid fillers was measured in wide frequency range of 1 - 12 GHz. The dc and ac electrical conductivity of composites also have been investigated. The relationship between electrical (dc and ac) conductivity and shielding effectiveness was analyzed. A positive correlation was found between the absorptive shielding effectiveness and ac conductivity for composites comprising conductive carbon black/silica filler, when the filler loading is above the percolation threshold.
文摘Reducing CO_(2) to hydrocarbon fuels by solar irradiation provides a feasible channel for mitigating excessive CO_(2) emissions and addressing resource depletion.Nevertheless,severe charge recombi‐nation and the high energy barrier for CO_(2) photoreduction on the surface of photocatalysts com‐promise the catalytic performance.Herein,a 2D/2D Bi_(2)MoO_(6)/BiOI composite was fabricated to achieve improved CO_(2) photoreduction efficiency.Charge transfer in the composite was facilitated by the van der Waals heterojunction with a large‐area interface.Work function calculation demon‐strated that S‐scheme charge transfer is operative in the composite,and effective charge separation and strong redox capability were revealed by time‐resolved photoluminescence and electron para‐magnetic resonance spectroscopy.Moreover,the intermediates of CO_(2) photoreduction were identi‐fied based on the in situ diffuse reflectance infrared Fourier‐transform spectra.Density functional theory calculations showed that CO_(2) hydrogenation is the rate‐determining step for yielding CH_(4) and CO.Introducing Bi_(2)MoO_(6) into the composite further decreased the energy barrier for CO_(2) photoreduction on BiOI by 0.35 eV.This study verifies the synergistic effect of the S‐scheme heterojunction and van der Waals heterojunction in the 2D/2D composite.
文摘The negative effects of natural disasters on human life exist from the foot and did not occur at a specific time but found since the creation of mankind. Humans coexist with extreme events all the time, only when the intensity of the event becomes greater than a certain level there is a resulting disaster. Small earthquakes occur all of the time with no adverse effects. Only large earthquakes cause disasters. Statistical analysis reveals that larger events occur less frequently than small events. Through the large number of seismic events, we find that at the end of the year may have a series of seismic events with different values depending on the strength of activity whether it is high or low on Richter scale and the assessment is only for the greatest value in a year even if recurring this value and the volume of dangerous increases and the frequency of their occurrence according to an ongoing activity, major disasters result from a small number of events and sustained results in a large and devastating event, and can be represented by these results and amounts On a log-scale which points are almost on a straight line and a clear indication of the evaluation event. Through previous data analysis we can understand the following events behavior for coordination and guidance on the development of evacuation plans on the expected future and use a Weibull equation to estimate the frequency of the event and the return again as a percentage for each event and the probability of the occurrence of a particular earthquake to some degree on the Richter scale in the sea during any period. Past records of earthquakes at the West Coast of the Kingdom of Saudi Arabia (Red Sea) for years 1913-2016 are used to predict future conditions concerning the annual frequency, the return period, the percentage probability for each event, and the probability of a certain-magnitude earthquake occurring in the region during any period.
文摘The research tackles earthquakes as one of the most dangerous natural disasters. It defines disasters in general, which in turn include earthquakes, how to manage them, stages of their evolution, and their classification among other kinds of disasters such as hurricanes, floods, drought, desertification, etc. Afterwards, it tackles the impacts of disasters on man, buildings and infrastructure. It defines also the codes and laws existing in the Kingdom of Saudi Arabia to confront and treat the impacts of earthquakes in their different stages (before, during and after) and the authorities involved in managing them. Then, it moves to study the case of Al-Ais Earthquake, and identifies the points of deficiency in dealing with such a disaster. Moreover, the research tackles some global experiences in how to handle the situation, reaching to the presentation of a conceptual approach to confront disasters of earthquakes in their various stages.
