It is challenging and desirable to construct Pt-based nanocomposites with oxygen storage function as efficient oxygen reduction reaction(ORR)catalysts for practical proton exchange membrane fuel cells(PEMFCs).Herein,w...It is challenging and desirable to construct Pt-based nanocomposites with oxygen storage function as efficient oxygen reduction reaction(ORR)catalysts for practical proton exchange membrane fuel cells(PEMFCs).Herein,we achieve novel porous nanocomposites of PtCu_(3) nanoalloys-embedded in the PWO_(x) matrix(PtCu_(3)@PWO_(x)),which has an oxygen container feature.The PtCu_(3)@PWO_(x)/C exhibits an ultrahigh mass activity(MA)of 3.94 A·mgPt−1 for ORR,which is 26.3 times as high as the commercial Pt/C and the highest value ever reported for PtCu-based binary system.Theoretical calculations reveal that the compressive strain and d-band center downshift of Pt intrinsically contribute to the excellent ORR performance.In H_(2)-air PEMFCs at room temperature,furthermore,the PtCu_(3)@PWO_(x)/C delivers a high power density(218.6 mW·cm^(−2)),much superior to commercial Pt/C(131.6 mW·cm^(−2)).In H_(2)-O_(2) PEMFCs,PtCu_(3)@PWO_(x)/C outputs a maximum power density of 420.1 mW·cm^(−2).This work provides an effective idea for designing oxygen-storing ORR catalysts used for practical room-temperature H_(2)-air fuel cells.展开更多
Due to viscous heating spontaneous ignition of a supersonic flow of premixed combustible gases canoccur in boundary layers. This process is studied numerically for a hydrogen-air mixture in the caseof a laminar bounda...Due to viscous heating spontaneous ignition of a supersonic flow of premixed combustible gases canoccur in boundary layers. This process is studied numerically for a hydrogen-air mixture in the caseof a laminar boundary layer over a flat plate. In a previous study the main structure of the reactingflow was given as well as a first mapping of the ignition conditions versus boundary conditions. In thepresent work computations are performed in order to further specify the controlling mechanisms andparameters of such a boundary layer ignition. We emphasize more precisely i) the elementary stepsof the chemical process which effectively control the ignition n) the unusual role played by the equivalence ratio of the mixture iii) the influence of the Soret effect (species transport due to temperaturegradients).展开更多
Study Objective: The purpose of the study is to present independent laboratory testing for a novel technology in air and on surfaces. Since 2020, public health goals have focused on improving indoor air quality. This ...Study Objective: The purpose of the study is to present independent laboratory testing for a novel technology in air and on surfaces. Since 2020, public health goals have focused on improving indoor air quality. This includes protection from airborne pathogens, such as tuberculosis, RSV, SARS-CoV-2, common cold or influenza viruses, measles, and others. Engineering controls are highly effective at reducing hazardous pathogens found in indoor air and from recontamination of surfaces. This occurs from a continuous cycle of settling of small, sustained airborne pathogens, which may become dehumidified, becoming airborne again, carried by room air currents around indoor spaces, then repeating the cycle. Methods: The novel technology utilizes a catalytic process to produce safe levels of hydrogen peroxide gas that are effective in reducing pathogens in the air and on surfaces. Air testing was performed with the MS2 bacteriophage, the test organism for ASHRAE standard 241, and methicillin-Resistant Staphylococcus aureus (MRSA). Surface testing was performed with SARS-COV-2 (Coronavirus COVID-19) and H1N1 (Influenza). Typical ventilation and filtration does not effectively remove disbursed pathogens from the entire facility, due to inconsistent air circulation and surface deposits of pathogens. Results: MS2 was reduced by 99.9%;MRSA was reduced by 99.9%;SARS-CoV-2 was reduced by 99.9%;H1N1 was reduced by 99.9%. Conclusion: This novel catalytic converter reduces a variety of pathogens in the air (99%) and on surfaces (99%), by actively disinfecting with the introduction of gaseous hydrogen peroxide. This active disinfection provides a strong solution for protecting the entire facility and its occupants.展开更多
基金supported by the National Natural Science Foundation of China(No.21571038)Foundation of Guizhou Province(No.2019-5666)+3 种基金Education Department of Guizhou Province(No.2021312)State Key Laboratory of Coal Mine Disaster Dynamics and Control(Chongqing University,No.2011DA105287-ZR202101)State Key Laboratory of Physica Chemistry of Solid Surfaces(Xiamen University,No.202009)the Open Fund of the Key Lab of Organic Optoelectronics&Molecular Engineering(Tsinghua University).
文摘It is challenging and desirable to construct Pt-based nanocomposites with oxygen storage function as efficient oxygen reduction reaction(ORR)catalysts for practical proton exchange membrane fuel cells(PEMFCs).Herein,we achieve novel porous nanocomposites of PtCu_(3) nanoalloys-embedded in the PWO_(x) matrix(PtCu_(3)@PWO_(x)),which has an oxygen container feature.The PtCu_(3)@PWO_(x)/C exhibits an ultrahigh mass activity(MA)of 3.94 A·mgPt−1 for ORR,which is 26.3 times as high as the commercial Pt/C and the highest value ever reported for PtCu-based binary system.Theoretical calculations reveal that the compressive strain and d-band center downshift of Pt intrinsically contribute to the excellent ORR performance.In H_(2)-air PEMFCs at room temperature,furthermore,the PtCu_(3)@PWO_(x)/C delivers a high power density(218.6 mW·cm^(−2)),much superior to commercial Pt/C(131.6 mW·cm^(−2)).In H_(2)-O_(2) PEMFCs,PtCu_(3)@PWO_(x)/C outputs a maximum power density of 420.1 mW·cm^(−2).This work provides an effective idea for designing oxygen-storing ORR catalysts used for practical room-temperature H_(2)-air fuel cells.
文摘Due to viscous heating spontaneous ignition of a supersonic flow of premixed combustible gases canoccur in boundary layers. This process is studied numerically for a hydrogen-air mixture in the caseof a laminar boundary layer over a flat plate. In a previous study the main structure of the reactingflow was given as well as a first mapping of the ignition conditions versus boundary conditions. In thepresent work computations are performed in order to further specify the controlling mechanisms andparameters of such a boundary layer ignition. We emphasize more precisely i) the elementary stepsof the chemical process which effectively control the ignition n) the unusual role played by the equivalence ratio of the mixture iii) the influence of the Soret effect (species transport due to temperaturegradients).
文摘Study Objective: The purpose of the study is to present independent laboratory testing for a novel technology in air and on surfaces. Since 2020, public health goals have focused on improving indoor air quality. This includes protection from airborne pathogens, such as tuberculosis, RSV, SARS-CoV-2, common cold or influenza viruses, measles, and others. Engineering controls are highly effective at reducing hazardous pathogens found in indoor air and from recontamination of surfaces. This occurs from a continuous cycle of settling of small, sustained airborne pathogens, which may become dehumidified, becoming airborne again, carried by room air currents around indoor spaces, then repeating the cycle. Methods: The novel technology utilizes a catalytic process to produce safe levels of hydrogen peroxide gas that are effective in reducing pathogens in the air and on surfaces. Air testing was performed with the MS2 bacteriophage, the test organism for ASHRAE standard 241, and methicillin-Resistant Staphylococcus aureus (MRSA). Surface testing was performed with SARS-COV-2 (Coronavirus COVID-19) and H1N1 (Influenza). Typical ventilation and filtration does not effectively remove disbursed pathogens from the entire facility, due to inconsistent air circulation and surface deposits of pathogens. Results: MS2 was reduced by 99.9%;MRSA was reduced by 99.9%;SARS-CoV-2 was reduced by 99.9%;H1N1 was reduced by 99.9%. Conclusion: This novel catalytic converter reduces a variety of pathogens in the air (99%) and on surfaces (99%), by actively disinfecting with the introduction of gaseous hydrogen peroxide. This active disinfection provides a strong solution for protecting the entire facility and its occupants.
