Zn-air batteries have attracted extensive attention for their unique features including high energy density,safety,low cost and environmental friendliness.However,due to their poor chargeability and low efficiency,the...Zn-air batteries have attracted extensive attention for their unique features including high energy density,safety,low cost and environmental friendliness.However,due to their poor chargeability and low efficiency,the practical application remains a challenge.The main obstacles are the intrinsic slow reaction kinetics on air cathodes,including oxygen reduction reaction during the discharging process and oxygen evolution reaction during the recharging process.Searching for efficient bifunctional oxygen electrocatalysts is key to solve these problems.In this review,the configuration and fundamental oxygen electrochemical reactions on air cathodes are briefly introduced for Zn-air batteries first.Then,the latest bifunctional oxygen electrocatalysts are summarized in detail.Finally,the perspectives are provided for the future investigations on bifunctional oxygen electrocatalysts.展开更多
A new methanol-tolerant oxygen reduction electrocatalyst,nitrogen-doped hollow carbon microspheres@platinum nanoparticles hybrids(HNCMS@PtNPs),has been synthesized by a facile template route.In brief,PtNPs were loaded...A new methanol-tolerant oxygen reduction electrocatalyst,nitrogen-doped hollow carbon microspheres@platinum nanoparticles hybrids(HNCMS@PtNPs),has been synthesized by a facile template route.In brief,PtNPs were loaded on the surface of NH2-functionalized SiO_(2)microspheres(PtNPs/SiO_(2)).Then,the PtNPs/SiO_(2)hybrids were wrapped by polydopamine(PDA)film.After direct carbonization of PDA-wrapped PtNPs/SiO_(2)hybrids under a nitrogen atmosphere and further treatment in a hydrofluoric acid solution,PtNPs embedded within nitrogen-doped hollow carbon microsphere(HNCMS)were obtained and labeled as HNCMS@PtNPs.Scanning electron microscopy,transmission electron microscopy,X-ray diffraction,Raman spectroscopy,specific surface area analysis,and X-ray photoelectron spectroscopy were used to characterize the HNCMS@PtNPs hybrids.The electrochemical properties of the HNCMS@PtNPs hybrids for oxygen reduction reaction have also been investigated by cyclic voltammetry and linear sweep voltammetry.The results show that the Pt loading mass in the HNCMS@PtNPs hybrids is up to 11.9%(w,mass fraction).Furthermore,the as-prepared HNCMS@PtNPs catalyst exhibits good electrocatalytic activity,high stability,and excellent methanol-tolerance toward oxygen reduction reactions,implying potential applications in practical direct methanol fuel cells(DMFCs)as methanol-tolerant cathodic catalysts.展开更多
The mechanisms of oxygen-reduced air flooding(ORAF)and the explosion limit and the corrosion control approaches were studied based on the pilots of oxygen-reduced air flooding(ORAF)in the Dagang,Changqing and Daqing o...The mechanisms of oxygen-reduced air flooding(ORAF)and the explosion limit and the corrosion control approaches were studied based on the pilots of oxygen-reduced air flooding(ORAF)in the Dagang,Changqing and Daqing oil fields in China.On the foundation of indoor investigations and pilots,the explosion limits,oxygen reduction limits and corrosion control approaches were clarified.When the temperature of reservoir is equal to and higher than 120℃,there is a violent reaction between oxygen and crude oil,that means the effect of low temperature oxidation would be fully taken use of to enhance oil recovery by air flooding directly;nitrogen dominated immiscible flooding with oxygen-reduced air should be applied in cases where reservoir temperature is below 120℃ with little oxygen consumption and little heat generated.The oxygen-reduced air flooding is suitable for 3 types of reservoirs:low permeability reservoir,water flooding development reservoir of high water-cut and high temperature and high salinity reservoir.In the process of development,in order to ensure safety,the oxygen reduction limits should be controlled fewer than 10%,while oxygen-reduced air can obviously reduce the corrosion rate of pipes;The surface pipelines and injection wells don’t need to consider about oxygen corrosion with no water,special materials and structure of pipe or corrosion inhibitor can be applied to the surface pipelines and injection wellbores with water.Air/oxygen-reduced air is a low-cost displacement medium and it could be applied in many special conditions of low permeability reservoir for energy supplement,huff and puff and displacement,that means oxygen-reduced air flooding has become the most potential strategic technology in 20 years.展开更多
基金supported by the National Natural Science Foundation of China NSFC(51702166)Tianjin Municipal Science and Technology Bureau(17JCZDJC37100)~~
文摘Zn-air batteries have attracted extensive attention for their unique features including high energy density,safety,low cost and environmental friendliness.However,due to their poor chargeability and low efficiency,the practical application remains a challenge.The main obstacles are the intrinsic slow reaction kinetics on air cathodes,including oxygen reduction reaction during the discharging process and oxygen evolution reaction during the recharging process.Searching for efficient bifunctional oxygen electrocatalysts is key to solve these problems.In this review,the configuration and fundamental oxygen electrochemical reactions on air cathodes are briefly introduced for Zn-air batteries first.Then,the latest bifunctional oxygen electrocatalysts are summarized in detail.Finally,the perspectives are provided for the future investigations on bifunctional oxygen electrocatalysts.
文摘A new methanol-tolerant oxygen reduction electrocatalyst,nitrogen-doped hollow carbon microspheres@platinum nanoparticles hybrids(HNCMS@PtNPs),has been synthesized by a facile template route.In brief,PtNPs were loaded on the surface of NH2-functionalized SiO_(2)microspheres(PtNPs/SiO_(2)).Then,the PtNPs/SiO_(2)hybrids were wrapped by polydopamine(PDA)film.After direct carbonization of PDA-wrapped PtNPs/SiO_(2)hybrids under a nitrogen atmosphere and further treatment in a hydrofluoric acid solution,PtNPs embedded within nitrogen-doped hollow carbon microsphere(HNCMS)were obtained and labeled as HNCMS@PtNPs.Scanning electron microscopy,transmission electron microscopy,X-ray diffraction,Raman spectroscopy,specific surface area analysis,and X-ray photoelectron spectroscopy were used to characterize the HNCMS@PtNPs hybrids.The electrochemical properties of the HNCMS@PtNPs hybrids for oxygen reduction reaction have also been investigated by cyclic voltammetry and linear sweep voltammetry.The results show that the Pt loading mass in the HNCMS@PtNPs hybrids is up to 11.9%(w,mass fraction).Furthermore,the as-prepared HNCMS@PtNPs catalyst exhibits good electrocatalytic activity,high stability,and excellent methanol-tolerance toward oxygen reduction reactions,implying potential applications in practical direct methanol fuel cells(DMFCs)as methanol-tolerant cathodic catalysts.
文摘The mechanisms of oxygen-reduced air flooding(ORAF)and the explosion limit and the corrosion control approaches were studied based on the pilots of oxygen-reduced air flooding(ORAF)in the Dagang,Changqing and Daqing oil fields in China.On the foundation of indoor investigations and pilots,the explosion limits,oxygen reduction limits and corrosion control approaches were clarified.When the temperature of reservoir is equal to and higher than 120℃,there is a violent reaction between oxygen and crude oil,that means the effect of low temperature oxidation would be fully taken use of to enhance oil recovery by air flooding directly;nitrogen dominated immiscible flooding with oxygen-reduced air should be applied in cases where reservoir temperature is below 120℃ with little oxygen consumption and little heat generated.The oxygen-reduced air flooding is suitable for 3 types of reservoirs:low permeability reservoir,water flooding development reservoir of high water-cut and high temperature and high salinity reservoir.In the process of development,in order to ensure safety,the oxygen reduction limits should be controlled fewer than 10%,while oxygen-reduced air can obviously reduce the corrosion rate of pipes;The surface pipelines and injection wells don’t need to consider about oxygen corrosion with no water,special materials and structure of pipe or corrosion inhibitor can be applied to the surface pipelines and injection wellbores with water.Air/oxygen-reduced air is a low-cost displacement medium and it could be applied in many special conditions of low permeability reservoir for energy supplement,huff and puff and displacement,that means oxygen-reduced air flooding has become the most potential strategic technology in 20 years.
