The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surroga...The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surrogate.Based on a previous investigation of discharge properties,product distribution and energy efficiency,the operating parameters such as CH4 concentration,applied voltage and gas flow rate can effectively affect the CH4 conversion rate,the selectivity of H2 and the properties of solid generated carbon.Nevertheless,the basic properties of RGA plasma and its role in CH4 conversion are scarcely mentioned.In the present work,a 3D RGA model,with a detailed nonequilibrium CH4/Ar plasma chemistry,is developed to validate the previous experiments on CBM conversion,aiming in particular at the distribution of H2 and other gas products.Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection,electron migration and electron diffusion,and is prominently determined by the variation of the gas flow rate and applied voltage.Subsequently,a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction,taking into consideration the formation and loss pathways of crucial targeted substances(such as CH4,C2H2,H2 and H radicals)and corresponding contribution rates.Additionally,the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy(SEM)and Raman spectroscopy.The results show that increasing the applied voltage and decreasing CH4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets,while the size of the graphene sheets is slightly affected by the change in gas flow rate.展开更多
In the last decade,integrated computation of corrosion has made significant progress towards the atomic-scale clarification of corrosion mechanisms and computer-aided designing of advanced materials with excellent cor...In the last decade,integrated computation of corrosion has made significant progress towards the atomic-scale clarification of corrosion mechanisms and computer-aided designing of advanced materials with excellent corrosion resistance.This review focuses on the theoretical calculation methods and developing tendency in corrosion study,and three specific applications are presented.First-principle techniques combined with molecular dynamics method,peridynamic theory and finite element method provide multiscale models to investigate micromechanisms of stress corrosion cracking and hydrogen-induced cracking.Calculations of passivity and passive film breakdown are elaborated through point defects diffusion and its correlation of the energy level degeneracy.By surveying publications,the artificial intelligence technology is pointed out how the computer can pave the way of predicting corrosion degrees as well as designing new corrosion resistant materials.To get better and efficient development of integrated computation of corrosion,extensive cooperation and powerful data infrastructure are needed by stronger collaboration in the future.展开更多
基金supported by the Foundation for Innovative Research Groups of National Natural Science Foundation of China (No. 51621005)China Postdoctoral Science Foundation (No. 2018M630672)
文摘The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surrogate.Based on a previous investigation of discharge properties,product distribution and energy efficiency,the operating parameters such as CH4 concentration,applied voltage and gas flow rate can effectively affect the CH4 conversion rate,the selectivity of H2 and the properties of solid generated carbon.Nevertheless,the basic properties of RGA plasma and its role in CH4 conversion are scarcely mentioned.In the present work,a 3D RGA model,with a detailed nonequilibrium CH4/Ar plasma chemistry,is developed to validate the previous experiments on CBM conversion,aiming in particular at the distribution of H2 and other gas products.Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection,electron migration and electron diffusion,and is prominently determined by the variation of the gas flow rate and applied voltage.Subsequently,a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction,taking into consideration the formation and loss pathways of crucial targeted substances(such as CH4,C2H2,H2 and H radicals)and corresponding contribution rates.Additionally,the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy(SEM)and Raman spectroscopy.The results show that increasing the applied voltage and decreasing CH4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets,while the size of the graphene sheets is slightly affected by the change in gas flow rate.
基金the financial support from the National Key Research and Development Program of China(No.2017YFB 0702300)the National Natural Science Foundation of China(No.51871028)the Fundamental Research Funds for the Central Universities(No.FRF-TP-19-003B2)
文摘In the last decade,integrated computation of corrosion has made significant progress towards the atomic-scale clarification of corrosion mechanisms and computer-aided designing of advanced materials with excellent corrosion resistance.This review focuses on the theoretical calculation methods and developing tendency in corrosion study,and three specific applications are presented.First-principle techniques combined with molecular dynamics method,peridynamic theory and finite element method provide multiscale models to investigate micromechanisms of stress corrosion cracking and hydrogen-induced cracking.Calculations of passivity and passive film breakdown are elaborated through point defects diffusion and its correlation of the energy level degeneracy.By surveying publications,the artificial intelligence technology is pointed out how the computer can pave the way of predicting corrosion degrees as well as designing new corrosion resistant materials.To get better and efficient development of integrated computation of corrosion,extensive cooperation and powerful data infrastructure are needed by stronger collaboration in the future.
