Reduced graphene oxide(rGO)aerogels are emerging as very attractive scaffolds for high-performance electromagnetic wave absorption materials(EWAMs)due to their intrinsic conductive networks and intricate interior micr...Reduced graphene oxide(rGO)aerogels are emerging as very attractive scaffolds for high-performance electromagnetic wave absorption materials(EWAMs)due to their intrinsic conductive networks and intricate interior microstructure,as well as good compatibility with other electromagnetic(EM)components.Herein,we realized the decoration of rGO aerogel with Mo_(2)C nanoparticles by sequential hydrothermal assembly,freeze-drying,and high-temperature pyrolysis.Results show that Mo_(2)C nanoparticle loading can be easily controlled by the ammonium molybdate to glucose molar ratio.The hydrophobicity and thermal insulation of the rGO aerogel are effectively improved upon the introduction of Mo_(2)C nanoparticles,and more importantly,these nanoparticles regulate the EM properties of the rGO aerogel to a large extent.Although more Mo_(2)C nanoparticles may decrease the overall attenuation ability of the rGO aerogel,they bring much better impedance matching.At a molar ratio of 1:1,a desirable balance between attenuation ability and impedance matching is observed.In this context,the Mo_(2)C/r GO aerogel displays strong reflection loss and broad response bandwidth,even with a small applied thickness(1.7 mm)and low filler loading(9.0wt%).The positive effects of Mo_(2)C nanoparticles on multifunctional properties may render Mo_(2)C/r GO aerogels promising candidates for high-performance EWAMs under harsh conditions.展开更多
The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S) batteries.Herein, we...The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S) batteries.Herein, we develop a facile "in-situ growth" method to decorate ultra-small Mo2 C nanoparticles(USMo2 C) on the surface of Ketjen Black(KB) to functionalize the commercial polypropylene(PP) separators,which can accelerate the redox kinetics of lithium polysulfides conversion and effectively increase the utilization of sulfur for Li-S batteries. Importantly, the US-Mo2 C nanoparticles have abundant sites for chemical adsorption towards polysulfides and the conductive carbon networks of KB have cross-linked pore channels, which can promote electron transport and provide physical barrier and volume expansion space for polysulfides. Due to the combined effects of the US-Mo2 C and KB, Li-S cells employing the multifunctional PP separators modified with KB/US-Mo2 C composite(KB/US-Mo2 C@PP) exhibit a high specific capacity(1212.8 mAh g^(-1) at 0.2 C), and maintain a reversible capacity of 1053.3 m Ah g^(-1) after 100 cycles.More importantly, the KB/US-Mo2 C@PP cells with higher sulfur mass loading of 4.9 mg cm^(-2) have superb areal capacity of 2.3 mAh cm^(-2). This work offers a novel and promising perspective for high-performance Li-S batteries from both the shuttle effect and the complex polysulfides conversion.展开更多
The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-...The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.展开更多
We report the microwave synthesis and the doping effect of Mo_(3-)xRe_xAl_(2)C(0≤x≤0.3)superconductor.Re doping into Mo_(3)Al_(2)C results in a regular shrinkage of the lattice,marked by the linear decrease of latti...We report the microwave synthesis and the doping effect of Mo_(3-)xRe_xAl_(2)C(0≤x≤0.3)superconductor.Re doping into Mo_(3)Al_(2)C results in a regular shrinkage of the lattice,marked by the linear decrease of lattice parameter a from6.868(1)A(for Mo_(3)Al_(2)C)to 6.846(2)A(for Mo_(2.7)Re_(0.3)Al_(2)C).Upon Re doping,T_(c)of Mo_(3-x)Re_xAl_(2)C first increases and then decreases,with the maximum T_(c)=9.14 K at the optimal doping level of x=0.09.Our report provides a convenient method to synthesize Mo_(3-)xRe_xAl_(2)C within minutes,and also marks the first Re doping study with enhanced superconductivity on the non-centrosymmetric superconductor Mo_(3)Al_(2)C.展开更多
Hydrogen is recognized as a promising energy scours in the close future.Online hydrogen preparation from formic acid under mild reaction conditions causes extensive interests.Mo_(2)C and metal(Fe,Ni,Co,K)doped Mo_(2)C...Hydrogen is recognized as a promising energy scours in the close future.Online hydrogen preparation from formic acid under mild reaction conditions causes extensive interests.Mo_(2)C and metal(Fe,Ni,Co,K)doped Mo_(2)C on granular activated carbon(GAC)were prepared and used as heterogeneous catalysts for H2 generation from formic acid on a fixed bed reactor at 100–250°C.The formic acid conversions on doped Mo_(2)C-Me/GAC are clearly improved,especially at lower reaction temperatures.Co doping presents outstanding effect on H2 selectivity and conversion rate compared to Ni and Fe.A 56.3%formic acid conversion was reached on Mo_(2)C-Co/GAC at 100°C,which triples that on Mo_(2)C/GAC at the same temperature.At 150°C,a high formic acid conversion over 90%was reached on Mo_(2)C-Co/GAC.These long lifetime catalysts with no precious metal provide a low cost route to hydrogen production from formic acid.展开更多
基金supported by the China Postdoctoral Science Foundation(No.2021MD703944)the Fund of Science and Technology on Near-Surface Detection Laboratory(No.6142414211808)+1 种基金the Director Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2021ZR06)the National Natural Science Foundation of China(No.21776053)。
文摘Reduced graphene oxide(rGO)aerogels are emerging as very attractive scaffolds for high-performance electromagnetic wave absorption materials(EWAMs)due to their intrinsic conductive networks and intricate interior microstructure,as well as good compatibility with other electromagnetic(EM)components.Herein,we realized the decoration of rGO aerogel with Mo_(2)C nanoparticles by sequential hydrothermal assembly,freeze-drying,and high-temperature pyrolysis.Results show that Mo_(2)C nanoparticle loading can be easily controlled by the ammonium molybdate to glucose molar ratio.The hydrophobicity and thermal insulation of the rGO aerogel are effectively improved upon the introduction of Mo_(2)C nanoparticles,and more importantly,these nanoparticles regulate the EM properties of the rGO aerogel to a large extent.Although more Mo_(2)C nanoparticles may decrease the overall attenuation ability of the rGO aerogel,they bring much better impedance matching.At a molar ratio of 1:1,a desirable balance between attenuation ability and impedance matching is observed.In this context,the Mo_(2)C/r GO aerogel displays strong reflection loss and broad response bandwidth,even with a small applied thickness(1.7 mm)and low filler loading(9.0wt%).The positive effects of Mo_(2)C nanoparticles on multifunctional properties may render Mo_(2)C/r GO aerogels promising candidates for high-performance EWAMs under harsh conditions.
基金financially supported by the National Natural Science Foundation of China for Innovative Research Groups (No. 51621002)the National Key Research and Development Program of China (Grant No. 2016YFA0203700)+5 种基金NSFC (Grant No 51672083)Program of Shanghai Academic/Technology Research Leader (18XD1401400)Basic Research Program of Shanghai (17JC1404702)Leading talents in Shanghai in 2018The Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, the 111 project (B14018)The Fundamental Research Funds for Central Universities (222201718002)。
文摘The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S) batteries.Herein, we develop a facile "in-situ growth" method to decorate ultra-small Mo2 C nanoparticles(USMo2 C) on the surface of Ketjen Black(KB) to functionalize the commercial polypropylene(PP) separators,which can accelerate the redox kinetics of lithium polysulfides conversion and effectively increase the utilization of sulfur for Li-S batteries. Importantly, the US-Mo2 C nanoparticles have abundant sites for chemical adsorption towards polysulfides and the conductive carbon networks of KB have cross-linked pore channels, which can promote electron transport and provide physical barrier and volume expansion space for polysulfides. Due to the combined effects of the US-Mo2 C and KB, Li-S cells employing the multifunctional PP separators modified with KB/US-Mo2 C composite(KB/US-Mo2 C@PP) exhibit a high specific capacity(1212.8 mAh g^(-1) at 0.2 C), and maintain a reversible capacity of 1053.3 m Ah g^(-1) after 100 cycles.More importantly, the KB/US-Mo2 C@PP cells with higher sulfur mass loading of 4.9 mg cm^(-2) have superb areal capacity of 2.3 mAh cm^(-2). This work offers a novel and promising perspective for high-performance Li-S batteries from both the shuttle effect and the complex polysulfides conversion.
基金financially supported by the National Natural Science Foundation of China(21972099)the Application Foundation Program of Sichuan Province(2021YJ0305)+1 种基金the 111 project(B17030).Shanghai Synchrotron Radiation Facility(SSRF)for XAS experiments and the support by the project from NPL of CAEP(2019BB08)。
文摘The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.
基金the National Key Research and Development of China(Grant Nos.2018YFA0704200 and 2016YFA0300301)the National Natural Science Foundation of China(Grant Nos.12074414 and 11774402)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB25000000)。
文摘We report the microwave synthesis and the doping effect of Mo_(3-)xRe_xAl_(2)C(0≤x≤0.3)superconductor.Re doping into Mo_(3)Al_(2)C results in a regular shrinkage of the lattice,marked by the linear decrease of lattice parameter a from6.868(1)A(for Mo_(3)Al_(2)C)to 6.846(2)A(for Mo_(2.7)Re_(0.3)Al_(2)C).Upon Re doping,T_(c)of Mo_(3-x)Re_xAl_(2)C first increases and then decreases,with the maximum T_(c)=9.14 K at the optimal doping level of x=0.09.Our report provides a convenient method to synthesize Mo_(3-)xRe_xAl_(2)C within minutes,and also marks the first Re doping study with enhanced superconductivity on the non-centrosymmetric superconductor Mo_(3)Al_(2)C.
基金financial support of grant from the Natural Science Funds for Young Scholar of China(Grant No.21107049)the priority academic program development of Jiangsu Higher Education Institution(PAPD).
文摘Hydrogen is recognized as a promising energy scours in the close future.Online hydrogen preparation from formic acid under mild reaction conditions causes extensive interests.Mo_(2)C and metal(Fe,Ni,Co,K)doped Mo_(2)C on granular activated carbon(GAC)were prepared and used as heterogeneous catalysts for H2 generation from formic acid on a fixed bed reactor at 100–250°C.The formic acid conversions on doped Mo_(2)C-Me/GAC are clearly improved,especially at lower reaction temperatures.Co doping presents outstanding effect on H2 selectivity and conversion rate compared to Ni and Fe.A 56.3%formic acid conversion was reached on Mo_(2)C-Co/GAC at 100°C,which triples that on Mo_(2)C/GAC at the same temperature.At 150°C,a high formic acid conversion over 90%was reached on Mo_(2)C-Co/GAC.These long lifetime catalysts with no precious metal provide a low cost route to hydrogen production from formic acid.
