Titanium-matrix composites have important and wide applications in the transport and aerospace industries. The current research was focused on powder metallurgy processing of in-situ reinforced titanium-matrix composi...Titanium-matrix composites have important and wide applications in the transport and aerospace industries. The current research was focused on powder metallurgy processing of in-situ reinforced titanium-matrix composite with Ti B whiskers. The Ti-6Al-4V alloy and B4 C additive powders were used as raw materials. Two different consolidation techniques, namely press-and-sintering and spark plasma sintering, were selected. It was observed that in-situ Ti B whiskers were formed during sintering in both methods. The changes in size, aspect ratio and distribution of in-situ whiskers in different composite samples were monitored. The effect of spark plasma sintering temperature on the synthesis of in-situ whiskers was also investigated. Based on the microstructural observations（optical microscopy and scanning electron microscopy） and the energy dispersive spectroscopy analysis, it was concluded that increasing the spark plasma sintering temperature from 900 to 1100 °C would lead to the complete formation of in-situ Ti B whiskers and reduced porosity content.展开更多
Tandem electrocatalysis is an emerging concept for effective electrochemical CO_(2) reduction reaction(CO_(2)RR)towards multicarbons(C_(2+)).This decouples the multiple steps of CO_(2)-to-C_(2+)into two steps of CO_(2...Tandem electrocatalysis is an emerging concept for effective electrochemical CO_(2) reduction reaction(CO_(2)RR)towards multicarbons(C_(2+)).This decouples the multiple steps of CO_(2)-to-C_(2+)into two steps of CO_(2)-to-CO and CO-to-C_(2+)catalyzed by individual catalysts,to improve the Faradic efficiency(FE).However,due to the mass-transport limitation of CO from the generation site to the long-distance consumption site,such a strategy still remains challenge for high-rate production of C_(2+)products.Herein,we designed CuO/Ni single atoms tandem catalyst,which made the catalytic sites of Ni and Cu for independently catalyzing CO_(2)-to-CO and CO-to-C_(2+)compactly neighbored,enabling the in-situ generation and rapid consumption of CO.The CuO/Ni SAs tandem catalyst achieved a particularly high partial current density of C_(2+)products(1220.8 mA/cm^(2)),while still maintained outstanding C_(2+)products FE(81.4%)and excellent selectivities towards ethylene(FE 54.1%)and ethanol(FE 28.8%),enabling the profitable production of multicarbons by CO_(2)RR.展开更多
The hydrogen evolution reaction(HER)as a fundamental process in electrocatalysis plays a significant role in clean energy technologies.For an energy-efficient HER,it demands an effective,durable,and low-cost catalyst ...The hydrogen evolution reaction(HER)as a fundamental process in electrocatalysis plays a significant role in clean energy technologies.For an energy-efficient HER,it demands an effective,durable,and low-cost catalyst to trigger proton reduction with minimal overpotential and fast kinetics.Here,we successfully fabricate a highly efficient HER catalyst of N-C/Co/Mo_(2)C holey nanorods with Co/b-Mo_(2)C nanoparticles uniformly embedded in nitrogen-doped carbon(N-C/Co/Mo_(2)C)by pyrolyzing the molybdate-coordinated zeolitic imidazolate framework(ZIF-67/MoO_(4)^(2-))holey nanorods,which result from the reaction between CoMoO_(4)and Me IM in a methanol/water/triethylamine mixed solution.The uniform distribution of MoO_(4)^(2-)in the ZIF-67/MoO_(4)^(2-)enables Co/β-Mo_(2)C nanoparticles to be welldistributed within nitrogen-doped carbon holey nanorods.This synthetic strategy endows the N-C/Co/Mo_(2)C catalyst with uniformly decorated bimetal,thus attaining excellent HER electrocatalytic activities with a small overpotential of 142.0 m V at 10 m A cm^(-2)and superior stability in 1.0 mol L^(-1)KOH aqueous solution.展开更多
文摘Titanium-matrix composites have important and wide applications in the transport and aerospace industries. The current research was focused on powder metallurgy processing of in-situ reinforced titanium-matrix composite with Ti B whiskers. The Ti-6Al-4V alloy and B4 C additive powders were used as raw materials. Two different consolidation techniques, namely press-and-sintering and spark plasma sintering, were selected. It was observed that in-situ Ti B whiskers were formed during sintering in both methods. The changes in size, aspect ratio and distribution of in-situ whiskers in different composite samples were monitored. The effect of spark plasma sintering temperature on the synthesis of in-situ whiskers was also investigated. Based on the microstructural observations（optical microscopy and scanning electron microscopy） and the energy dispersive spectroscopy analysis, it was concluded that increasing the spark plasma sintering temperature from 900 to 1100 °C would lead to the complete formation of in-situ Ti B whiskers and reduced porosity content.
基金supported by the National Key R&D Program of China(2020YFA0710200)the DNL Cooperation Fund,Chinese Academy of Sciences(DNL201918)+6 种基金the Fundamental Research Funds for the Central Universities(WK2060000004,WK2060000021,WK2060000025,KY2060000180,and KY2060000195)the National Natural Science Foundation of China(21805191)Pengcheng Scholar Program,China Postdoctoral Science Foundation(2019M653004)Shenzhen Peacock Plan(KQTD2016053112042971)Shenzhen Science and Technology Program(JCYJ20190808142001745,JCYJ20200812160737002,and RCJC20200714114434086)Guangdong Basic and Applied Basic Research Foundation(2020A1515010982)Shenzhen Stable Support Project(20200812122947002)。
文摘Tandem electrocatalysis is an emerging concept for effective electrochemical CO_(2) reduction reaction(CO_(2)RR)towards multicarbons(C_(2+)).This decouples the multiple steps of CO_(2)-to-C_(2+)into two steps of CO_(2)-to-CO and CO-to-C_(2+)catalyzed by individual catalysts,to improve the Faradic efficiency(FE).However,due to the mass-transport limitation of CO from the generation site to the long-distance consumption site,such a strategy still remains challenge for high-rate production of C_(2+)products.Herein,we designed CuO/Ni single atoms tandem catalyst,which made the catalytic sites of Ni and Cu for independently catalyzing CO_(2)-to-CO and CO-to-C_(2+)compactly neighbored,enabling the in-situ generation and rapid consumption of CO.The CuO/Ni SAs tandem catalyst achieved a particularly high partial current density of C_(2+)products(1220.8 mA/cm^(2)),while still maintained outstanding C_(2+)products FE(81.4%)and excellent selectivities towards ethylene(FE 54.1%)and ethanol(FE 28.8%),enabling the profitable production of multicarbons by CO_(2)RR.
基金National Institute of Advanced Industrial Science and Technology(AIST)the Japan Society for the Promotion of Science(JSPS)for financial support。
文摘The hydrogen evolution reaction(HER)as a fundamental process in electrocatalysis plays a significant role in clean energy technologies.For an energy-efficient HER,it demands an effective,durable,and low-cost catalyst to trigger proton reduction with minimal overpotential and fast kinetics.Here,we successfully fabricate a highly efficient HER catalyst of N-C/Co/Mo_(2)C holey nanorods with Co/b-Mo_(2)C nanoparticles uniformly embedded in nitrogen-doped carbon(N-C/Co/Mo_(2)C)by pyrolyzing the molybdate-coordinated zeolitic imidazolate framework(ZIF-67/MoO_(4)^(2-))holey nanorods,which result from the reaction between CoMoO_(4)and Me IM in a methanol/water/triethylamine mixed solution.The uniform distribution of MoO_(4)^(2-)in the ZIF-67/MoO_(4)^(2-)enables Co/β-Mo_(2)C nanoparticles to be welldistributed within nitrogen-doped carbon holey nanorods.This synthetic strategy endows the N-C/Co/Mo_(2)C catalyst with uniformly decorated bimetal,thus attaining excellent HER electrocatalytic activities with a small overpotential of 142.0 m V at 10 m A cm^(-2)and superior stability in 1.0 mol L^(-1)KOH aqueous solution.
