The intermetallic compound such as Ni_(2)Si has a brittle nature.Therefore,monolithic intermetallic compounds have not yet been prepared by mechanical downsizing.During mechanical drawing of bulk CuNi_(2)Si alloy at r...The intermetallic compound such as Ni_(2)Si has a brittle nature.Therefore,monolithic intermetallic compounds have not yet been prepared by mechanical downsizing.During mechanical drawing of bulk CuNi_(2)Si alloy at room temperature,we observed more than 400%plastic elongation of hard and brittle Ni_(2)Si intermetallic nano-fibers.The calculation based on the density functional theory reveals that the fully coherent interface induces strain on the intermetallic compound surrounded by the matrix,and lowers the intrinsic stacking fault energy below the level required to break an interatomic bond.The new interface between the Ni_(2)Si intermetallic and Cu matrix formed by the plastic deformation is as stable as the original coherent interface formed by precipitation,and the activation energy of the newly formed interface to slip is similar to that of the Cu matrix.All of these make plastic deformation of brittle Ni_(2)Si intermetallic possible by slip without failure.展开更多
Rh has been widely studied as a catalyst for the promising hydrazine oxidation reaction that can replace oxygen evolution reactions for boosting hydrogen production from hydrazine-containing wastewater.Despite Rh bein...Rh has been widely studied as a catalyst for the promising hydrazine oxidation reaction that can replace oxygen evolution reactions for boosting hydrogen production from hydrazine-containing wastewater.Despite Rh being expensive,only a few studies have examined its electrocatalytic mass activity.Herein,surface-limited cation exchange and electrochemical activation processes are designed to remarkably enhance the mass activity of Rh.Rh atoms were readily replaced at the Ni sites on the surface of NiOOH electrodes by cation exchange,and the resulting RhOOH compounds were activated by the electrochemical reduction process.The cation exchange-derived Rh catalysts exhibited particle sizes not exceeding 2 nm without agglomeration,indicating a decrease in the number of inactive inner Rh atoms.Consequently,an improved mass activity of 30 A mg_(Rh)^(-1)was achieved at 0.4 V versus reversible hydrogen electrode.Furthermore,the two-electrode system employing the same CE-derived Rh electrodes achieved overall hydrazine splitting over 36 h at a stable low voltage.The proposed surface-limited CE process is an effective method for reducing inactive atoms of expensive noble metal catalysts.展开更多
The development of CO_(2)into hydrocarbon fuels has emerged as a green method that could help mitigate global warning.The novel structured photocatalyst is a promising material for use in a photocatalytic and magneto-...The development of CO_(2)into hydrocarbon fuels has emerged as a green method that could help mitigate global warning.The novel structured photocatalyst is a promising material for use in a photocatalytic and magneto-electrochemical method that fosters the reduction of CO_(2)by suppressing the recombination of electron−hole pairs and effectively transferring the electrons to the surface for the chemical reaction of CO_(2)reduction.In our study,we have developed a novel-structured AgCuZnS_(2)–graphene–TiO_(2)to analyze its catalytic activity toward the selective evolution of CO_(2).The selectivity of each nanocomposite substantially enhanced the activity of the AgCuZnS_(2)–graphene–TiO_(2)ternary nanocomposite due to the successful interaction,and the selectivity of the final product was improved to a value 3 times higher than that of the pure AgCuZnS_(2)and 2 times higher than those of AgCuZnS_(2)–graphene and AgCuZnS_(2)–TiO_(2)under ultraviolet(UV)-light(λ=254 nm)irradiation in the photocatalytic process.The electrochemical CO_(2)reduction test was also conducted to analyze the efficacy of the AgCuZnS_(2)–graphene–TiO_(2)when used as a working electrode in laboratory electrochemical cells.The electrochemical process was conducted under different experimental conditions,such as various scan rates(mV·s^(–1)),under UV-light and with a 0.07 T magneticcore.The evolution of CO_(2)substantially improved under UV-light(λ=254 nm)and with 0.07 T magnetic-core treatment;these improvements were attributed to the facts that the UV-light activated the electron-transfer pathway and the magnetic core controlled the pathway of electrontransmission/prevention to protect it from chaotic electron movement.Among all tested nanocomposites,AgCuZnS_(2)–graphene–TiO_(2)absorbed the CO_(2)most strongly and showed the best ability to transfer the electron to reduce the CO_(2)to methanol.We believe that our newly-modeled ternary nanocomposite opens up new opportunities for the evolution of CO_(2)to methanol through an electrochemical and photocatalytic process.展开更多
基金the financial support from the National Research Foundation of Korea(Nos.2020M3D1A2098962,2018R1A5A6075959,2014M3A6B1060886)Technology Innovation Program funded By the Ministry of Trade,Industry&Energy,Korea(No.20010384)+1 种基金Fundamental Research Program of the Korean Institute of Materials Science(No.PNK7730)Cooperative program of Professional Development Consortium for Computational Materials Scientists in IMR,Tohoku University(No.20S0513)。
文摘The intermetallic compound such as Ni_(2)Si has a brittle nature.Therefore,monolithic intermetallic compounds have not yet been prepared by mechanical downsizing.During mechanical drawing of bulk CuNi_(2)Si alloy at room temperature,we observed more than 400%plastic elongation of hard and brittle Ni_(2)Si intermetallic nano-fibers.The calculation based on the density functional theory reveals that the fully coherent interface induces strain on the intermetallic compound surrounded by the matrix,and lowers the intrinsic stacking fault energy below the level required to break an interatomic bond.The new interface between the Ni_(2)Si intermetallic and Cu matrix formed by the plastic deformation is as stable as the original coherent interface formed by precipitation,and the activation energy of the newly formed interface to slip is similar to that of the Cu matrix.All of these make plastic deformation of brittle Ni_(2)Si intermetallic possible by slip without failure.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry ofEducation(2021R1A2C3011870 and 2019R1A6A1A03033215)the Korea Research Fellowship Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(2020H1D3A1A04081323)
文摘Rh has been widely studied as a catalyst for the promising hydrazine oxidation reaction that can replace oxygen evolution reactions for boosting hydrogen production from hydrazine-containing wastewater.Despite Rh being expensive,only a few studies have examined its electrocatalytic mass activity.Herein,surface-limited cation exchange and electrochemical activation processes are designed to remarkably enhance the mass activity of Rh.Rh atoms were readily replaced at the Ni sites on the surface of NiOOH electrodes by cation exchange,and the resulting RhOOH compounds were activated by the electrochemical reduction process.The cation exchange-derived Rh catalysts exhibited particle sizes not exceeding 2 nm without agglomeration,indicating a decrease in the number of inactive inner Rh atoms.Consequently,an improved mass activity of 30 A mg_(Rh)^(-1)was achieved at 0.4 V versus reversible hydrogen electrode.Furthermore,the two-electrode system employing the same CE-derived Rh electrodes achieved overall hydrazine splitting over 36 h at a stable low voltage.The proposed surface-limited CE process is an effective method for reducing inactive atoms of expensive noble metal catalysts.
文摘The development of CO_(2)into hydrocarbon fuels has emerged as a green method that could help mitigate global warning.The novel structured photocatalyst is a promising material for use in a photocatalytic and magneto-electrochemical method that fosters the reduction of CO_(2)by suppressing the recombination of electron−hole pairs and effectively transferring the electrons to the surface for the chemical reaction of CO_(2)reduction.In our study,we have developed a novel-structured AgCuZnS_(2)–graphene–TiO_(2)to analyze its catalytic activity toward the selective evolution of CO_(2).The selectivity of each nanocomposite substantially enhanced the activity of the AgCuZnS_(2)–graphene–TiO_(2)ternary nanocomposite due to the successful interaction,and the selectivity of the final product was improved to a value 3 times higher than that of the pure AgCuZnS_(2)and 2 times higher than those of AgCuZnS_(2)–graphene and AgCuZnS_(2)–TiO_(2)under ultraviolet(UV)-light(λ=254 nm)irradiation in the photocatalytic process.The electrochemical CO_(2)reduction test was also conducted to analyze the efficacy of the AgCuZnS_(2)–graphene–TiO_(2)when used as a working electrode in laboratory electrochemical cells.The electrochemical process was conducted under different experimental conditions,such as various scan rates(mV·s^(–1)),under UV-light and with a 0.07 T magneticcore.The evolution of CO_(2)substantially improved under UV-light(λ=254 nm)and with 0.07 T magnetic-core treatment;these improvements were attributed to the facts that the UV-light activated the electron-transfer pathway and the magnetic core controlled the pathway of electrontransmission/prevention to protect it from chaotic electron movement.Among all tested nanocomposites,AgCuZnS_(2)–graphene–TiO_(2)absorbed the CO_(2)most strongly and showed the best ability to transfer the electron to reduce the CO_(2)to methanol.We believe that our newly-modeled ternary nanocomposite opens up new opportunities for the evolution of CO_(2)to methanol through an electrochemical and photocatalytic process.
