Hampered by the ambiguous mechanism of hydrogen evolution reaction(HER)in basic media,the exploration of highly efficient catalytically active sites for alkaline HER is of significance.Herein,a metal oxide Sr_(4)Ru_(2...Hampered by the ambiguous mechanism of hydrogen evolution reaction(HER)in basic media,the exploration of highly efficient catalytically active sites for alkaline HER is of significance.Herein,a metal oxide Sr_(4)Ru_(2)O_(9)engineering a face-sharing[RuO_(6)]octahedra motif was synthesized through the solid-state method,and served as HER electrocatalyst.Benefited from the Ru-Ru metallic bonding crossing the common plane,the H*adsorption and reaction energy barriers were optimized.Sr_(4)Ru_(2)O_(9)only required an ultra-small overpotential(η10)of 28 m V at a current density of 10 mA cm^(-2) for HER in 1.0 M KOH with an exceptional stability(180 hours),outperforming the commercial Pt/C(η10=38 mV).These findings suggest a fresh insight in designing novel active sites for electrocatalysis.展开更多
A novel two-phase approach towards the corrosion of PtNil0 nanoctahedra has been developed. In this strategy, the active component of Ni in oil-soluble PtNil0 nanoctahedra which resided in the upper toluene phase, suf...A novel two-phase approach towards the corrosion of PtNil0 nanoctahedra has been developed. In this strategy, the active component of Ni in oil-soluble PtNil0 nanoctahedra which resided in the upper toluene phase, suffered from etching and was then transferred into a lower aqueous phase with coordination by ethylenediaminetetraacetate （EDTA）. Due to the existence of the phase-transfer interface promoted by EDTA, the corrosion reaction proceeded at an accelerated rate under the mild conditions. Specifically, the resultant products of octahedral Pt4Ni nanoframes were successfully fabricated for the first time, and PtNi4 porous octahedra could be obtained when the dosage of EDTA-2Na was reduced. After a systematic study of this two-phase system, a ＂synergetic corrosion＂ mechanism is proposed to account for the formation of octahedral Pt4Ni nanoframes, involving contributions from many species （i.e., O2, H2O, H＋, OAm, and EDTA^4-）. As a result of the fascinating three-dimensional geometry of Pt4Ni nanoframes and PtNi4 porous octahedra, both of the corroded nanocrystals showed superior activity over the pristine PtNi^o nanoctahedra for ethanol electrooxidation in alkaline media and hydrogenation of nitrobenzene.展开更多
Controllable synthesis of uniform and single-crystalline CdMoO4 nano-octahedra has been successfully realized at large-scale by a facile reverse-microemulsion route at room temperature. The structures, compositions an...Controllable synthesis of uniform and single-crystalline CdMoO4 nano-octahedra has been successfully realized at large-scale by a facile reverse-microemulsion route at room temperature. The structures, compositions and morphologies of the as-prepared products were characterized in detail by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), respectively. According to the thermochemical cycle, the relationship between the standard molar enthalpy of formation of nano-CdMoO4 and bulk CdMoO4 was proposed for the first time. In combination with micro-calorimetry, the standard molar enthalpies of formation at 298.15 K of as-ynthesized CdMoO4 nano-octahedra were ob-tained.展开更多
Oxygen vacancies have a profound effect on the magnetic,electronic,and transport properties of transition metal oxides but little is known about their effect on thermal expansion.Herein we report the effect of oxygen ...Oxygen vacancies have a profound effect on the magnetic,electronic,and transport properties of transition metal oxides but little is known about their effect on thermal expansion.Herein we report the effect of oxygen defects on the structure formation and thermal expansion properties of the layered perovskite Ca2RuO4(CRO).It is shown that the CRO containing excess oxygen crystallizes in a metallic L-CRO phase without structure transition from 100 K to 500 K and displays a normal thermal expansion behavior,whereas those with oxygen vacancies adopt at room temperature an insulating S-CRO phase and exhibit an enormous negative thermal expansion(NTE)from 100 K to about 360 K,from where they undergo a structure transition to a high temperature metallic L-CRO phase.Compared to the L-CRO containing excess oxygen,the S-CRO structure has increasingly large orthorhombic strain and distinctive in-plane distortion upon cooling.The in-plane distortion of the RuO6 octahedra reaches a maximum across 260 K and then relaxes monotonically,providing a structure evidence for the appearance of an antiferromagnetic orbital ordering in the paramagnetic phase and the A_g phonon mode suppression and phase flip across the same temperature found recently.Both the L-and S-CRO display an antiferromagnetic ordering at about 150-110 K,with ferromagnetic ordering components at lower temperature.The NTE in S-CRO is a result of a complex interplay among the spin,orbital,and lattice.展开更多
The size and morphology of the Cu2O nanocrystals are crucial to improving the performance of photoelectric devices.In this paper,Cu2O nanocrystals have been deposited onto aluminum substrates.The effect of different a...The size and morphology of the Cu2O nanocrystals are crucial to improving the performance of photoelectric devices.In this paper,Cu2O nanocrystals have been deposited onto aluminum substrates.The effect of different applied potentials on the chemical composition,morphology and grain size has been investigated.Compared with previous work,it has been found that the potentials have strong effect on particle size,while the morphology changes only when the potentials over-0.5 V,but no other compositions such as CuO or Cu exist in the products,which could clarify the formation mechanism of the Cu2O nanocrystals.展开更多
Infrared(IR)birefringent materials with large optical anisotropy and wide transparency range are important for efficient light manipulation in various IR optical devices.Herein,two new IR birefringent materials AMgGeS...Infrared(IR)birefringent materials with large optical anisotropy and wide transparency range are important for efficient light manipulation in various IR optical devices.Herein,two new IR birefringent materials AMgGeSe_(3)(A=Li,Na)with large optical anisotropy were rationally designed by a rigid octahedron and flexible dimer combined strategy and fabricated in experiment.The introduction of rigid[LiSe_(6)]/[NaSe_(6)]and[MgSe_(6)]octahedra effectively regulates the geometry and arrangement of the flexible[Ge2Se6]dimers,resulting in the birefringence as large as 0.334@1,064 nm in LiMgGeSe_(3) and 0.445@1,064 nm(the largest one in the reported[Ge_(2)Se_(6)]dimer-contained selenides)in NaMgGeSe_(3).Density functional theory(DFT)calculations and statistical analyses highlight the influence of polarizability anisotropy,density,arrangement of units,as well as layer distance on birefringence.The results indicate that AMgGeSe_(3)(A=Li,Na)crystals are the promising IR birefringent materials and it gives an insight into the exploration of new IR birefringent materials with large birefringence based on the clamping effect from rigid groups.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(2020XZZX002-07)supported by Natural Science Foundation of Zhejiang Province(No.LR17B060003)the National Natural Science Foundation of China(Project Nos.21776248 and 21676246)。
文摘Hampered by the ambiguous mechanism of hydrogen evolution reaction(HER)in basic media,the exploration of highly efficient catalytically active sites for alkaline HER is of significance.Herein,a metal oxide Sr_(4)Ru_(2)O_(9)engineering a face-sharing[RuO_(6)]octahedra motif was synthesized through the solid-state method,and served as HER electrocatalyst.Benefited from the Ru-Ru metallic bonding crossing the common plane,the H*adsorption and reaction energy barriers were optimized.Sr_(4)Ru_(2)O_(9)only required an ultra-small overpotential(η10)of 28 m V at a current density of 10 mA cm^(-2) for HER in 1.0 M KOH with an exceptional stability(180 hours),outperforming the commercial Pt/C(η10=38 mV).These findings suggest a fresh insight in designing novel active sites for electrocatalysis.
文摘A novel two-phase approach towards the corrosion of PtNil0 nanoctahedra has been developed. In this strategy, the active component of Ni in oil-soluble PtNil0 nanoctahedra which resided in the upper toluene phase, suffered from etching and was then transferred into a lower aqueous phase with coordination by ethylenediaminetetraacetate （EDTA）. Due to the existence of the phase-transfer interface promoted by EDTA, the corrosion reaction proceeded at an accelerated rate under the mild conditions. Specifically, the resultant products of octahedral Pt4Ni nanoframes were successfully fabricated for the first time, and PtNi4 porous octahedra could be obtained when the dosage of EDTA-2Na was reduced. After a systematic study of this two-phase system, a ＂synergetic corrosion＂ mechanism is proposed to account for the formation of octahedral Pt4Ni nanoframes, involving contributions from many species （i.e., O2, H2O, H＋, OAm, and EDTA^4-）. As a result of the fascinating three-dimensional geometry of Pt4Ni nanoframes and PtNi4 porous octahedra, both of the corroded nanocrystals showed superior activity over the pristine PtNi^o nanoctahedra for ethanol electrooxidation in alkaline media and hydrogenation of nitrobenzene.
基金supported by the National Natural Science Foundation of China (20963001, 21273050)Guangxi Natural Science Foundation(0991001z)
文摘Controllable synthesis of uniform and single-crystalline CdMoO4 nano-octahedra has been successfully realized at large-scale by a facile reverse-microemulsion route at room temperature. The structures, compositions and morphologies of the as-prepared products were characterized in detail by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), respectively. According to the thermochemical cycle, the relationship between the standard molar enthalpy of formation of nano-CdMoO4 and bulk CdMoO4 was proposed for the first time. In combination with micro-calorimetry, the standard molar enthalpies of formation at 298.15 K of as-ynthesized CdMoO4 nano-octahedra were ob-tained.
基金the National Natural Science Foundation of China(Grant Nos.11874328 and 11574276)The SXRD experiments were performed at the BL02B2 and BL04B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute(JASRI+1 种基金proposal Nos.2019A1167,2019A1095,and 2019A1340)We also acknowledge the help of Beamline Scientists Dr.Lirong Zheng(BSRF),Dr.Shogo Kawaguchi,and Dr.Koji Ohara(SPring-8).
文摘Oxygen vacancies have a profound effect on the magnetic,electronic,and transport properties of transition metal oxides but little is known about their effect on thermal expansion.Herein we report the effect of oxygen defects on the structure formation and thermal expansion properties of the layered perovskite Ca2RuO4(CRO).It is shown that the CRO containing excess oxygen crystallizes in a metallic L-CRO phase without structure transition from 100 K to 500 K and displays a normal thermal expansion behavior,whereas those with oxygen vacancies adopt at room temperature an insulating S-CRO phase and exhibit an enormous negative thermal expansion(NTE)from 100 K to about 360 K,from where they undergo a structure transition to a high temperature metallic L-CRO phase.Compared to the L-CRO containing excess oxygen,the S-CRO structure has increasingly large orthorhombic strain and distinctive in-plane distortion upon cooling.The in-plane distortion of the RuO6 octahedra reaches a maximum across 260 K and then relaxes monotonically,providing a structure evidence for the appearance of an antiferromagnetic orbital ordering in the paramagnetic phase and the A_g phonon mode suppression and phase flip across the same temperature found recently.Both the L-and S-CRO display an antiferromagnetic ordering at about 150-110 K,with ferromagnetic ordering components at lower temperature.The NTE in S-CRO is a result of a complex interplay among the spin,orbital,and lattice.
文摘The size and morphology of the Cu2O nanocrystals are crucial to improving the performance of photoelectric devices.In this paper,Cu2O nanocrystals have been deposited onto aluminum substrates.The effect of different applied potentials on the chemical composition,morphology and grain size has been investigated.Compared with previous work,it has been found that the potentials have strong effect on particle size,while the morphology changes only when the potentials over-0.5 V,but no other compositions such as CuO or Cu exist in the products,which could clarify the formation mechanism of the Cu2O nanocrystals.
基金supported by the High-level Talent Project of Xinjiang Uygur Autonomous Region(2020000039)the National Natural Science Foundation of China(52002398,61835014,51972336)the Xinjiang Key Laboratory of Electronic Information Materials and Devices(2017D04029)。
文摘Infrared(IR)birefringent materials with large optical anisotropy and wide transparency range are important for efficient light manipulation in various IR optical devices.Herein,two new IR birefringent materials AMgGeSe_(3)(A=Li,Na)with large optical anisotropy were rationally designed by a rigid octahedron and flexible dimer combined strategy and fabricated in experiment.The introduction of rigid[LiSe_(6)]/[NaSe_(6)]and[MgSe_(6)]octahedra effectively regulates the geometry and arrangement of the flexible[Ge2Se6]dimers,resulting in the birefringence as large as 0.334@1,064 nm in LiMgGeSe_(3) and 0.445@1,064 nm(the largest one in the reported[Ge_(2)Se_(6)]dimer-contained selenides)in NaMgGeSe_(3).Density functional theory(DFT)calculations and statistical analyses highlight the influence of polarizability anisotropy,density,arrangement of units,as well as layer distance on birefringence.The results indicate that AMgGeSe_(3)(A=Li,Na)crystals are the promising IR birefringent materials and it gives an insight into the exploration of new IR birefringent materials with large birefringence based on the clamping effect from rigid groups.
基金This work was financially supported by the start-up funding from Soochow University,Peking University,and Thousand Youth Talent Program,the National Natural Science Foundation of China (No.21571135),and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
