Two-dimensional(2D)materials received large amount of studies because of the enormous potential in basic science and industrial applications.Monolayer Pd2Se3 is a fascinating 2D material that was predicted to possess ...Two-dimensional(2D)materials received large amount of studies because of the enormous potential in basic science and industrial applications.Monolayer Pd2Se3 is a fascinating 2D material that was predicted to possess excellent thermoelectric,electronic,transport,and optical properties.However,the fabrication of large-scale and high-quality monolayer Pd2Se3 is still challenging.Here,we report the synthesis of large-scale and high-quality monolayer Pd2Se3 on graphene-SiC(0001)by a two-step epitaxial growth.The atomic structure of Pd2Se3 was investigated by scanning tunneling microscope(STM)and confirmed by non-contact atomic force microscope(nc-AFM).Two subgroups of Se atoms have been identified by nc-AFM image in agreement with the theoretically predicted atomic structure.Scanning tunneling spectroscopy(STS)reveals a bandgap of 1.2 eV,suggesting that monolayer Pd2Se3 can be a candidate for photoelectronic applications.The atomic structure and defect levels of a single Se vacancy were also investigated.The spatial distribution of STS near the Se vacancy reveals a highly anisotropic electronic behavior.The two-step epitaxial synthesis and characterization of Pd2Se3 provide a promising platform for future investigations and applications.展开更多
开发了钠焙烧-还原浸出联合工艺从废Pd/Al_(2)O_(3)催化剂中回收Pd和Al_(2)O_(3)。钠化焙烧热力学分析表明,在最佳的Na_(2)O/Al_(2)O_(3)摩尔比和温度下,NaOH、Na_(2)CO_(3)和Na_(2)C2O4均可以与Al_(2)O_(3)完全反应生成Na Al O2。NaOH...开发了钠焙烧-还原浸出联合工艺从废Pd/Al_(2)O_(3)催化剂中回收Pd和Al_(2)O_(3)。钠化焙烧热力学分析表明,在最佳的Na_(2)O/Al_(2)O_(3)摩尔比和温度下,NaOH、Na_(2)CO_(3)和Na_(2)C2O4均可以与Al_(2)O_(3)完全反应生成Na Al O2。NaOH、Na_(2)CO_(3)和Na_(2)C_(2)O_(4)的焙烧渣经水浸后,Al_(2)O_(3)浸出率分别为99.6%、61.0%和55.3%。机械活化-NaOH无水焙烧工艺避免了焙烧渣的固结且可获得较高的Al_(2)O_(3)浸出率。N_(2)H_(4)·H_(2)O还原浸出避免了水浸过程中Pd的溶解损失且催化剂中99.7%的Al_(2)O_(3)被浸出。最终得到Na Al O2浸出液和富钯渣,其中有价的铝和钯可被进一步回收。展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0202300,2018YFA0305800,and 2019YFA0308500)the National Natural Science Foundation of China(Grant Nos.51922011,51872284,and 61888102)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB30000000 and XDB28000000)the Science Fund from University of the Chinese Academy of Sciences.
文摘Two-dimensional(2D)materials received large amount of studies because of the enormous potential in basic science and industrial applications.Monolayer Pd2Se3 is a fascinating 2D material that was predicted to possess excellent thermoelectric,electronic,transport,and optical properties.However,the fabrication of large-scale and high-quality monolayer Pd2Se3 is still challenging.Here,we report the synthesis of large-scale and high-quality monolayer Pd2Se3 on graphene-SiC(0001)by a two-step epitaxial growth.The atomic structure of Pd2Se3 was investigated by scanning tunneling microscope(STM)and confirmed by non-contact atomic force microscope(nc-AFM).Two subgroups of Se atoms have been identified by nc-AFM image in agreement with the theoretically predicted atomic structure.Scanning tunneling spectroscopy(STS)reveals a bandgap of 1.2 eV,suggesting that monolayer Pd2Se3 can be a candidate for photoelectronic applications.The atomic structure and defect levels of a single Se vacancy were also investigated.The spatial distribution of STS near the Se vacancy reveals a highly anisotropic electronic behavior.The two-step epitaxial synthesis and characterization of Pd2Se3 provide a promising platform for future investigations and applications.
基金the financial support from the Science and Technology Plan of Yunnan Province,China(No.2018ZE001)the National Key Research and Development Program of China(No.2018YFE0110200)+1 种基金the Key Research and Development Program of Hunan Province,China(No.2020SK2125)the Science and Technology Plan of Department of Natural Resources of Hunan Province,China(No.2020-21)。
文摘开发了钠焙烧-还原浸出联合工艺从废Pd/Al_(2)O_(3)催化剂中回收Pd和Al_(2)O_(3)。钠化焙烧热力学分析表明,在最佳的Na_(2)O/Al_(2)O_(3)摩尔比和温度下,NaOH、Na_(2)CO_(3)和Na_(2)C2O4均可以与Al_(2)O_(3)完全反应生成Na Al O2。NaOH、Na_(2)CO_(3)和Na_(2)C_(2)O_(4)的焙烧渣经水浸后,Al_(2)O_(3)浸出率分别为99.6%、61.0%和55.3%。机械活化-NaOH无水焙烧工艺避免了焙烧渣的固结且可获得较高的Al_(2)O_(3)浸出率。N_(2)H_(4)·H_(2)O还原浸出避免了水浸过程中Pd的溶解损失且催化剂中99.7%的Al_(2)O_(3)被浸出。最终得到Na Al O2浸出液和富钯渣,其中有价的铝和钯可被进一步回收。
