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
为了提高ZnSnO3的氢敏性能,以共沉淀法制备ZnSnO3并对其进行了贵金属Pd2+掺杂.采用X射线衍射仪(X-ray diffraction,XRD)及透射电镜(transmission electron microscopy,TEM)对制备的气敏材料进行结构及形貌表征,并使用静态配气法测试了...为了提高ZnSnO3的氢敏性能,以共沉淀法制备ZnSnO3并对其进行了贵金属Pd2+掺杂.采用X射线衍射仪(X-ray diffraction,XRD)及透射电镜(transmission electron microscopy,TEM)对制备的气敏材料进行结构及形貌表征,并使用静态配气法测试了掺杂前后ZnSnO3的氢敏性能.结果表明:掺杂Pd2+可显著提高ZnSnO3的氢敏性能.在工作温度为240℃、浓度为300×10-6的条件下,Pd2+掺杂纳米ZnSnO3对氢气的灵敏度为12,是未掺杂时的3倍.基于第一性原理探讨气敏机理,计算结果表明:Pd2+掺杂改变了ZnSnO3能带间的电子运动状态,使ZnSnO3费米能级由0.725 eV移动到1.035 eV,在费米能级附近产生新的电子峰,使其电导性能在气敏反应过程中改变更为明显.Pd2+掺杂还使ZnSnO3表面吸附氧的能力显著增加,对提高氢敏性能起到了关键作用.展开更多
采用水热法合成层状LiMn1/3Co1/3Ni1/3-xPdxO2（x=0、0.01、0.03和0.05）锂离子电池正极材料,考察Pd2＋掺杂量x对产物结构、形貌和电化学性能的影响。XRD、SEM测试结果表明：掺杂Pd2＋未改变正极材料的结构,但晶胞体积略有增加,x=0.03...采用水热法合成层状LiMn1/3Co1/3Ni1/3-xPdxO2（x=0、0.01、0.03和0.05）锂离子电池正极材料,考察Pd2＋掺杂量x对产物结构、形貌和电化学性能的影响。XRD、SEM测试结果表明：掺杂Pd2＋未改变正极材料的结构,但晶胞体积略有增加,x=0.03的产物,粒径较为均匀。充放电测试结果表明：随着x的增大,首次放电比容量先增大、后减小;x=0.03的产物,以0.1 C在4.3--2.5 V循环,首次放电比容量为174.9 m Ah/g;以2.0 C循环100次,比容量为80.01 m Ah/g,高于未掺杂样品的60.07 m Ah/g。循环伏安和交流阻抗谱测试结果表明：Pd2＋掺杂能提高正极材料的可逆性,改善电化学性能。展开更多
以硝酸铝和尿素为原料,通过水热法成功合成富含五配位Al^(3+)的γ-Al_(2)O_(3)载体,采用XRD、SEM、STEM-HAADF、27Al MAS NMR、N_(2)吸附-脱附等手段表征了载体的物理化学性质,并对采用该载体制备的Pd/Al_(2)O_(3)催化剂进行了蒽醌加氢...以硝酸铝和尿素为原料,通过水热法成功合成富含五配位Al^(3+)的γ-Al_(2)O_(3)载体,采用XRD、SEM、STEM-HAADF、27Al MAS NMR、N_(2)吸附-脱附等手段表征了载体的物理化学性质,并对采用该载体制备的Pd/Al_(2)O_(3)催化剂进行了蒽醌加氢制H_(2)O_(2)的初步性能评价。表征结果显示,合成的载体中的五配位Al^(3+)相对含量可达40.88%(w),微观粒子呈棒状,棒的长度1~4μm,直径0.1~0.3μm,BET比表面积可达494 m^(2)/g;所制备的Pd/Al_(2)O_(3)催化剂中Pd纳米粒子分散良好,平均粒径为3.51 nm,且分布较窄。评价结果表明,该催化剂相对于参比剂具有较高的加氢活性。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.
文摘采用水热法合成层状LiMn1/3Co1/3Ni1/3-xPdxO2（x=0、0.01、0.03和0.05）锂离子电池正极材料,考察Pd2＋掺杂量x对产物结构、形貌和电化学性能的影响。XRD、SEM测试结果表明：掺杂Pd2＋未改变正极材料的结构,但晶胞体积略有增加,x=0.03的产物,粒径较为均匀。充放电测试结果表明：随着x的增大,首次放电比容量先增大、后减小;x=0.03的产物,以0.1 C在4.3--2.5 V循环,首次放电比容量为174.9 m Ah/g;以2.0 C循环100次,比容量为80.01 m Ah/g,高于未掺杂样品的60.07 m Ah/g。循环伏安和交流阻抗谱测试结果表明：Pd2＋掺杂能提高正极材料的可逆性,改善电化学性能。
文摘以硝酸铝和尿素为原料,通过水热法成功合成富含五配位Al^(3+)的γ-Al_(2)O_(3)载体,采用XRD、SEM、STEM-HAADF、27Al MAS NMR、N_(2)吸附-脱附等手段表征了载体的物理化学性质,并对采用该载体制备的Pd/Al_(2)O_(3)催化剂进行了蒽醌加氢制H_(2)O_(2)的初步性能评价。表征结果显示,合成的载体中的五配位Al^(3+)相对含量可达40.88%(w),微观粒子呈棒状,棒的长度1~4μm,直径0.1~0.3μm,BET比表面积可达494 m^(2)/g;所制备的Pd/Al_(2)O_(3)催化剂中Pd纳米粒子分散良好,平均粒径为3.51 nm,且分布较窄。评价结果表明,该催化剂相对于参比剂具有较高的加氢活性。
