MoS_2 has attracted attention as a promising hydrogen evolution reaction(HER) catalyst and a supercapacitor electrode material. However, its catalytic activity and capacitive performance are still hindered by its aggr...MoS_2 has attracted attention as a promising hydrogen evolution reaction(HER) catalyst and a supercapacitor electrode material. However, its catalytic activity and capacitive performance are still hindered by its aggregation and poor intrinsic conductivity. Here, hollow rGO sphere-supported ultrathin MoS_2 nanosheet arrays(hrGO@MoS_2) are constructed via a dual-template approach and employed as bifunctional HER catalyst and supercapacitor electrode material. Because of the expanded interlayer spacing in MoS_2 nanosheets and more exposed electroactive S–Mo–S edges, the constructed h-rGO@MoS_2 architectures exhibit enhanced HER performance. Furthermore, benefiting from the synergistic effect of the improved conductivity and boosted specific surface areas(144.9 m^2 g^(-1), ca. 4.6-times that of pristine MoS_2), the h-rGO@MoS_2 architecture shows a high specific capacitance(238 F g^(-1) at a current density of 0.5 A g^(-1)), excellent rate capacitance, and remarkable cycle stability. Our synthesis method may be extended to construct other vertically aligned hollow architectures,which may serve both as efficient HER catalysts and supercapacitor electrodes.展开更多
A facile synthetic approach has been developed to prepare uniform and size-tunable spiky Au@Ag core-shell nan oparticles (NPs) to tailor the localized surface plasm on res onance (LSPR) properties. The gradual assembl...A facile synthetic approach has been developed to prepare uniform and size-tunable spiky Au@Ag core-shell nan oparticles (NPs) to tailor the localized surface plasm on res onance (LSPR) properties. The gradual assembly of small Au nano crystals allows the size of spiky Au NPs to be modulated from tens to several hundreds of nano meters by tuning the concentration of initial Au seeds and Au source;and the thick ness of the Ag shell can be adjusted with stepwise reduction of Ag(l)ions. The LSPR bands of such spiky Au@Ag core-shell NPs resemble those of pure spiky Au NP cores of similar sizes in near-infrared region, and increasing the Ag shell thickness results in a blue shift and broadening of the LSPR band in the n ear-i nfrared regi on. Additi on ally, the spiky Au@Ag core-shell NPs exhibit improved surface-e nhan ced Rama n scattering (SERS) activity as compared to the bare spiky Au NPs and spherical Ag@Au NPs. This work has offered a facile route to synthesize plasmonic metal NPs with LSPR band in 650 to 800 nm that show strong enhancement of localized electromagnetic field, which provides an effective SERS substrate for SERS imaging and detection in biological fluids and tissues.展开更多
The surface topography of noble metal particles is a significant factor in tailoring surface-enhanced Raman scattering （SERS） properties. Here, we present a simple fabrication route to hexagonally arranged arrays of...The surface topography of noble metal particles is a significant factor in tailoring surface-enhanced Raman scattering （SERS） properties. Here, we present a simple fabrication route to hexagonally arranged arrays of surface-roughened urchin- like Ag hemispheres （Ag-HSs） decorated with Ag nanoparticles （Ag-NPs） for highly active and reproducible SERS substrates. The urchin-like Ag-HS arrays are achieved by sputtering Ag onto the top surface of a highly ordered porous anodic aluminum oxide （AAO） template to form ordered arrays of smooth Ag-HSs and then by electrodepositing Ag-NPs onto the surface of each Ag-HS. Owing to the ordered arrangement of the Ag-HSs and the improved surface roughness, the urchin-like hierarchical Ag-HS arrays can provide sufficient and uniform ＂hot spots＂ for reproducible and highly active SERS effects. Using the urchin-like Ag-HS arrays as SERS substrates, 10-7 M dibutyl phthalate （a member of plasticizers family） and 1.5 × 10-5 M PCB-77 （one congener of polychlorinated biphenyl, a notorious class of pollutants） are identified, showing promising potential for these substrates in the rapid recognition of organic pollutants.展开更多
In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phas...In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phase precursor method can achieve uniform mixing of components at the molecular level through multiple complexation reactions,and then realize the carbo/borothermal reduction reaction at a lower temperature to obtain ultrapure HfB2 powders.The as-resulted quasi-spherical HfB2 powders under the optimum conditions(atomic molar ratio M:B:C=1:2.8:10)calcined at 1500°C for 1 h have an average particle size of 205 nm and an oxygen content of 0.097 wt.%.Detailed analysis of the phase evolution of precursors shows that the formation of HfB2 particles is a mass diffusion mode from the external to internal HfO_(2)cores.We reveal that below 1300°C,HfC is not an intermediate product of HfB2 powder during the transition of precursors.Instead,HfC was formed as a by-product at high temperatures in the carbo/borothermal reduction process.The proposed formation mechanism of HfB_(2) is completely different from the traditional two-step transformation method.After the sintering of the ultrafine powders,the HfB_(2) ceramics show a relative density of 96.1%and superior mechanical properties compared to other works.Furthermore,by simply replacing the initial metal source,chlorinated group IV and V transitional metals(Ti,Zr,Ta,Nb)can also convert into high-purity and ultrafine diborides.This work shows that flocculating settling assisted carbo/borothermal reduction has potential in lot size production of various high-purity and ultrafine boride powders.展开更多
基金financially supported by the Natural Science Foundation of China (Grant No.21473093)Fundamental Research Funds for the Central Universities and Tianjin Research Program of Application Foundation and Advanced Technology (Grant No.14JCYBJC41300)Ph.D. Candidate Research Innovation Fund of Nankai University
文摘MoS_2 has attracted attention as a promising hydrogen evolution reaction(HER) catalyst and a supercapacitor electrode material. However, its catalytic activity and capacitive performance are still hindered by its aggregation and poor intrinsic conductivity. Here, hollow rGO sphere-supported ultrathin MoS_2 nanosheet arrays(hrGO@MoS_2) are constructed via a dual-template approach and employed as bifunctional HER catalyst and supercapacitor electrode material. Because of the expanded interlayer spacing in MoS_2 nanosheets and more exposed electroactive S–Mo–S edges, the constructed h-rGO@MoS_2 architectures exhibit enhanced HER performance. Furthermore, benefiting from the synergistic effect of the improved conductivity and boosted specific surface areas(144.9 m^2 g^(-1), ca. 4.6-times that of pristine MoS_2), the h-rGO@MoS_2 architecture shows a high specific capacitance(238 F g^(-1) at a current density of 0.5 A g^(-1)), excellent rate capacitance, and remarkable cycle stability. Our synthesis method may be extended to construct other vertically aligned hollow architectures,which may serve both as efficient HER catalysts and supercapacitor electrodes.
基金the National Basic Research Program of China (No. 2013CB934304)Key Research Program of Frontier Sciences, CAS (No. QYZDJ-SSW-SLH046)+1 种基金CAS/SAFEA International Partnership Program for Creative Research Teams, the Natural Science Foundation of China (Nos. 21673245, 51632009, 51628202, 51472245 and 51671186)Hefei Institutes of Physical Sciences, CAS, and the Youth Innovation Promotion Association of CAS.
文摘A facile synthetic approach has been developed to prepare uniform and size-tunable spiky Au@Ag core-shell nan oparticles (NPs) to tailor the localized surface plasm on res onance (LSPR) properties. The gradual assembly of small Au nano crystals allows the size of spiky Au NPs to be modulated from tens to several hundreds of nano meters by tuning the concentration of initial Au seeds and Au source;and the thick ness of the Ag shell can be adjusted with stepwise reduction of Ag(l)ions. The LSPR bands of such spiky Au@Ag core-shell NPs resemble those of pure spiky Au NP cores of similar sizes in near-infrared region, and increasing the Ag shell thickness results in a blue shift and broadening of the LSPR band in the n ear-i nfrared regi on. Additi on ally, the spiky Au@Ag core-shell NPs exhibit improved surface-e nhan ced Rama n scattering (SERS) activity as compared to the bare spiky Au NPs and spherical Ag@Au NPs. This work has offered a facile route to synthesize plasmonic metal NPs with LSPR band in 650 to 800 nm that show strong enhancement of localized electromagnetic field, which provides an effective SERS substrate for SERS imaging and detection in biological fluids and tissues.
基金This work was financially supported by the National Basic Research Program of China （No. 2013CB934304）, the CAS/SAFEA International Partnership Program for Creative Research Teams, the National NaturalScience Foundation of China （Nos. 21303211, 11274312 and 51472245）.
文摘The surface topography of noble metal particles is a significant factor in tailoring surface-enhanced Raman scattering （SERS） properties. Here, we present a simple fabrication route to hexagonally arranged arrays of surface-roughened urchin- like Ag hemispheres （Ag-HSs） decorated with Ag nanoparticles （Ag-NPs） for highly active and reproducible SERS substrates. The urchin-like Ag-HS arrays are achieved by sputtering Ag onto the top surface of a highly ordered porous anodic aluminum oxide （AAO） template to form ordered arrays of smooth Ag-HSs and then by electrodepositing Ag-NPs onto the surface of each Ag-HS. Owing to the ordered arrangement of the Ag-HSs and the improved surface roughness, the urchin-like hierarchical Ag-HS arrays can provide sufficient and uniform ＂hot spots＂ for reproducible and highly active SERS effects. Using the urchin-like Ag-HS arrays as SERS substrates, 10-7 M dibutyl phthalate （a member of plasticizers family） and 1.5 × 10-5 M PCB-77 （one congener of polychlorinated biphenyl, a notorious class of pollutants） are identified, showing promising potential for these substrates in the rapid recognition of organic pollutants.
基金financially supported by the National Science Fund for Distinguished Young Scholars(No.51825103)the National Science Fund for Excellent Young Scholars(No.52222208)+1 种基金the Major science and technology project of Anhui Province(No.008192841048)the HFIPS Director's Fund,CAS(No.BJPY2021B04,YZJJ202202-CX,YZJJKX202202).
文摘In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phase precursor method can achieve uniform mixing of components at the molecular level through multiple complexation reactions,and then realize the carbo/borothermal reduction reaction at a lower temperature to obtain ultrapure HfB2 powders.The as-resulted quasi-spherical HfB2 powders under the optimum conditions(atomic molar ratio M:B:C=1:2.8:10)calcined at 1500°C for 1 h have an average particle size of 205 nm and an oxygen content of 0.097 wt.%.Detailed analysis of the phase evolution of precursors shows that the formation of HfB2 particles is a mass diffusion mode from the external to internal HfO_(2)cores.We reveal that below 1300°C,HfC is not an intermediate product of HfB2 powder during the transition of precursors.Instead,HfC was formed as a by-product at high temperatures in the carbo/borothermal reduction process.The proposed formation mechanism of HfB_(2) is completely different from the traditional two-step transformation method.After the sintering of the ultrafine powders,the HfB_(2) ceramics show a relative density of 96.1%and superior mechanical properties compared to other works.Furthermore,by simply replacing the initial metal source,chlorinated group IV and V transitional metals(Ti,Zr,Ta,Nb)can also convert into high-purity and ultrafine diborides.This work shows that flocculating settling assisted carbo/borothermal reduction has potential in lot size production of various high-purity and ultrafine boride powders.
