A high-performance ammonia(NH3)sensor is prepared based on CeO_(2)/NiO composite,using a hydrothermal method.Experimental findings confirm that the CeO_(2)/NiO composite significantly enhances the performance of the N...A high-performance ammonia(NH3)sensor is prepared based on CeO_(2)/NiO composite,using a hydrothermal method.Experimental findings confirm that the CeO_(2)/NiO composite significantly enhances the performance of the NiO-based NH3 sensor.This improvement is primarily due to the increase in oxygen vacancies(Ov),chemically adsorbed oxygen(Oc),and the proportion of Ni3+on the surface of the CeO_(2)/NiO.The CeO_(2)/NiO sensor shows a high response to NH3,exhibiting response/recovery times of 1.8 s/0.9 s at the NH3 concentration of 5×10^(−6)mL/m^(3),with the theoretical lowest detection limit of 98.651×10^(−9)mL/m^(3).Additionally,the CeO_(2)/NiO sensor has been successfully applied in the simulated detection of Helicobacter pylori infection,highlighting its significant research value and potential application prospects in biomedical diagnostics.展开更多
采用简单的静电纺丝方法制备了Ni/NiO/C负极材料。XRD证明该材料主要由NiO、Ni和无定形碳组成。SEM证明Ni/NiO/C的形貌呈纤维状,纤维的直径为400~500 nm。以Ni/NiO/C为锂电的负极材料,在100 mA g^(-1)的电流密度下,首次充电比容量可达到...采用简单的静电纺丝方法制备了Ni/NiO/C负极材料。XRD证明该材料主要由NiO、Ni和无定形碳组成。SEM证明Ni/NiO/C的形貌呈纤维状,纤维的直径为400~500 nm。以Ni/NiO/C为锂电的负极材料,在100 mA g^(-1)的电流密度下,首次充电比容量可达到586.5 mAh g^(-1),循环50圈后的充电比容量仍可达到453.2 mAh g^(-1),容量保持率为77.27%。展开更多
In our previous study,the activity and stability of the Mo/HZSM-5 catalyst were enhanced by mixing physically with NiO in methane dehydroaromatization(MDA)reaction.It has been confirmed that the physically mixed NiO n...In our previous study,the activity and stability of the Mo/HZSM-5 catalyst were enhanced by mixing physically with NiO in methane dehydroaromatization(MDA)reaction.It has been confirmed that the physically mixed NiO not only promoted the dispersion of MoC_(x)active sites but also reduced the coke formation on the MoC_(x)owing to the CNTs growth on Ni.However,the promotional effect of NiO was limited when the particle size was reduced,due to the excessive interaction with MoOx(forming NiMoO_(4))which is detrimental to the MoC_(x)dispersion.In this study,to overcome the limitation,silica shell on NiO particles with various sizes(5,15,110 nm)was introduced.The catalyst with silica shell coated NiO with the size of 15 nm exhibited a significant improvement in both BTX yield and stability,and the catalyst with silica shell coated NiO with the size of 5 nm achieved the highest maximum BTX yield,about 7.2%.This study demonstrates that the catalytic performance improved as the NiO particle size decreased with the introduction of the silica shell.Combined transmission electron microscopy-energy dispersive spectroscopy,X-ray diffraction,temperature-programmed surface reaction of methane,CO chemisorption,visible Raman,and thermogravimetric analysis allowed us to confirm that a thin silica shell further enhances the MoC_(x)dispersion while preventing the formation of Ni-Mo complexes.However,when the size of NiO decreased to 5 nm,CNT growth on Ni was limited during the reaction,which is crucial for reducing coke formation on Mo active sites,thereby resulting in the decreased catalyst stabilization ability of Ni.Overall,this study indicates that the introduction of a silica shell in a controlled way can significantly enhance the promotional effect of physically mixed NiO on MDA.展开更多
Nickel oxide(NiO)based gas sensors have at-tracted intense attention due to its high re-sponse to hydrogen sulfide(H_(2)S)gas.It has been demonstrated that the NiO sensors with exposed(111)facet exhibit excellent perf...Nickel oxide(NiO)based gas sensors have at-tracted intense attention due to its high re-sponse to hydrogen sulfide(H_(2)S)gas.It has been demonstrated that the NiO sensors with exposed(111)facet exhibit excellent perfor-mance,but the single-orientation NiO sensors with exposed(111)facet have rarely been studied.In this work,high quality(111)-ori-ented NiO epitaxial films were fabricated by pulsed laser deposition.Detailed crystalline structural information was revealed by using synchrotron based X-ray diffraction(XRD)technology.These NiO thin films show good se-lectivity for H_(2)S gas detection.Without further modification,the highest response to 100 ppm H_(2)S was measured to be 13.07 at 300℃,and limit of detection(LOD)could be as low as 186 ppb.Fitting of the electrical response curves during adsorption and desorption of H_(2)S gas indicates the two-site Langmuir kinetic processes.Combining with XPS and XAS measure-ments,the mechanism was discussed.Density functional theory(DFT)calculations show that NiO with exposed(111)facets has the most negative adsorption energy,indicating more sen-sitive to H_(2)S.These results could inspire more studies of metal oxide semiconductor-based gas sensors with specific surface.展开更多
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China“Preparation and application of self-powered carbon nitride/metal oxide humidity sensors”(2023D01C05).
文摘A high-performance ammonia(NH3)sensor is prepared based on CeO_(2)/NiO composite,using a hydrothermal method.Experimental findings confirm that the CeO_(2)/NiO composite significantly enhances the performance of the NiO-based NH3 sensor.This improvement is primarily due to the increase in oxygen vacancies(Ov),chemically adsorbed oxygen(Oc),and the proportion of Ni3+on the surface of the CeO_(2)/NiO.The CeO_(2)/NiO sensor shows a high response to NH3,exhibiting response/recovery times of 1.8 s/0.9 s at the NH3 concentration of 5×10^(−6)mL/m^(3),with the theoretical lowest detection limit of 98.651×10^(−9)mL/m^(3).Additionally,the CeO_(2)/NiO sensor has been successfully applied in the simulated detection of Helicobacter pylori infection,highlighting its significant research value and potential application prospects in biomedical diagnostics.
文摘采用简单的静电纺丝方法制备了Ni/NiO/C负极材料。XRD证明该材料主要由NiO、Ni和无定形碳组成。SEM证明Ni/NiO/C的形貌呈纤维状,纤维的直径为400~500 nm。以Ni/NiO/C为锂电的负极材料,在100 mA g^(-1)的电流密度下,首次充电比容量可达到586.5 mAh g^(-1),循环50圈后的充电比容量仍可达到453.2 mAh g^(-1),容量保持率为77.27%。
文摘In our previous study,the activity and stability of the Mo/HZSM-5 catalyst were enhanced by mixing physically with NiO in methane dehydroaromatization(MDA)reaction.It has been confirmed that the physically mixed NiO not only promoted the dispersion of MoC_(x)active sites but also reduced the coke formation on the MoC_(x)owing to the CNTs growth on Ni.However,the promotional effect of NiO was limited when the particle size was reduced,due to the excessive interaction with MoOx(forming NiMoO_(4))which is detrimental to the MoC_(x)dispersion.In this study,to overcome the limitation,silica shell on NiO particles with various sizes(5,15,110 nm)was introduced.The catalyst with silica shell coated NiO with the size of 15 nm exhibited a significant improvement in both BTX yield and stability,and the catalyst with silica shell coated NiO with the size of 5 nm achieved the highest maximum BTX yield,about 7.2%.This study demonstrates that the catalytic performance improved as the NiO particle size decreased with the introduction of the silica shell.Combined transmission electron microscopy-energy dispersive spectroscopy,X-ray diffraction,temperature-programmed surface reaction of methane,CO chemisorption,visible Raman,and thermogravimetric analysis allowed us to confirm that a thin silica shell further enhances the MoC_(x)dispersion while preventing the formation of Ni-Mo complexes.However,when the size of NiO decreased to 5 nm,CNT growth on Ni was limited during the reaction,which is crucial for reducing coke formation on Mo active sites,thereby resulting in the decreased catalyst stabilization ability of Ni.Overall,this study indicates that the introduction of a silica shell in a controlled way can significantly enhance the promotional effect of physically mixed NiO on MDA.
基金supported by the National Key Research and Development Program of China(No.2022YFA1603902)the National Natural Science Foundation of China(No.12175235,No.62271462,and No.12004407)。
文摘Nickel oxide(NiO)based gas sensors have at-tracted intense attention due to its high re-sponse to hydrogen sulfide(H_(2)S)gas.It has been demonstrated that the NiO sensors with exposed(111)facet exhibit excellent perfor-mance,but the single-orientation NiO sensors with exposed(111)facet have rarely been studied.In this work,high quality(111)-ori-ented NiO epitaxial films were fabricated by pulsed laser deposition.Detailed crystalline structural information was revealed by using synchrotron based X-ray diffraction(XRD)technology.These NiO thin films show good se-lectivity for H_(2)S gas detection.Without further modification,the highest response to 100 ppm H_(2)S was measured to be 13.07 at 300℃,and limit of detection(LOD)could be as low as 186 ppb.Fitting of the electrical response curves during adsorption and desorption of H_(2)S gas indicates the two-site Langmuir kinetic processes.Combining with XPS and XAS measure-ments,the mechanism was discussed.Density functional theory(DFT)calculations show that NiO with exposed(111)facets has the most negative adsorption energy,indicating more sen-sitive to H_(2)S.These results could inspire more studies of metal oxide semiconductor-based gas sensors with specific surface.
