Combining the advantages of both heterogeneous and homogeneous catalysts,single-atom catalysts(SACs)with unique electronic properties have shown excellent catalytic properties.Herein,we report single-atom Pd dispersed...Combining the advantages of both heterogeneous and homogeneous catalysts,single-atom catalysts(SACs)with unique electronic properties have shown excellent catalytic properties.Herein,we report single-atom Pd dispersed on nanoscale TiO2 prepared by self-assembly method as efficient and selective catalysts for the hydrogenation of phenylacetylene to styrene.The catalysts were characterized by N2 adsorption/desorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and X-ray absorption spectroscopy(XAS).0.2 Pd-TiO2(150℃)possessing dominant single-atom Pd species,exhibited a turnover frequency(TOF)of over 8000 h^-1 with 91%selectivity towards styrene at room temperature.Further increasing Pd loading from 0.2%to 0.5%and 1.5%resulted in the decrease of activity probably due to the formation of Pd nanoparticles.Besides,the 0.2 Pd-TiO2 prepared by self-assembly strategy showed better catalytic performance than commercial 10%Pd/C and0.2 Pd-TiO2 synthesized by using impregnation method.展开更多
Titanium dioxide nanoparticle(nano-TiO2),as an excellent UV absorbent and photo-catalyst,has been widely applied in modem industry,thus inevitably discharged into environment.We proposed that nano-TiO2 in soil can pro...Titanium dioxide nanoparticle(nano-TiO2),as an excellent UV absorbent and photo-catalyst,has been widely applied in modem industry,thus inevitably discharged into environment.We proposed that nano-TiO2 in soil can promote crop yield through photosynthetic and metabolic disturbance,therefore,we investigated the effects of nano-TiO2 exposure on related physiologic-biochemical properties of rice(Oryza sativa L.).Results showed that rice biomass was increased>30%at every applied dosage(0.1-100 mg/L)of nano-TiO2.The actual photosynthetic rate(Y(II))significantly increased by 10.0%and 17.2%in the treatments of 10 and 100 mg/L respectively,indicating an increased energy production from photosynthesis.Besides,non-photochemical quenching(Y(NPQ))significantly decreased by 19.8%-26.0%of the control in all treatments respectively,representing a decline in heat dissipation.Detailed metabolism fingerprinting further revealed that a fortified transformation of monosaccharides(D-fructose,D-galactose,and D-talose)to disaccharides(D-cellobiose,and Dlactose)was accompanied with a weakened citric acid cycle,confirming the decrease of energy consumption in metabolism.All these results elucidated that nano-TiO2 promoted rice growth through the upregulation of energy storage in photosynthesis and the downregulation of energy consumption in metabolism.This study provides a mechanistic understanding of the stress-response hormesis of rice after exposure to nano-TiO2,and provides worthy information on the potential application and risk of nanomaterials in agricultural production.展开更多
基金supported by the National University of Singapore Flagship Green Energy Program (#R-279-000-553-646 and R-279-000-553-731)the National Natural Science Foundation of China (21908085)the Natural Science Foundation of Jiangsu Province,China (BK20190961)
文摘Combining the advantages of both heterogeneous and homogeneous catalysts,single-atom catalysts(SACs)with unique electronic properties have shown excellent catalytic properties.Herein,we report single-atom Pd dispersed on nanoscale TiO2 prepared by self-assembly method as efficient and selective catalysts for the hydrogenation of phenylacetylene to styrene.The catalysts were characterized by N2 adsorption/desorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and X-ray absorption spectroscopy(XAS).0.2 Pd-TiO2(150℃)possessing dominant single-atom Pd species,exhibited a turnover frequency(TOF)of over 8000 h^-1 with 91%selectivity towards styrene at room temperature.Further increasing Pd loading from 0.2%to 0.5%and 1.5%resulted in the decrease of activity probably due to the formation of Pd nanoparticles.Besides,the 0.2 Pd-TiO2 prepared by self-assembly strategy showed better catalytic performance than commercial 10%Pd/C and0.2 Pd-TiO2 synthesized by using impregnation method.
基金This work was supported by the National Natural Science Foundation of China(Nos.21836003 and 21520102009).
文摘Titanium dioxide nanoparticle(nano-TiO2),as an excellent UV absorbent and photo-catalyst,has been widely applied in modem industry,thus inevitably discharged into environment.We proposed that nano-TiO2 in soil can promote crop yield through photosynthetic and metabolic disturbance,therefore,we investigated the effects of nano-TiO2 exposure on related physiologic-biochemical properties of rice(Oryza sativa L.).Results showed that rice biomass was increased>30%at every applied dosage(0.1-100 mg/L)of nano-TiO2.The actual photosynthetic rate(Y(II))significantly increased by 10.0%and 17.2%in the treatments of 10 and 100 mg/L respectively,indicating an increased energy production from photosynthesis.Besides,non-photochemical quenching(Y(NPQ))significantly decreased by 19.8%-26.0%of the control in all treatments respectively,representing a decline in heat dissipation.Detailed metabolism fingerprinting further revealed that a fortified transformation of monosaccharides(D-fructose,D-galactose,and D-talose)to disaccharides(D-cellobiose,and Dlactose)was accompanied with a weakened citric acid cycle,confirming the decrease of energy consumption in metabolism.All these results elucidated that nano-TiO2 promoted rice growth through the upregulation of energy storage in photosynthesis and the downregulation of energy consumption in metabolism.This study provides a mechanistic understanding of the stress-response hormesis of rice after exposure to nano-TiO2,and provides worthy information on the potential application and risk of nanomaterials in agricultural production.
