We prepared the Fe3O4/g‐C3N4nanoparticles(NPs)through a simple electrostatic self‐assembly method with a3:97weight ratio to investigate their Fenton,photo‐Fenton and oxidative functionalities besides photocatalytic...We prepared the Fe3O4/g‐C3N4nanoparticles(NPs)through a simple electrostatic self‐assembly method with a3:97weight ratio to investigate their Fenton,photo‐Fenton and oxidative functionalities besides photocatalytic functionality.We observed an improvement of the Fenton and photo‐Fenton activities of the Fe3O4/g‐C3N4nanocomposites.This improvement was attributed to efficient charge transfer between Fe3O4and g‐C3N4at the heterojunctions,inhibition of electron‐hole recombination,a high surface area,and stabilization of Fe3O4against leaching by the hydrophobic g‐C3N4.The obtained NPs showed a higher degradation potential for rhodamine B(RhB)dye than those of Fe3O4and g‐C3N4.As compared to photocatalysis,the efficiency of RhB degradation in the Fenton and photo‐Fenton reactions was increased by20%and90%,respectively.Additionally,the horseradish peroxidase(HRP)activity of the prepared nanomaterials was studied with3,3,5,5‐tetramethylbenzidinedihydrochloride(TMB)as a substrate.Dopamine oxidation was also examined.Results indicate that Fe3O4/g‐C3N4nanocomposites offers more efficient degradation of RhB dye in a photo‐Fenton system compared with regular photocatalytic degradation,which requires a long time.Our study also confirmed that Fe3O4/g‐C3N4nanocomposites can be used as a potential material for mimicking HRP owing to its high affinity for TMB.These findings suggest good potential for applications in biosensing and as a catalyst in oxidation reactions.展开更多
Si3N4/TiC nanocomposite ceramics have been fabricated by hot pressing technique with Al2O3 and Y2O3 as additives. The results showed that well dispersed composite powder was carried out by adding dispersant and adjust...Si3N4/TiC nanocomposite ceramics have been fabricated by hot pressing technique with Al2O3 and Y2O3 as additives. The results showed that well dispersed composite powder was carried out by adding dispersant and adjusting pH values of suspensions. Remarkable increase in flexural strength at room temperatures was obtained by adding nanoparticles in Si3N4 matrix with 10% （wt pct） of nano-Si3N4 and 15% of nano-TiC. The flexural strength, fracture toughness and hardness were 1025 MPa, 7.5 MPa.m^1/2 and 15.6 GPa, respectively. The microstructures of materials were analyzed by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, which indicated that TiC nanoparticles distribute in the matrix and at the grain boundaries. According to the fracture form, low contents of nano particles could refine matrix grains and lead to the crack deflection as well as crack pinning. The multiplex microstructure was formed by mixing nano-Si3N4 particles. The crack trajectories exhibited crack deflection, rod-like grain bridging and pull-out.展开更多
Novel barium tungstate/nitrogen-doped reduced graphene oxide-graphi- tic carbon nitride （BaWO4/NRGO-g-C3N4） nanocomposite has been synthesized by a simple one-pot microwave technique. The synthesized nanocomposites ...Novel barium tungstate/nitrogen-doped reduced graphene oxide-graphi- tic carbon nitride （BaWO4/NRGO-g-C3N4） nanocomposite has been synthesized by a simple one-pot microwave technique. The synthesized nanocomposites are well characterized by diffraction, microscopic and spectroscopic techniques to study its crystal structure, elemental composition, morphological features and optical properties. The material prepared is tested for its performance as an electrocatalyst, photocatalyst and reduction catalyst. The nanocomposite catalyzed the photodegradation of methylene blue （MB） dye in 120 min, reduction of 4-nitro phenol （4-NP） to 4-amino phenol （4-AP） in 60 s, showed an impressive Tafel slope of 62 mV/dec for hydrogen evolution reaction （HER）. The observed results suggest that the nanocomposite acts as an efficient multifunctional catalyst. The reported approach provides fundamental insights which can be extended to other metal tungstate-based ternary composites for applications in the field of clean energy and environment in the future.展开更多
Si2N2O/Si3N4 nanocomposites were fabricated by liquid phase sintering of amorphous nano-sized silicon nitride powders.The intragranular microstructure was observed and researched.Intragranular microstructure's β-...Si2N2O/Si3N4 nanocomposites were fabricated by liquid phase sintering of amorphous nano-sized silicon nitride powders.The intragranular microstructure was observed and researched.Intragranular microstructure's β-Si3N4 was formed in Si2N2O matrix at the sintering temperature higher than 1650°C.It was discovered that intragranular microstructure could also disappear by transformation during high temperature annealing.Two possible mechanisms of the disappearance of intragranular microstructure were given.The effect of intragranular microstructure on main mechanical properties was also investigated.展开更多
The CeVO_4/graphitic C_3N_4 composites have exhibited much enhanced photocatalytic property for degrading methylene blue(MB) pollutant under visible light irradiation compared with single-phase g-C_3N_4 or CeVO_4. The...The CeVO_4/graphitic C_3N_4 composites have exhibited much enhanced photocatalytic property for degrading methylene blue(MB) pollutant under visible light irradiation compared with single-phase g-C_3N_4 or CeVO_4. The composite S5 obtained from an optimized mass ratio(5%) of CeVO_4 to dicyanamide(DCDA) exhibits the highest photocatalytic activity. Here, ternary Ag/CeVO_4/g-C_3N_4 composites denoted as X%Ag/S5 were prepared by an ultrasonic precipitation method to improve the photocatalytic property of S5. The TEM images show that CeVO_4 and Ag nanoparticles are well distributed on the layered g-C_3N_4, which agree well with the XRD results. The UV spectra show that the 7%Ag/S5 sample has the widest absorption range and the enhanced absorption intensity under visible light irradiation. The corresponding band gap of 7%Ag/S5(2.5 eV) is much lower than that of S5(2.65 eV). The corresponding k value of 7%Ag/S5 is much higher than those of g-C_3N_4 and CeVO_4. The degradation experiments for MB solution suggest that the 7%Ag/S5 sample has the optimal photocatalytic performance, which can degrade MB solution completely within 120 min. The enhanced photocatalytic property of the composites is ascribed to not only the effect of heterojunction structure, but also the surface plasma resonance effect of Ag nanoparticles.展开更多
基金supported by the National Natural Science Foundation of China(51572253,21771171)Scientific Research Grant of Hefei Science Center of CAS(2015SRG-HSC048)+1 种基金cooperation between NSFC and Netherlands Organization for Scientific Research(51561135011)CAS-TWAS Scholarship Program~~
文摘We prepared the Fe3O4/g‐C3N4nanoparticles(NPs)through a simple electrostatic self‐assembly method with a3:97weight ratio to investigate their Fenton,photo‐Fenton and oxidative functionalities besides photocatalytic functionality.We observed an improvement of the Fenton and photo‐Fenton activities of the Fe3O4/g‐C3N4nanocomposites.This improvement was attributed to efficient charge transfer between Fe3O4and g‐C3N4at the heterojunctions,inhibition of electron‐hole recombination,a high surface area,and stabilization of Fe3O4against leaching by the hydrophobic g‐C3N4.The obtained NPs showed a higher degradation potential for rhodamine B(RhB)dye than those of Fe3O4and g‐C3N4.As compared to photocatalysis,the efficiency of RhB degradation in the Fenton and photo‐Fenton reactions was increased by20%and90%,respectively.Additionally,the horseradish peroxidase(HRP)activity of the prepared nanomaterials was studied with3,3,5,5‐tetramethylbenzidinedihydrochloride(TMB)as a substrate.Dopamine oxidation was also examined.Results indicate that Fe3O4/g‐C3N4nanocomposites offers more efficient degradation of RhB dye in a photo‐Fenton system compared with regular photocatalytic degradation,which requires a long time.Our study also confirmed that Fe3O4/g‐C3N4nanocomposites can be used as a potential material for mimicking HRP owing to its high affinity for TMB.These findings suggest good potential for applications in biosensing and as a catalyst in oxidation reactions.
基金supported by the National Natural Sci ence Foundation of China(No.50105011)the Foundation for the author by the National Excellent Doctoral Disserta tion of China(200231)+2 种基金the Natural Science Foundation of Shandong Province(Y2004F14)the SRF for ROCS([2002]247),MOE,Chinathe SRF for ROCS(2002[247]),SEM.
文摘Si3N4/TiC nanocomposite ceramics have been fabricated by hot pressing technique with Al2O3 and Y2O3 as additives. The results showed that well dispersed composite powder was carried out by adding dispersant and adjusting pH values of suspensions. Remarkable increase in flexural strength at room temperatures was obtained by adding nanoparticles in Si3N4 matrix with 10% （wt pct） of nano-Si3N4 and 15% of nano-TiC. The flexural strength, fracture toughness and hardness were 1025 MPa, 7.5 MPa.m^1/2 and 15.6 GPa, respectively. The microstructures of materials were analyzed by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, which indicated that TiC nanoparticles distribute in the matrix and at the grain boundaries. According to the fracture form, low contents of nano particles could refine matrix grains and lead to the crack deflection as well as crack pinning. The multiplex microstructure was formed by mixing nano-Si3N4 particles. The crack trajectories exhibited crack deflection, rod-like grain bridging and pull-out.
文摘Novel barium tungstate/nitrogen-doped reduced graphene oxide-graphi- tic carbon nitride （BaWO4/NRGO-g-C3N4） nanocomposite has been synthesized by a simple one-pot microwave technique. The synthesized nanocomposites are well characterized by diffraction, microscopic and spectroscopic techniques to study its crystal structure, elemental composition, morphological features and optical properties. The material prepared is tested for its performance as an electrocatalyst, photocatalyst and reduction catalyst. The nanocomposite catalyzed the photodegradation of methylene blue （MB） dye in 120 min, reduction of 4-nitro phenol （4-NP） to 4-amino phenol （4-AP） in 60 s, showed an impressive Tafel slope of 62 mV/dec for hydrogen evolution reaction （HER）. The observed results suggest that the nanocomposite acts as an efficient multifunctional catalyst. The reported approach provides fundamental insights which can be extended to other metal tungstate-based ternary composites for applications in the field of clean energy and environment in the future.
基金supported by National Postdoctoral Foundation of China (Grant No.20060400787)Science Foundation of China (Grant No.50901066)
文摘Si2N2O/Si3N4 nanocomposites were fabricated by liquid phase sintering of amorphous nano-sized silicon nitride powders.The intragranular microstructure was observed and researched.Intragranular microstructure's β-Si3N4 was formed in Si2N2O matrix at the sintering temperature higher than 1650°C.It was discovered that intragranular microstructure could also disappear by transformation during high temperature annealing.Two possible mechanisms of the disappearance of intragranular microstructure were given.The effect of intragranular microstructure on main mechanical properties was also investigated.
基金supported by National Natural Science Foundation of China(No.51502116)the Six Talents Peak Project in Jiangsu Province(No.2011-ZBZZ045)+2 种基金Natural Science Foundation of Jiangsu Province(No.BK20140557)Special Funding of China Postdoctoral Science Foundation(No.2016T90425)China Postdoctoral Science Foundation(No.2015M571682)
文摘The CeVO_4/graphitic C_3N_4 composites have exhibited much enhanced photocatalytic property for degrading methylene blue(MB) pollutant under visible light irradiation compared with single-phase g-C_3N_4 or CeVO_4. The composite S5 obtained from an optimized mass ratio(5%) of CeVO_4 to dicyanamide(DCDA) exhibits the highest photocatalytic activity. Here, ternary Ag/CeVO_4/g-C_3N_4 composites denoted as X%Ag/S5 were prepared by an ultrasonic precipitation method to improve the photocatalytic property of S5. The TEM images show that CeVO_4 and Ag nanoparticles are well distributed on the layered g-C_3N_4, which agree well with the XRD results. The UV spectra show that the 7%Ag/S5 sample has the widest absorption range and the enhanced absorption intensity under visible light irradiation. The corresponding band gap of 7%Ag/S5(2.5 eV) is much lower than that of S5(2.65 eV). The corresponding k value of 7%Ag/S5 is much higher than those of g-C_3N_4 and CeVO_4. The degradation experiments for MB solution suggest that the 7%Ag/S5 sample has the optimal photocatalytic performance, which can degrade MB solution completely within 120 min. The enhanced photocatalytic property of the composites is ascribed to not only the effect of heterojunction structure, but also the surface plasma resonance effect of Ag nanoparticles.
