Hydrogen with high energy density is an environmental alternative to fossil fuels which can respond to the demand for energy considering environmental conditions.It can be stored on porous materials employing physical...Hydrogen with high energy density is an environmental alternative to fossil fuels which can respond to the demand for energy considering environmental conditions.It can be stored on porous materials employing physical interaction(e.g.adsorption process).The H2storage capacity of materials can be evaluated through electrochemical methods.Therefore,a fast and straightforward approach was employed to fabricate magnesium oxide/chitosan/Au nanoparticles(Mg O/CS/Au)nanocomposites with porous structure for electrochemical hydrogen storage.Herein,laser ablation in water as a fast and green method was utilized to obtain Au nanoparticles(Au NPs).The obtained Au NPs were loaded on Mg O/CS nanocomposite through physical mixing.Structural and morphological investigation of nanocomposites display spherically shaped Au NPs with a diameter of 49–58 nm agglomerated on the Mg O/CS.Drop casting,the fast and cost-effective method was deployed to deposit the benign,and reusable Mg O/CS/Au-x(x is Au NPs weight percentage of 1,3 and 5 wt.%)nanocomposites on stainless steel mesh and their electrochemical hydrogen storage were measured by cyclic voltammetry(CV),indicating good stability and significant hydrogen storage capacity(28 C/g)after 300 CV scans for MgO/CS/Au-1 sample.展开更多
Proton-exchange membrane water electrolysis(PEM WE)is a particularly promising technology for renewable hydrogen produc-tion.However,the excessive passivation of the gas diffusion layer(GDL)will seriously affect the h...Proton-exchange membrane water electrolysis(PEM WE)is a particularly promising technology for renewable hydrogen produc-tion.However,the excessive passivation of the gas diffusion layer(GDL)will seriously affect the high surface-contact resistance and result in energy losses.Thus,a mechanism for improving the conductivity and interface stability of the GDL is an urgent issue.In this work,we have prepared a hydrophilic and corrosion resistant conductive composite protective coating.The polydopamine(PDA)film on the Ti surface,which was obtained via the solution oxidation method,ensured that neither micropores nor pinholes existed in the final hybrid coatings.In-situ reduced gold nanoparticles(AuNPs)improved the conductivity to achieve the desired interfacial contact resistance and further enhanced the corrosion resistance.The surface composition of the treated samples was investigated using scanning electron microscopy(SEM),transmis-sion electron microscopy(TEM),X-ray diffraction(XRD),and Fourier transform infrared spectroscopy(FTIR).The results indicated that the optimized reaction conditions included a pH value of 3 of HAuCl_(4) solution with PDA deposition(48 h)on papers and revealed the lowest con-tact resistance(0.5 mΩ·cm^(2))and corrosion resistance(0.001μA·cm^(−2))in a 0.5 M H_(2)SO_(4)+2 ppm F−solution(1.7 V vs.RHE)among all the modified specimens,where RHE represents reversible hydrogen electrode.These findings indicated that the Au-PDA coating is very appropriate for the modification of Ti GDLs in PEM WE systems.展开更多
Bimetallic gold-silver core-shell nanoparticles were prepared by chemical reduction in aqueous solution, following a method that was friendly to the environment, allowing us to use this for medicinal purposes. Gold na...Bimetallic gold-silver core-shell nanoparticles were prepared by chemical reduction in aqueous solution, following a method that was friendly to the environment, allowing us to use this for medicinal purposes. Gold nanoparticles were synthesized, and silver cations were then reduced on the nanoparticles. Using the optical properties of metallic nanoparticles, surface plasmon resonance was determined by UV-Vis spectroscopy, and the values obtained for gold and silver were approximately 520 nm and 400 nm in wavelength, respectively. The absorption peaks of the surface plasmon band show a clear red-shift due to size effect in the case of the silver surface, and a plasmon coupling effect, in the case of gold. To obtain a better understanding of the coating conditions, high resolution transmission electron microscopy was used. The average hydrodynamic size and the size distribution of the synthesized nanoparticles were obtained by dynamic light scattering. The development of this process, which is benign for the environment, opens the possibility for many applications in the areas of renewable energy, medicine and biology.展开更多
Two sets of gold nanoparticles (NP) embedded in amorphous BaTiO3 films were prepared by sol-gel method using spin coating. Sample (1) is having BaTiO3 sol with 0.025 gm of Chloroauric acid dissolved in 10 ml of propan...Two sets of gold nanoparticles (NP) embedded in amorphous BaTiO3 films were prepared by sol-gel method using spin coating. Sample (1) is having BaTiO3 sol with 0.025 gm of Chloroauric acid dissolved in 10 ml of propan-2-ol, while sample (2) is having 0.086 gm of Chloroauric acid in the same amount of propan-2-ol. The films have been deposited on various substrates like borosilicate glass and fused silica. TEM images show that the particles are of 5 and 10 nm in size for the two set of samples, and some are having elongated morphology. Optical absorption properties of these films reveal the substrate and size effect on localised surface plasmon resonance (SPR). It shows a marginal red shift in the plasmon resonance peak from 414 nm to 420 nm in the case of sample (1) and 566 nm to 568 nm for sample (2) as the substrate changed from borosilicate glass to fused silica. It also shows red shift in Plasmon peak as the size increases from 5 to 10 nm and coincides with Mie explanation for the shift with size.展开更多
We prepared Au/Ag core-shell nanoparticles by growing Ag shell onto 12 nm Au core, using silver nitrate and sodium citrate as the reactants. By changing the molar ratio of Ag to Au, the shell thickness and thus the si...We prepared Au/Ag core-shell nanoparticles by growing Ag shell onto 12 nm Au core, using silver nitrate and sodium citrate as the reactants. By changing the molar ratio of Ag to Au, the shell thickness and thus the size of bimetallic particles could be controlled in convenient way. The formation of core-shell structure was proved by UV-Vis spectra, transmission electron microscopy(TEM), etc.. The core-shell particles showed a more narrow size distribution than Ag colloid prepared without Au core. The SERS activity of the core-shell particles was investigated by using 2,4-dimethylpyridine as the probe, which strongly indicated their potential application in SERS substrate materials.展开更多
文摘Hydrogen with high energy density is an environmental alternative to fossil fuels which can respond to the demand for energy considering environmental conditions.It can be stored on porous materials employing physical interaction(e.g.adsorption process).The H2storage capacity of materials can be evaluated through electrochemical methods.Therefore,a fast and straightforward approach was employed to fabricate magnesium oxide/chitosan/Au nanoparticles(Mg O/CS/Au)nanocomposites with porous structure for electrochemical hydrogen storage.Herein,laser ablation in water as a fast and green method was utilized to obtain Au nanoparticles(Au NPs).The obtained Au NPs were loaded on Mg O/CS nanocomposite through physical mixing.Structural and morphological investigation of nanocomposites display spherically shaped Au NPs with a diameter of 49–58 nm agglomerated on the Mg O/CS.Drop casting,the fast and cost-effective method was deployed to deposit the benign,and reusable Mg O/CS/Au-x(x is Au NPs weight percentage of 1,3 and 5 wt.%)nanocomposites on stainless steel mesh and their electrochemical hydrogen storage were measured by cyclic voltammetry(CV),indicating good stability and significant hydrogen storage capacity(28 C/g)after 300 CV scans for MgO/CS/Au-1 sample.
基金supported by the National Key Research and Development Program of China(No.2018 YFB1502403)。
文摘Proton-exchange membrane water electrolysis(PEM WE)is a particularly promising technology for renewable hydrogen produc-tion.However,the excessive passivation of the gas diffusion layer(GDL)will seriously affect the high surface-contact resistance and result in energy losses.Thus,a mechanism for improving the conductivity and interface stability of the GDL is an urgent issue.In this work,we have prepared a hydrophilic and corrosion resistant conductive composite protective coating.The polydopamine(PDA)film on the Ti surface,which was obtained via the solution oxidation method,ensured that neither micropores nor pinholes existed in the final hybrid coatings.In-situ reduced gold nanoparticles(AuNPs)improved the conductivity to achieve the desired interfacial contact resistance and further enhanced the corrosion resistance.The surface composition of the treated samples was investigated using scanning electron microscopy(SEM),transmis-sion electron microscopy(TEM),X-ray diffraction(XRD),and Fourier transform infrared spectroscopy(FTIR).The results indicated that the optimized reaction conditions included a pH value of 3 of HAuCl_(4) solution with PDA deposition(48 h)on papers and revealed the lowest con-tact resistance(0.5 mΩ·cm^(2))and corrosion resistance(0.001μA·cm^(−2))in a 0.5 M H_(2)SO_(4)+2 ppm F−solution(1.7 V vs.RHE)among all the modified specimens,where RHE represents reversible hydrogen electrode.These findings indicated that the Au-PDA coating is very appropriate for the modification of Ti GDLs in PEM WE systems.
文摘Bimetallic gold-silver core-shell nanoparticles were prepared by chemical reduction in aqueous solution, following a method that was friendly to the environment, allowing us to use this for medicinal purposes. Gold nanoparticles were synthesized, and silver cations were then reduced on the nanoparticles. Using the optical properties of metallic nanoparticles, surface plasmon resonance was determined by UV-Vis spectroscopy, and the values obtained for gold and silver were approximately 520 nm and 400 nm in wavelength, respectively. The absorption peaks of the surface plasmon band show a clear red-shift due to size effect in the case of the silver surface, and a plasmon coupling effect, in the case of gold. To obtain a better understanding of the coating conditions, high resolution transmission electron microscopy was used. The average hydrodynamic size and the size distribution of the synthesized nanoparticles were obtained by dynamic light scattering. The development of this process, which is benign for the environment, opens the possibility for many applications in the areas of renewable energy, medicine and biology.
文摘Two sets of gold nanoparticles (NP) embedded in amorphous BaTiO3 films were prepared by sol-gel method using spin coating. Sample (1) is having BaTiO3 sol with 0.025 gm of Chloroauric acid dissolved in 10 ml of propan-2-ol, while sample (2) is having 0.086 gm of Chloroauric acid in the same amount of propan-2-ol. The films have been deposited on various substrates like borosilicate glass and fused silica. TEM images show that the particles are of 5 and 10 nm in size for the two set of samples, and some are having elongated morphology. Optical absorption properties of these films reveal the substrate and size effect on localised surface plasmon resonance (SPR). It shows a marginal red shift in the plasmon resonance peak from 414 nm to 420 nm in the case of sample (1) and 566 nm to 568 nm for sample (2) as the substrate changed from borosilicate glass to fused silica. It also shows red shift in Plasmon peak as the size increases from 5 to 10 nm and coincides with Mie explanation for the shift with size.
文摘We prepared Au/Ag core-shell nanoparticles by growing Ag shell onto 12 nm Au core, using silver nitrate and sodium citrate as the reactants. By changing the molar ratio of Ag to Au, the shell thickness and thus the size of bimetallic particles could be controlled in convenient way. The formation of core-shell structure was proved by UV-Vis spectra, transmission electron microscopy(TEM), etc.. The core-shell particles showed a more narrow size distribution than Ag colloid prepared without Au core. The SERS activity of the core-shell particles was investigated by using 2,4-dimethylpyridine as the probe, which strongly indicated their potential application in SERS substrate materials.
