271
porous structure of nickel, a large number of Au nanoparticles could be anchored on
the surface through multivalent host-guest interactions, and the reactant solution
could be catalyzed by flowing through the pores. Because of the photoisomerization
property of azobenzene, the multivalent host-guest interactions between
β-cyclodextrin and azobenzene could be removed by UV irradiation. Thus, the gold
nanoparticles could be anchored on or removed from the surface of the porous
nickel. Different electrocatalysts were prepared by increasing the gold amount.
These electrocatalysts had been evaluated in the oxygen electroreduction and compared to the unmodified electrode. The authors observed an activity enhancement
for the poly(aminothiophenol)-Au nano which can be explained by small crystallite
sizes and good distribution of gold nanoparticles on the surface of the polymer.
Platinum nanoworms self-assemble with a β-cyclodextrin polymer/reduced graphene oxide via the use of 4-aminothiophenol as nanoparticle capping agent incorporated in the cyclodextrin cavities (Gopalan et al. 2006). The cyclodextrin-based
polymer was synthesized by cross-linking β-cyclodextrin with epichlorohydrin and
the graphene oxide from natural graphite. The polymer of cyclodextrin was modified on graphene oxide, and the resulting composite was dispersed in ethanol and
mixed with polyaminothiophenol. The modified graphene oxide was reduced by
hydrazine and filtered before the addition of Pt nanoworms. The interactions of the
4-aminothiophenol and the polymer of cyclodextrin were evaluated by UV-Vis
spectroscopy and by FTIR spectroscopy. One interaction gave a red shift corresponding to the thiol/amino group from 251 nm to 256 nm. Moreover, all the characteristic peaks of 4-aminothiophenol were not observed because 4-aminothiophenol
molecules were embedded inside the cyclodextrin cavity, lowering the vibrations of
absorption bands. Energy-dispersive X-ray spectroscopy experiments were performed to determine the content of the platinum nanoworms anchoring on the composite. The main elements which were found were Pt, C, N, O, and S, confirming
that both inclusion complex-based polymer and platinum were anchored on reduced
graphene oxide. Thermogravimetric analysis confirmed the above results. This heterogeneous catalyst had proved to be electrocatalytic active for oxygen reduction
reaction and was stable because no significant decrease of the current response was
observed after 1 week.
In 2015, pre-synthesized gold nanoparticles were adsorbed on the same composite (cyclodextrin-based polymer with reduced graphene oxide) (Chen et al. 2015).
Moreover, the surface properties were characterized by static contact angles where
the more polymer is adsorbed on reduced graphene oxide, the stronger the hydrophilicity of the composite is. The interactions of the 4-aminothiophenol and the
polymer of cyclodextrin was evaluated by UV-Vis and
1
H NMR spectroscopy. The
presence of the gold nanoparticles on the composite material was confirmed by
UV-Vis spectroscopy by the observation of one red shift of the surface plasmon
resonance of gold nanoparticles, from 522 nm to 568 nm, due to the interaction of
the 4-aminothiophenol with the particles. This interaction gave another red shift
corresponding to the thiol/amino group from 251 nm to 253 nm. Structural analyses
were also performed (X-ray diffraction and energy-dispersive X-ray spectroscopy).
The catalytic activity of these materials was evaluated in the oxygen
5 Metal Nanoparticles and Cyclodextrins for Catalytic Applications
porous structure of nickel, a large number of Au nanoparticles could be anchored on
the surface through multivalent host-guest interactions, and the reactant solution
could be catalyzed by flowing through the pores. Because of the photoisomerization
property of azobenzene, the multivalent host-guest interactions between
β-cyclodextrin and azobenzene could be removed by UV irradiation. Thus, the gold
nanoparticles could be anchored on or removed from the surface of the porous
nickel. Different electrocatalysts were prepared by increasing the gold amount.
These electrocatalysts had been evaluated in the oxygen electroreduction and compared to the unmodified electrode. The authors observed an activity enhancement
for the poly(aminothiophenol)-Au nano which can be explained by small crystallite
sizes and good distribution of gold nanoparticles on the surface of the polymer.
Platinum nanoworms self-assemble with a β-cyclodextrin polymer/reduced graphene oxide via the use of 4-aminothiophenol as nanoparticle capping agent incorporated in the cyclodextrin cavities (Gopalan et al. 2006). The cyclodextrin-based
polymer was synthesized by cross-linking β-cyclodextrin with epichlorohydrin and
the graphene oxide from natural graphite. The polymer of cyclodextrin was modified on graphene oxide, and the resulting composite was dispersed in ethanol and
mixed with polyaminothiophenol. The modified graphene oxide was reduced by
hydrazine and filtered before the addition of Pt nanoworms. The interactions of the
4-aminothiophenol and the polymer of cyclodextrin were evaluated by UV-Vis
spectroscopy and by FTIR spectroscopy. One interaction gave a red shift corresponding to the thiol/amino group from 251 nm to 256 nm. Moreover, all the characteristic peaks of 4-aminothiophenol were not observed because 4-aminothiophenol
molecules were embedded inside the cyclodextrin cavity, lowering the vibrations of
absorption bands. Energy-dispersive X-ray spectroscopy experiments were performed to determine the content of the platinum nanoworms anchoring on the composite. The main elements which were found were Pt, C, N, O, and S, confirming
that both inclusion complex-based polymer and platinum were anchored on reduced
graphene oxide. Thermogravimetric analysis confirmed the above results. This heterogeneous catalyst had proved to be electrocatalytic active for oxygen reduction
reaction and was stable because no significant decrease of the current response was
observed after 1 week.
In 2015, pre-synthesized gold nanoparticles were adsorbed on the same composite (cyclodextrin-based polymer with reduced graphene oxide) (Chen et al. 2015).
Moreover, the surface properties were characterized by static contact angles where
the more polymer is adsorbed on reduced graphene oxide, the stronger the hydrophilicity of the composite is. The interactions of the 4-aminothiophenol and the
polymer of cyclodextrin was evaluated by UV-Vis and
1
H NMR spectroscopy. The
presence of the gold nanoparticles on the composite material was confirmed by
UV-Vis spectroscopy by the observation of one red shift of the surface plasmon
resonance of gold nanoparticles, from 522 nm to 568 nm, due to the interaction of
the 4-aminothiophenol with the particles. This interaction gave another red shift
corresponding to the thiol/amino group from 251 nm to 253 nm. Structural analyses
were also performed (X-ray diffraction and energy-dispersive X-ray spectroscopy).
The catalytic activity of these materials was evaluated in the oxygen
5 Metal Nanoparticles and Cyclodextrins for Catalytic Applications