14 research outputs found
Efficient Co-Nanocrystal-Based Catalyst for Hydrogen Generation from Borohydride
Sodium
borohydride (NaBH<sub>4</sub>) has been proposed as a potential
hydrogen storage material for fuel cells, and the development of highly
active and robust catalysts for hydrolyzing NaBH<sub>4</sub> is the
key for the practical usage of NaBH<sub>4</sub> for fuel cells. Herein
we report Co-nanocrystal assembled hollow nanoparticles (Co-HNP) as
an active and robust catalyst for the hydrolysis of NaBH<sub>4</sub>. A hydrogen generation rate of 10.8 L·min<sup>–1</sup>·g<sup>–1</sup> at 25 °C was achieved by using the
Co-HNP catalyst with a low activation energy of 23.7 kJ·mol<sup>–1</sup>, which is among the best performance of reported
noble and non-noble catalysts for hydrolyzing NaBH<sub>4</sub>. Co-HNP
also showed good stability in the long term cycling tests. The mechanism
of the catalytic hydrolysis of NaBH<sub>4</sub> on Co-HNP was studied
by using <sup>1</sup>H and <sup>11</sup>B solid-state NMR, which provided
unambiguous experimental evidence of the Co–H formation. The
systematically designed NMR experiments unveiled the key role of Co-HNP
in the activation of borohydride and the subsequent transfer of H<sup>–</sup> to water for generating H<sub>2</sub> gas and helped
to distinguish various hypotheses proposed for catalytic H<sub>2</sub> generation reactions. The porous hollow nanostructure of the Co-HNP
catalyst provides large surface area and facilitates mass transfer.
The facile preparation and outstanding performance of Co-HNP enables
it as a very competitive catalyst for hydrogen production
Dual High-Resolution α‑Glucosidase and Radical Scavenging Profiling Combined with HPLC-HRMS-SPE-NMR for Identification of Minor and Major Constituents Directly from the Crude Extract of <i>Pueraria lobata</i>
The crude methanol extract of <i>Pueraria lobata</i> was
investigated by dual high-resolution α-glucosidase inhibition
and radical scavenging profiling combined with hyphenated HPLC-HRMS-SPE-NMR.
Direct analysis of the crude extract without preceding purification
was facilitated by combining chromatograms from two analytical-scale
HPLC separations of 120 and 600 μg on-column, respectively.
High-resolution α-glucosidase and radical scavenging profiles
were obtained after microfractionation of the eluate in 96-well microplates.
This allowed full bioactivity profiling of individual peaks in the
HPLC chromatogram of the crude methanol extract. Subsequent HPLC-HRMS-SPE-NMR
analysis allowed identification of 21 known compounds in addition
to two new compounds, i.e., 3′-methoxydaidzein 8-<i>C</i>-[α-d-apiofuranosyl-(1→6)]-β-d-glucopyranoside and 6″-<i>O</i>-malonyl-3′-methoxydaidzin,
as well as an unstable compound tentatively identified as 3′-de-<i>O</i>-methylpuerariafuran
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors
Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission
Inspired by the reverse thrust generated by fuel injection,
micromachines
that are self-propelled by bubble ejection are developed, such as
microrods, microtubes, and microspheres. However, controlling bubble
ejection sites to build micromachines with programmable actuation
and further enabling mechanical transmission remain challenging. Here,
bubble-propelled mechanical microsystems are constructed by proposing
a multimaterial femtosecond laser processing method, consisting of
direct laser writing and selective laser metal reduction. The polymer
frame of the microsystems is first printed, followed by the deposition
of catalytic platinum into the desired local site of the microsystems
by laser reduction. With this method, a variety of designable microrotors
with selective bubble ejection sites are realized, which enable excellent
mechanical transmission systems composed of single and multiple mechanical
components, including a coupler, a crank slider, and a crank rocker
system. We believe the presented bubble-propelled mechanical microsystems
could be extended to applications in microrobotics, microfluidics,
and microsensors