6 research outputs found
In Situ Monitored Self-Assembly of Three-Dimensional Polyhedral Nanostructures
The self-assembly of 3D nanostructures
is a promising technology
for the fabrication of next generation nanodevices and the exploration
of novel phenomena. However, the present techniques for assembly of
3D nanostructures are invisible and have to be done without physical
contact, which bring great challenges in controlling the shapes with
nanoscale precision. This situation leads to an extremely low yield
of self-assembly, especially in 3D nanostructures built with metal
and semiconductor materials. Here, an in situ self-assembly process
using a focused ion beam (FIB) microscopy system has been demonstrated
to realize 3D polyhedral nanostructures from 2D multiple pieces. An
excited ion beam in the FIB microscopy system offers not only a visualization
of the nanoscale self-assembly process but also the necessary energy
for inducing the process. Because the beam energy that induces the
self-assembly can be precisely adjusted while monitoring the status
of the self-assembly, it is possible to control the self-assembly
process with sub-10 nm scale precision, resulting in the realization
of diverse 3D nanoarchitectures with a high yield. This approach will
lead to state-of-the-art applications utilizing properties of 3D nanostructures
in diverse fields
Improved Charge Separation and CO<sub>2</sub> Affinity of In<sub>2</sub>O<sub>3</sub> by K Doping with Accompanying Oxygen Vacancies for Boosted CO<sub>2</sub> Photoreduction
The
CO2 photocatalytic conversion efficiency of the
semiconductor photocatalyst is always inhibited by the sluggish charge
transfer and undesirable CO2 affinity. In this work, we
prepare a series of K-doped In2O3 catalysts
with concomitant oxygen vacancies (OV) via a hydrothermal
method, followed by a low-temperature sintering treatment. Owing to
the synergistic effect of K doping and OV, the charge separation
and CO2 affinity of In2O3 are synchronously
promoted. Particularly, when P/P0 = 0.010, at room temperature, the CO2 adsorption
capacity of the optimal K-doped In2O3 (KIO-3)
is 2336 cm3·g–1, reaching about
6000 times higher than that of In2O3 (0.39 cm3·g–1). As a result, in the absence
of a cocatalyst or sacrificial agent, KIO-3 exhibits a CO evolution
rate of 3.97 μmol·g–1·h–1 in a gas–solid reaction system, which is 7.6 times that of
pristine In2O3 (0.52 μmol·g–1·h–1). This study provides a novel approach
to the design and development of efficient photocatalysts for CO2 conversion by element doping
Silole-Containing Polymer Nanodot: An Aqueous Low-Potential Electrochemiluminescence Emitter for Biosensing
A novel
D–A conjugated polymer backbone containing silole
and 9-octyl-9<i>H</i>-carbazole units was synthesized via
Sonogashira reaction. This silole-containing polymer (SCP) was further
used to prepare SCP dots with a nanoprecipitation method, which showed
an electrochemiluminescence (ECL) emission at relatively low potential
in aqueous solution. The strong anodic ECL emission could be observed
at +0.4 V (vs Ag/AgCl) with a peak value at +0.78 V in the presence
of tri-n-propylamine (TPrA) as a co-reactant, which came from the
band gap emission of the excited SCP dots. The ECL emission could
be quenched via resonance energy transfer from the excited SCP dots
to an acceptor. Thus, a low-potential anodic ECL sensing strategy
was proposed for ECL detection of the acceptor-related analytes. Using
dopamine as the analyte, whose electro-oxidation product could act
as the energy acceptor to quench the ECL emission of SCP dots, the
ECL detection method showed a detection limit of 50 nM and high anti-interference
ability. This work demonstrates an example of polymer dots as an ECL
emitter and its potential application in ECL detection methodology
Friedel–Crafts Amidoalkylation via Thermolysis and Oxidative Photocatalysis
Friedel–Crafts amidoalkylation was achieved by
oxidation
of dialkylamides using persulfate (S<sub>2</sub>O<sub>8</sub><sup>2–</sup>) in the presence of the visible light catalyst, RuÂ(bpy)<sub>3</sub>Cl<sub>2</sub>, at room temperature, via a reactive <i>N</i>-acyliminium intermediate. Alternatively, mild heating
of the dialkylamides and persulfate afforded a metal and Lewis acid-free
Friedel–Crafts amidoalkylation. Alcohols and electron-rich
arenes served as effective nucleophiles, forming new C–O or
C–C bonds. In general, photocatalysis provided higher yields
and better selectivities
Light-Mediated Reductive Debromination of Unactivated Alkyl and Aryl Bromides
Cleavage
of carbon–halogen bonds via either single-electron reduction
or atom transfer is a powerful transformation in the construction
of complex molecules. In particular, mild, selective hydrodehalogenations
provide an excellent follow-up to the application of halogen atoms
as directing groups or the utilization of atom transfer radical addition
(ATRA) chemistry for the production of hydrocarbons. Here we combine
the mechanistic properties of photoredox catalysis and silane-mediated
atom transfer chemistry to accomplish the hydrodebromination of carbon–bromide
bonds. The resulting method is performed under visible light irradiation
in an open vessel and is capable of the efficient reduction of a variety
of unactivated alkyl and aryl substrates
Construction of BiOIO<sub>3</sub>/AgIO<sub>3</sub> Z‑Scheme Photocatalysts for the Efficient Removal of Persistent Organic Pollutants under Natural Sunlight Illumination
The efficient removal of persistent
organic pollutants
(POPs) in
natural waters is vital for human survival and sustainable development.
Photocatalytic degradation is a feasible and cost-effective strategy
to completely disintegrate POPs at room temperature. Herein, we develop
a series of direct Z-scheme BiOIO3/AgIO3 hybrid
photocatalysts via a facile deposition–precipitation method.
Under natural sunlight irradiation, the light intensity of which is
∼40 mW/cm2, a considerable rate constant of 0.185
min–1 for photodecomposing 40 mg/L MO is obtained
over 0.5 g/L Bi@Ag-5 composite photocatalyst powder, about 92.5 and
5.3 times higher than those of pristine AgIO3 and BiOIO3. The photoactivity of Bi@Ag-5 for photodecomposing MO under
natural sunlight illumination surpasses most of the reported photocatalysts
under Xe lamp illumination. After natural sunlight irradiation for
20 min, 95% of MO, 82% of phenol, 78% of 2,4-DCP, 54% of ofloxacin,
and 88% of tetracycline hydrochloride can be photodecomposed over
Bi@Ag-5. Relative to the commercial photocatalyst TiO2 (P25),
Bi@Ag-5 exhibits greatly higher photoactivity for the treatment of
MO–phenol–tetracycline hydrochloride mixture pollutants
in the scale-up experiment of 500 mL of solution, decreasing COD,
TOC, and chromaticity value by 52, 19, and 76%, respectively, after
natural sunlight irradiation for 40 min. The photodegradation process
and mechanism of MO have been systematically investigated and proposed.
This work provides an archetype for designing efficient photocatalysts
to remove POPs