As crystalline semiconductor nanowires
are thinned down to a single-unit-cell
thickness, many fascinating properties could arise pointing to promising
applications in various fields. A grand challenge is to be able to
controllably synthesize such ultrathin nanowires. Herein, we report
a strategy, which synergizes a soft template with oriented attachment
(ST-OA), to prepare high-quality single-unit-cell semiconductor nanowires
(SSNWs). Using this protocol, we are able to synthesize for the first
time ZnS and ZnSe nanowires (NWs) with only a single-unit-cell thickness
(less than 1.0 nm) and a cluster-like absorption feature (i.e., with
a sharp, strong, and significantly blue-shifted absorption peak).
Particularly, the growth mechanism and the single-unit-cell structure
of the as-prepared ZnS SSNWs are firmly established by both experimental
observations and theoretical calculations. Thanks to falling into
the extreme quantum confinement regime, these NWs are found to only
absorb the light with wavelengths shorter than 280 nm (i.e., solar-blind
UV absorption). Utilizing such a unique property, self-powered photoelectrochemical-type
photodetectors (PEC PDs) based on the ZnS SSNWs are successfully fabricated.
The PDs after interface modification with TiO2 exhibit
an excellent solar-blind UV photoresponse performance, with a typical
on/off ratio of 6008, a detectivity of 1.5 × 1012 Jones,
and a responsivity of 33.7 mA/W. This work opens the door to synthesizing
and investigating a new dimension of nanomaterials with a wide range
of applications.
Localized
surface plasmon resonance (LSPR) is well known for its
unique ability to tune the reactivity of plasmonic materials via photoexcitation;
however, it is still an open question as to whether plasmonic holes
can be directly extracted to drive valuable chemical reactions. Herein
we give an affirmative answer by reporting an illumination-enhanced
oxygen evolution reaction (OER) using CuS nanodisks (NDs) alone as
the electrocatalyst. Impressively, under 1221 nm laser or xenon lamp
illumination, an unprecedented reduction of OER overpotential was
observed on the CuS ND-coated electrodes. Transient absorption combined
with Mott–Schottky measurements disclosed that near-infrared
(NIR) irradiation generated abundant hot holes from LSPR damping in
the CuS NDs accounting for the remarkable OER performance enhancement.
This is the first report on the direct utilization of plasmonic hot
holes in CuS nanomaterials for boosting OER performance, opening up
a new route to designing NIR-active photocatalysts/electrocatalysts
by exploiting the unique LSPR properties.
We report herein a heat-triggered precursor slow releasing route for the one-pot synthesis of ultrathin ZnSe nanowires (NWs), which relies on the gradual dissolving of Se powder into oleylamine containing a soluble Zn precursor under heating. This route allows the reaction system to maintain a high monomer concentration throughout the entire reaction process, thus enabling the generation of ZnSe NWs with diameter down to 2.1 nm and length approaching 400 nm. The size-dependent optical properties and band-edge energy levels of the ZnSe NWs were then explored in depth by UV-visible spectroscopy and cyclic voltammetry, respectively. Considering their unique absorption properties, these NWs were specially utilized for fabricating photoelectrochemical-type photodetectors (PDs). Impressively, the PDs based on the ZnSe NWs with diameters of 2.1 and 4.5 nm exhibited excellent responses to UVA and near-visible light, respectively: both possessed ultrahigh on/off ratios (5150 for UVA and 4213 for near-visible light) and ultrawide linear response ranges (from 2.0 to 9000 μW cm for UVA and 5.0 to 8000 μW cm for near-visible light). Furthermore, these ZnSe NWs were selectively doped with various amounts of Mn to tune their emission properties. As a result, ZnSe NW film-based photochromic cards were creatively developed for visually detecting UVA and near-visible radiation.
In this work, we report on the synthesis of nitrogen doped SrTiO3 nanoparticles with efficient visible light driven photocatalytic activity toward Cr(VI) by the solvothermal method. The samples are carefully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy and photocatalytic test. It is found that nitrogen doping in SrTiO3 lattice led to an apparent lattice expansion, particle size reduction as well as subsequent increase of Brunner–Emmet–Teller surface area. The visible light absorption edge and intensity can be modulated by nitrogen doping content, which absorption edge extends to about 600 nm. Moreover, nitrogen doping can not only modulate the visible light absorption feature, but also have consequence on the enhancement of charge separation efficiency, which can promote the photocatalytic activity. With well controlled particle size, Brunner–Emmet–Teller surface area, and electronic structure via nitrogen doping, the photocatalytic performance toward Cr(VI) reduction of nitrogen doped SrTiO3 was optimized at initial hexamethylenetetramine content of 2.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2804-2) contains supplementary material, which is available to authorized users.
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