10 research outputs found
DataSheet1_The applicability of sunshine-based global solar radiation models modified with meteorological factors for different climate zones of China.docx
With the development of renewable energy, the exploitation and utilization of solar energy resources also need continuous progress, but solar radiation data shortage has become a serious concern. A method for estimating global solar radiation has been developed to address this issue. The sunshine-based model is currently the most widely used model due to its high calculation accuracy and few input parameters. This paper will first review 13 subcategories (8 categories in total) of the global solar radiation prediction model based on sunshine. Subsequently, the astronomical factors were introduced to modify empirical coefficients, and 8 new categories of models based on sunshine rate were introduced. The radiation data from 83 meteorological stations in China was used to train and validate the model, and the performance of the model was evaluated by using evaluation indicators, such as coefficient of determination (R2), root mean square error (RMSE), mean absolute bias error (MABE), mean bias error (MBE), and global performance index (GPI). The results show that the R2 value of the unmodified empirical model is in a range of 0.82–0.99, and the RMSE value is in a range of 0.018–3.09. In contrast, with the introduction of the astronomical factor, the model accuracy improves significantly, and the modified power function model (N3) gains its best performance. The R2 of model N3 is in a range of 0.86–0.99, and the RMSE value is in a range of 0.018–2.62. The R2 increases by 0.49%, while the RMSE value 6.44%. Above all, it does not require the input of other meteorological parameters for predicting the value of global solar radiation.</p
Precisely Designed Mesoscopic Titania for High-Volumetric-Density Pseudocapacitance
Surface redox pseudocapacitance,
which enables short charging times
and high power delivery, is very attractive in a wide range of sites.
To achieve maximized specific capacity, nanostructuring of active
materials with high surface area is indispensable. However, one key
limitation for capacitive materials is their low volumetric capacity
due to the low tap density of nanomaterials. Here, we present a promising
mesoscale TiO2 structure with precisely controlled mesoporous
frameworks as a high-density pseudocapacitive model system. The dense-packed
mesoscopic TiO2 in micrometer size offers a high accessible
surface area (124 m2 g–1) and radially
aligned mesopore channels, but high tap density (1.7 g cm–3) that is much higher than TiO2 nanoparticles (0.47 g
cm–3). As a pseudocapacitive sodium-ion storage
anode, the precisely designed mesoscopic TiO2 model achieved
maximized gravimetric capacity (240 mAh g–1) and
volumetric capacity (350 mAh cm–3) at 0.025 A g–1. Such a designed pseudocapacitive mesostructure further
realized a commercially comparable areal capacity (2.1 mAh cm–2) at a high mass loading of 9.47 mg cm–2. This mesostructured electrode that enables fast sodiation in dense
nanostructures has implications for high-power applications, fast-charging
devices, and pseudocapacitive electrode design
Stepwise Monomicelle Assembly for Highly Ordered Mesoporous TiO<sub>2</sub> Membranes with Precisely Tailored Mesophase and Porosity
Mesoporous materials with crystalline frameworks have
been acknowledged
as very attractive materials in various applications. Nevertheless,
due to the cracking issue during crystallization and incompatible
hydrolysis and assembly, the precise control for crystalline mesoscale
membranes is quite infertile. Herein, we presented an ingenious stepwise
monomicelle assembly route for the syntheses of highly ordered mesoporous
crystalline TiO2 membranes with delicately controlled mesophase,
mesoporosity, and thickness. Such a process involves the preparation
of monomicelle hydrogels and follows self-assembly by stepwise solvent
evaporation, which enables the sensitive hydrolysis of TiO2 oligomers and dilatory micelle assembly to be united. In consequence,
the fabricated mesoporous TiO2 membranes exhibit a broad
flexibility, including tunable ordered mesophases (worm-like, hexagonal p6mm to body-centered cubic Im3̅m), controlled mesopore sizes (3.0–8.0 nm), and anatase grain
sizes (2.3–8.4 nm). Besides, such mesostructured crystalline
TiO2 membranes can be extended to diverse substrates (Ti,
Ag, Si, FTO) with tailored thickness. The great mesoporosity of the in situ fabricated mesoscopic membranes also affords excellent
pseudocapacitive behavior for sodium ion storage. This study underscores
a novel pathway for balancing the interaction of precursors and micelles,
which could have implications for synthesizing crystalline mesostructures
in higher controllability
Two-Dimensional Mesoporous Heterostructure Delivering Superior Pseudocapacitive Sodium Storage via Bottom-Up Monomicelle Assembly
Two-dimensional
(2D) heterostructures endowed with mesoporosities
offer exciting opportunities in electrocatalysis, photocatalysis,
energy storage, and conversion technologies due to their integrated
functionalities, abundant active sites and shortened diffusion distance.
However, layered mesostructures have not been combined due to the
immense difficulties by conventional chemical, mechanical exfoliation
or self-assembly approaches. Herein, we explore a bottom-up strategy,
carried out under mild conditions, for the facile synthesis of monolayered
mesoporous-titania–mesoporous-carbon vertical heterostructure
with uniform mesopore size, which enables ultrahigh rate capability
and cycling longevity for pseudocapacitive sodium-ion storage in nonaqueous
electrolyte. Such a brand-new type of heterostructure consists of
well-ordered monolayered mesoporous titania nanosheets and surrounding
two mesoporous carbon monolayers assembled at both sides. Remarkably,
the combination of interconnected large mesoporosity and heterointerface
leads to highly promoted reversible pseudocapacitance (96.4% of total
charge storage at a sweep rate of 1 mV s–1), and
it enables the material to retain strong mechanical stability during
the rapid sodiation and desodiation processes. This study reveals
the importance of incorporating mesopores into heterointerface as
a strategy for enhancing charge storage kinetics of electroactive
materials
Mesoporous TiO<sub>2</sub> Single-Crystal Particles from Controlled Crystallization-Driven Mono-Micelle Assembly as an Efficient Photocatalyst
Mesoporous
materials with crystalline frameworks have been widely
explored in many fields due to their unique structure and crystalline
feature, but accurate manipulations over crystalline scaffolds, mainly
composed of uncontrolled polymorphs, are still lacking. Herein, we
explored a controlled crystallization-driven monomicelle assembly
approach to construct a type of uniform mesoporous TiO2 particles with atomically aligned single-crystal frameworks. The
resultant mesoporous TiO2 single-crystal particles possess
an angular shape ∼80 nm in diameter, good mesoporosity (a high
surface area of 112 m2 g–1 and a mean
pore size at 8.3 nm), and highly oriented anatase frameworks. By adjusting
the evaporation rate during assembly, such a facile solution-processed
strategy further enables the regulation of the particle size and mesopore
size without the destruction of the oriented crystallites. Such a
combination of ordered mesoporosity and crystalline orientation provides
both effective mass and charge transportation, leading to a significant
increase in the hydrogen generation rate. A maximum hydrogen evolution
rate of 12.5 mmol g–1 h–1 can
be realized, along with great stability under solar light. Our study
is envisaged to extend the possibility of mesoporous single crystal
growth to a range of functional ceramics and semiconductors toward
advanced applications
Uniform Ordered Two-Dimensional Mesoporous TiO<sub>2</sub> Nanosheets from Hydrothermal-Induced Solvent-Confined Monomicelle Assembly
Two-dimensional
(2D) nanomaterials have been the focus of substantial
research interest recently owing to their fascinating and excellent
properties. However, 2D porous materials have remained quite rare
due to the difficulty of creating pores in 2D nanostructures. Here,
we have synthesized a novel type of single-layered 2D mesoporous TiO<sub>2</sub> nanosheets with very uniform size and thickness as well as
ordered mesostructure from an unprecedented hydrothermal-induced solvent-confined
assembly approach. The F127/TiO<sub>2</sub> spherical monomicelles
are first formed and redispersed in ethanol and glycerol, followed
by a hydrothermal treatment to assemble these subunits into single-layered
2D mesostructure owing to the confinement effect of highly adhered
glycerol solvent. The obtained 2D mesoporous TiO<sub>2</sub> nanosheets
have a relative mean size at around 500 × 500 nm and can be randomly
stacked into a bulk. The TiO<sub>2</sub> nanosheets possess only one
layer of ordered mesopores with a pore size of 4.0 nm, a very high
surface area of 210 m<sup>2</sup> g<sup>–1</sup> and a uniform
thickness of 5.5 nm. The thickness can be further manipulated from
5.5 to 27.6 nm via simply tuning precursor concentration or solvent
ratio. Due to the well-defined 2D morphology and large mesoporosity
as well as crystalline anatase mesopore walls, these uniform TiO<sub>2</sub> nanosheets are capable of providing large accessible voids
for sodium ion adsorption and intercalation as well as preventing
volume expansion. As expected, these mesoporous TiO<sub>2</sub> nanosheets
have exhibited an excellent reversible capacity of 220 mAh g<sup>–1</sup> at 100 mA g<sup>–1</sup> as sodium-ion battery anodes, and
they can retain at 199 mAh g<sup>–1</sup> after numerous cycles
at different current densities. The capacity is retained at 44 mAh
g<sup>–1</sup> even at a large current density of 10 A g<sup>–1</sup> after 10 000 cycles, demonstrating a remarkable
performance for energy storage
Constructing Three-Dimensional Mesoporous Bouquet-Posy-like TiO<sub>2</sub> Superstructures with Radially Oriented Mesochannels and Single-Crystal Walls
Constructing three-dimensional (3-D)
hierarchical mesostructures
with unique morphology, pore orientation, single-crystal nature, and
functionality remains a great challenge in materials science. Here,
we report a confined microemulsion self-assembly approach to synthesize
an unprecedented type of 3-D highly ordered mesoporous TiO<sub>2</sub> superstructure (Level-1), which consists of 1 spherical core and
12 symmetric satellite hemispheres epitaxially growing out of the
core vertices. A more complex and asymmetric TiO<sub>2</sub> superstructure
(Level-2) with 13 spherical cores and up to 44 symmetric satellite
hemispheres can also be well manipulated by increasing the size or
content of impregnated TiO<sub>2</sub> precursor emulsion droplets.
The obtained 3-D mesoporous TiO<sub>2</sub> superstructures have well-defined
bouquet-posy-like topologies, oriented hexagonal mesochannels, high
accessible surface area (134–148 m<sup>2</sup>/g), large pore
volume (0.48–0.51 cm<sup>3</sup>/g), and well single-crystalline
anatase walls with dominant (001) active facets. More interestingly,
all cylindrical mesopore channels are highly interconnected and radially
distributed within the whole superstructures, and all TiO<sub>2</sub> nanocrystal building blocks are oriented grown into a single-crystal
anatase wall, making them ideal candidates for various applications
ranging from catalysis to optoelectronics. As expected, the bouquet-posy-like
mesoporous TiO<sub>2</sub> superstructure supported catalysts show
excellent catalytic activity (≥99.7%) and selectivity (≥96%)
in <i>cis</i>-semihydrogenation of various alkynes, exceeding
that of commercial TiO<sub>2</sub> (P25) supported catalyst by a factor
of 10. No decay in the activity was observed for 25 cycles, revealing
a high stability of the mesoporous TiO<sub>2</sub> superstructure
supported catalyst
Constructing Unique Mesoporous Carbon Superstructures via Monomicelle Interface Confined Assembly
Constructing
hierarchical three-dimensional (3D) mesostructures
with unique pore structure, controllable morphology, highly accessible
surface area, and appealing functionality remains a great challenge
in materials science. Here, we report a monomicelle interface confined
assembly approach to fabricate an unprecedented type of 3D mesoporous
N-doped carbon superstructure for the first time. In this hierarchical
structure, a large hollow locates in the center (∼300 nm in
diameter), and an ultrathin monolayer of spherical mesopores (∼22
nm) uniformly distributes on the hollow shells. Meanwhile, a small
hole (4.0–4.5 nm) is also created on the interior surface of
each small spherical mesopore, enabling the superstructure to be totally
interconnected. Vitally, such interconnected porous supraparticles
exhibit ultrahigh accessible surface area (685 m2 g–1) and good underwater aerophilicity due to the abundant
spherical mesopores. Additionally, the number (70–150) of spherical
mesopores, particle size (22 and 42 nm), and shell thickness (4.0–26
nm) of the supraparticles can all be accurately manipulated. Besides
this spherical morphology, other configurations involving 3D hollow
nanovesicles and 2D nanosheets were also obtained. Finally, we manifest
the mesoporous carbon superstructure as an advanced electrocatalytic
material with a half-wave potential of 0.82 V (vs RHE), equivalent
to the value of the commercial Pt/C electrode, and notable durability
for oxygen reduction reaction (ORR)
Mesoporous TiO<sub>2</sub> Mesocrystals: Remarkable Defects-Induced Crystallite-Interface Reactivity and Their in Situ Conversion to Single Crystals
Oriented
self-assembly between inorganic nanocrystals and surfactants is emerging
as a route for obtaining new mesocrystalline semiconductors. However,
the actual synthesis of mesoporous semiconductor mesocrystals with
abundant surface sites is extremely difficult, and the corresponding
new physical and chemical properties arising from such an intrinsic
porous mesocrystalline nature, which is of fundamental importance
for designing high-efficiency nanostructured devices, have been rarely
explored and poorly understood. Herein, we report a simple evaporation-driven
oriented assembly method to grow unprecedented olive-shaped mesoporous
TiO<sub>2</sub> mesocrystals (FDU-19) self-organized by ultrathin
flake-like anatase nanocrystals (∼8 nm in thickness). The mesoporous
mesocrystals FDU-19 exhibit an ultrahigh surface area (∼189
m<sup>2</sup>/g), large internal pore volume (0.56 cm<sup>3</sup>/g),
and abundant defects (oxygen vacancies or unsaturated Ti<sup>3+</sup> sites), inducing remarkable crystallite-interface reactivity. It
is found that the mesocrystals FDU-19 can be easily fused in situ
into mesoporous anatase single crystals (SC-FDU-19) by annealing in
air. More significantly, by annealing in a vacuum (∼4.0 ×
10<sup>–5</sup> Pa), the mesocrystals experience an abrupt
three-dimensional to two-dimensional structural transformation to
form ultrathin anatase single-crystal nanosheets (NS-FDU-19, ∼8
nm in thickness) dominated by nearly 90% exposed reactive (001) facets.
The balance between attraction and electrostatic repulsion is proposed
to determine the resulting geometry and dimensionality. Dye-sensitized
solar cells based on FDU-19 and SC-FDU-19 samples show ultrahigh photoconversion
efficiencies of up to 11.6% and 11.3%, respectively, which are largely
attributed to their intrinsic single-crystal nature as well as high
porosity. This work gives new understanding of physical and chemical
properties of mesoporous semiconductor mesocrystals and opens up a
new pathway for designing various single-crystal semiconductors with
desired mesostructures for applications in catalysis, sensors, drug
delivery, optical devices, etc
Mesoporous TiO<sub>2</sub> Mesocrystals: Remarkable Defects-Induced Crystallite-Interface Reactivity and Their in Situ Conversion to Single Crystals
Oriented
self-assembly between inorganic nanocrystals and surfactants is emerging
as a route for obtaining new mesocrystalline semiconductors. However,
the actual synthesis of mesoporous semiconductor mesocrystals with
abundant surface sites is extremely difficult, and the corresponding
new physical and chemical properties arising from such an intrinsic
porous mesocrystalline nature, which is of fundamental importance
for designing high-efficiency nanostructured devices, have been rarely
explored and poorly understood. Herein, we report a simple evaporation-driven
oriented assembly method to grow unprecedented olive-shaped mesoporous
TiO<sub>2</sub> mesocrystals (FDU-19) self-organized by ultrathin
flake-like anatase nanocrystals (∼8 nm in thickness). The mesoporous
mesocrystals FDU-19 exhibit an ultrahigh surface area (∼189
m<sup>2</sup>/g), large internal pore volume (0.56 cm<sup>3</sup>/g),
and abundant defects (oxygen vacancies or unsaturated Ti<sup>3+</sup> sites), inducing remarkable crystallite-interface reactivity. It
is found that the mesocrystals FDU-19 can be easily fused in situ
into mesoporous anatase single crystals (SC-FDU-19) by annealing in
air. More significantly, by annealing in a vacuum (∼4.0 ×
10<sup>–5</sup> Pa), the mesocrystals experience an abrupt
three-dimensional to two-dimensional structural transformation to
form ultrathin anatase single-crystal nanosheets (NS-FDU-19, ∼8
nm in thickness) dominated by nearly 90% exposed reactive (001) facets.
The balance between attraction and electrostatic repulsion is proposed
to determine the resulting geometry and dimensionality. Dye-sensitized
solar cells based on FDU-19 and SC-FDU-19 samples show ultrahigh photoconversion
efficiencies of up to 11.6% and 11.3%, respectively, which are largely
attributed to their intrinsic single-crystal nature as well as high
porosity. This work gives new understanding of physical and chemical
properties of mesoporous semiconductor mesocrystals and opens up a
new pathway for designing various single-crystal semiconductors with
desired mesostructures for applications in catalysis, sensors, drug
delivery, optical devices, etc
