6 research outputs found
Three-Dimensional FTO/TiO<sub>2</sub>/BiVO<sub>4</sub> Composite Inverse Opals Photoanode with Excellent Photoelectrochemical Performance
A poor electron transport property, short charge carrier diffusion
lengths, and slow water oxidation kinetics severely limit the photoelectrochemical
(PEC) performance of the BiVO<sub>4</sub> photoelectrodes. To address
these problems, we report the design and fabrication of a three-dimensional
FTO/TiO<sub>2</sub>/BiVO<sub>4</sub> core–shell inverse opals
photoanode for PEC hydrogen production by combining atomic layer deposition
and electrodeposition routes for TiO<sub>2</sub> and BiVO<sub>4</sub> layer deposition on F:SnO<sub>2</sub> (FTO) inverse opal skeletons,
respectively. Benefiting from the highly conductive transparent FTO
invese opal networks providing fast electron pathways and TiO<sub>2</sub>/BiVO<sub>4</sub> heterojunctions, the as-fabricated 3D FTO/TiO<sub>2</sub>/BiVO<sub>4</sub> inverse opals photoanode delivers excellent
PEC performance with a maximum photocurrent density of 4.11 mA/cm<sup>2</sup> at 1.23 V vs a reversible hydrogen electrode in the presence
of a hole scavenger in contrast to that of the counterparts FTO/TiO<sub>2</sub> and FTO/BiVO<sub>4</sub> inverse opals electrodes, respectively,
which could be attributed to the significantly improved charge transport
and separation efficiency
ALD TiO<sub>2</sub>‑Coated Flower-like MoS<sub>2</sub> Nanosheets on Carbon Cloth as Sodium Ion Battery Anode with Enhanced Cycling Stability and Rate Capability
We report the fabrication
of 3D flower-like MoS<sub>2</sub> nanosheets arrays on carbon cloth
as a binder-free anode for sodium ion battery. Ultrathin and conformal
TiO<sub>2</sub> layers are used to modify the surface of MoS<sub>2</sub> by atomic layer deposition. The electrochemical performance measurements
demonstrate that the ALD TiO<sub>2</sub> layer can improve the cycling
stability and rate capability of MoS<sub>2</sub>. The MoS<sub>2</sub> nanosheets with 0.5-nm TiO<sub>2</sub> coating electrode show the
highest initial discharge capacity of 1392 mA h g<sup>–1</sup> at 200 mA g<sup>–1</sup>, which is increased by 53% compared
with that of bare MoS<sub>2</sub>. After 150 cycles, the capacity
retention rate of the TiO<sub>2</sub>-coated MoS<sub>2</sub> achieves
75.8% of its second cycle’s capacity at 200 mA h g<sup>–1</sup> in contrast to that of 59% of pure MoS<sub>2</sub>. Furthermore,
the mechanism behind the experimental results is revealed by ex situ
scanning electron microscope (SEM), X-ray powder diffraction (XRD),
and electrochemical impedance spectroscopy (EIS) characterizations,
which confirms that the ultrathin TiO<sub>2</sub> modifications can
prevent the structural degradation and the formation of SEI film of
MoS<sub>2</sub> electrode
Three-Dimensional CdS-Sensitized Sea Urchin Like TiO<sub>2</sub>‑Ordered Arrays as Efficient Photoelectrochemical Anodes
We demonstrate the fabrication of
a 3D ordered sea urchin like
TiO<sub>2</sub> structure by combining colloidal spheres template,
atomic layer deposition (ALD), and hydrothermal growth method. The
3D sea urchin like TiO<sub>2</sub> arrays as photoanode present improved
photoelectrochemical performance in contrast to 2D TiO<sub>2</sub> hollow microspheres and 1D TiO<sub>2</sub> nanowires arrays. With
CdS quantum dots sensitization, the sea urchin like TiO<sub>2</sub> array photoanode yields a photocurrent of 5.4 mA cm<sup>–2</sup> at 0 V vs Ag/AgCl. The performance improvement is attributed to
the increased specific surface area and porosity, light trapping effect
by multiscattering of the hierarchical structure, as well as direct
charge transportation paths from the nanorods to the microspheres
Three-dimensional Ordered Macroporous Flexible Electrode Design toward High-Performance Zinc-Ion Batteries
Flexible
zinc-ion batteries (ZIBs) have been considered to have
huge potential in portable and wearable electronics due to their high
safety, cost efficiency, and considerable energy density. Therein,
the design and construction of flexible electrodes significantly determine
the performance and lifespan of flexible battery devices. In this
work, an ultrathin flexible three-dimensional ordered macroporous
(3DOM) Sn@Zn anode (60 μm in thickness) is presented to relieve
dendrite growth and expand the lifespan of flexible ZIBs. The 3DOM
structure can ensure uniform electric field distribution, guide oriented
zinc plating/stripping, and extend the lifespan of anodes. The rich
zincophilic Sn sites on the electrode surface significantly facilitate
Zn nucleation. Accordingly, a lowered nucleation overpotential of
8.9 mV and an ultralong cycling performance of 2400 h at 0.1 mA cm–2 and 0.1 mAh cm–2 are achieved in
symmetric cells, and the 3DOM Sn@Zn anode can also operate in deep
cycling for over 200 h at 10 mA cm–2 and 5 mAh cm–2. A flexible 3DOM MnO2/Ni cathode with
a high structural stability and a high mass-specific capacity is fabricated
to match with the anode to form a flexible ZIB with a total thickness
of 200 μm. The flexible device delivers a high volumetric energy
density of 11.76 mWh cm–3 at 100 mA gMnO2–1 and a high average open-circuit voltage of 1.5
V and exhibits high-performance power supply under deformation in
practical application scenarios. This work may shed some light on
the design and fabrication of flexible energy-storage devices
Three-Dimensional NiCo<sub>2</sub>O<sub>4</sub>@Polypyrrole Coaxial Nanowire Arrays on Carbon Textiles for High-Performance Flexible Asymmetric Solid-State Supercapacitor
In this article, we report a novel
electrode of NiCo<sub>2</sub>O<sub>4</sub> nanowire arrays (NWAs)
on carbon textiles with a polypyrrole (PPy) nanosphere shell layer
to enhance the pseudocapacitive performance. The merits of highly
conductive PPy and short ion transport channels in ordered NiCo<sub>2</sub>O<sub>4</sub> mesoporous nanowire arrays together with the
synergistic effect between NiCo<sub>2</sub>O<sub>4</sub> and PPy result
in a high specific capacitance of 2244 F g<sup>–1</sup>, excellent
rate capability, and cycling stability in NiCo<sub>2</sub>O<sub>4</sub>/PPy electrode. Moreover, a lightweight and flexible asymmetric supercapacitor
(ASC) device is successfully assembled using the hybrid NiCo<sub>2</sub>O<sub>4</sub>@PPy NWAs and activated carbon (AC) as electrodes, achieving
high energy density (58.8 W h kg<sup>–1</sup> at 365 W kg<sup>–1</sup>), outstanding power density (10.2 kW kg<sup>–1</sup> at 28.4 W h kg<sup>–1</sup>) and excellent cycling stability
(∼89.2% retention after 5000 cycles), as well as high flexibility.
The three-dimensional coaxial architecture design opens up new opportunities
to fabricate a high-performance flexible supercapacitor for future
portable and wearable electronic devices
Composition-Graded Zn<sub><i>x</i></sub>Cd<sub><sub>1–<i>x</i></sub></sub>Se@ZnO Core–Shell Nanowire Array Electrodes for Photoelectrochemical Hydrogen Generation
One-dimensional oxide nanostructure arrays are widely
investigated
as photoelectrodes in solar cells or photoelectrochemical (PEC) solar
hydrogen generation applications, for which it is highly desirable
for the electrode to have a broad light absorption and an efficient
charge separation. In this work, a composition-graded Zn<sub><i>x</i></sub>Cd<sub>1–<i>x</i></sub>Se@ZnO core–shell
nanowire array is prepared through temperature-gradient chemical
vapor deposition (CVD) of Zn<sub><i>x</i></sub>Cd<sub>1–<i>x</i></sub>Se layer
onto the pregrown ZnO nanowires. The core–shell nanowire array
photoelectrodes yield a continuous absorption edge
from 2.7 (460 nm) to 1.77 eV (700 nm) across the sample surface. The
core–shell
heterostructure facilitates the photogenerated electron–hole
pair separation and the electron transfer from ZnCdSe to ZnO. By
using such core–shell nanowire arrays as photoanodes for solar
hydrogen generation via
a PEC cell, a photocurrent density of ∼5.6 mA/cm<sup>2</sup> is achieved under 1 sun solar light illumination at zero bias versus
Ag/AgCl. This method may be useful in the design of multijunction
nanostructured semiconductor photoelectrodes toward more efficient
solar fuel devices