In this study, large-area hexagonal-packed Si nanorod (SiNR) arrays in conjunction with Au nanoparticles (AuNPs) were fabricated for surface-enhanced Raman spectroscopy (SERS). We have achieved ultrasensitive molecular detection with high reproducibility and spatial uniformity. A finite-difference time-domain simulation suggests that a wide range of three-dimensional electric fields are generated along the surfaces of the SiNR array. With the tuning of the gap and diameter of the SiNRs, the produced long decay length (>130 nm) of the enhanced electric field makes the SERS substrate a zero-gap system for ultrasensitive detection of large biomolecules. In the detection of R6G molecules, our SERS system achieved an enhancement factor of >10 with a relative standard deviation as small as 3.9-7.2% over 30 points across the substrate. More significantly, the SERS substrate yielded ultrasensitive Raman signals on long amyloid-β fibrils at the single-fibril level, which provides promising potentials for ultrasensitive detection of amyloid aggregates that are related to Alzheimer's disease. Our study demonstrates that the SiNRs functionalized with AuNPs may serve as excellent SERS substrates in chemical and biomedical detection.
Metal‐organic frameworks (MOFs) hybridized with a conductive matrix could potentially serve as a sulfur host for lithium‐sulfur (Li‐S) battery electrodes; so far most of the previously studied hybrid structures are in the powder form or thin compact films. This study reports 3D porous MOF@carbon nanotube (CNT) networks by grafting MOFs with tailored particle size uniformly throughout a CNT sponge skeleton. Growing larger‐size MOF particles to entrap the conductive CNT network yields a mutually embedded structure with high stability, and after sulfur encapsulation, it shows an initial discharge capacity of ≈1380 mA h g−1 (at 0.1 C) and excellent cycling stability with a very low fading rate. Furthermore, owing to the 3D porous network that is suitable for enhanced sulfur loading, a remarkable areal capacity of ≈11 mA h cm−2 (at 0.1 C) is obtained, which is much higher than other MOF‐based hybrid electrodes. The mutually embedded MOF@CNTs with simultaneously high specific capacity, areal capacity, and cycling stability represent an advanced candidate for developing high‐performance Li‐S batteries and other energy storage systems.
Lithium–sulfur
(Li–S) batteries are next-generation
energy storage systems with high energy density, and the rate performance
is a very important consideration for practical applications. Recent
approaches such as introducing catalytic materials to facilitate polysulfide
conversion have been explored, yet the results remain unsatisfactory.
Here, we present an optimized Li–S electrode featured by a
large amount of highly dispersed Co3S4 nanoparticles
(∼10 nm in size) throughout a hierarchical carbon nanostructure
hybridized from ZIF-67 and carbon nanotube (CNT) sponge. This enables
homogeneous distribution and close contact between infiltrated sulfur
and Co3S4 nanoparticles within the ZIF-67-derived
N-doped carbon nanocubes, leading to effective chemical interaction
with polysulfides, maximum catalytic effect and enhanced lithium ion
diffusion, while the built-in three-dimensional CNT network ensures
high electrical conductivity of the electrode. As a consequence, the
Li–S battery exhibits both extraordinary rate performance by
maintaining a capacity of ∼850 mAh g–1 at
very high charge/discharge rate (5 C) and long-term cycling stability
with 85% retention after 1000 cycles at 5 C (an average capacity fading
rate of only 0.0137% per cycle).
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