Photocatalytic conversion
of lignocellulose to valuable aromatics has significant potential
for applications in biorefineries. The photocatalyst efficiency of
lignocellulose conversion is typically limited by the buffering redox
system in combination with oxidation and reduction of the photoexcited
holes and electrons, respectively, which ensures high charge-recombination
rates. Herein, Ag+-exchanged CdS is employed for easy photoexcited
electron transfer to the oxidized intermediate, which results in a
marked increase in the conversion yield with high product selectivity
under mild reaction conditions without any additives. The conversion
yield of the lignin model compound under 6 W blue LED illumination
is nearly 100% and only cleaved aromatic compounds are formed. The
efficient photoredox CdS catalyst obtained via photoexcited electron–hole
coupled transfer derived from an appropriate Ag+ exchange
affords a promising method for lignocellulose conversion with reduced
energy consumption.
Thermoelectric power generation offers a promising way to recover waste heat. The geometrical design of thermoelectric legs in modules is important to ensure sustainable power generation but cannot be easily achieved by traditional fabrication processes. Herein, we propose the design of cellular thermoelectric architectures for efficient and durable power generation, realized by the extrusion-based 3D printing process of Cu2Se thermoelectric materials. We design the optimum aspect ratio of a cuboid thermoelectric leg to maximize the power output and extend this design to the mechanically stiff cellular architectures of hollow hexagonal column- and honeycomb-based thermoelectric legs. Moreover, we develop organic binder-free Cu2Se-based 3D-printing inks with desirable viscoelasticity, tailored with an additive of inorganic Se82− polyanion, fabricating the designed topologies. The computational simulation and experimental measurement demonstrate the superior power output and mechanical stiffness of the proposed cellular thermoelectric architectures to other designs, unveiling the importance of topological designs of thermoelectric legs toward higher power and longer durability.
Compared with the large plastic deformation observed in ductile metals and organic materials, inorganic semiconductors have limited plasticity (<0.2%) due to their intrinsic bonding characters, restricting their widespread applications in stretchable electronics. Herein, the solution‐processed synthesis of ductile α‐Ag2S thin films and fabrication of all‐inorganic, self‐powered, and stretchable memory devices, is reported. Molecular Ag2S complex solution is synthesized by chemical reduction of Ag2S powder, fabricating wafer‐scale highly crystalline Ag2S thin films. The thin films show stretchability due to the intrinsic ductility, sustaining the structural integrity at a tensile strain of 14.9%. Moreover, the fabricated Ag2S‐based resistive random access memory presents outstanding bipolar switching characteristics (Ion/Ioff ratio of ≈105, operational endurance of 100 cycles, and retention time >106 s) as well as excellent mechanical stretchability (no degradation of properties up to stretchability of 52%). Meanwhile, the device is highly durable under diverse chemical environments and temperatures from −196 to 300 °C, especially maintaining the properties for 168 h in 85% relative humidity and 85 °C. A self‐powered memory combined with motion sensors for use as a wearable healthcare monitoring system is demonstrated, offering the potential for designing high‐performance wearable electronics that are usable in daily life in a real‐world setting.
The recent interest
in wearable electronics suggests flexible thermoelectrics as candidates
for the power supply. Herein, we report a solution process to fabricate
flexible Sb2Te3 thermoelectric thin films using
molecular Sb2Te3 precursors, synthesized by
the reduction of Sb2Te3 powder in ethylenediamine
and ethanedithiol with superhydride. The fabricated flexible Sb2Te3 thin films exhibit a power factor of ∼8.5
μW cm–1 K−2 at 423 K, maintaining
the properties during 1000 bending cycles. FePt nanoparticles are
homogeneously embedded in the Sb2Te3 thin film,
reducing the thermal conductivity. The current study offers considerable
potential for manufacturing high-performance flexible thin film devices.
Cation-exchange-induced
phase transformations have recently been
employed for the synthesis of a variety of nanomaterials. In this
study, we induced a cation-exchange reaction by adding Bi-oleate to
PbS quantum dots (QDs) and synthesized uniform Pb1–x
Bi
x
S
y
QDs and nanorods (NRs) with a diameter of approximately 3
nm and length of 40 nm (aspect ratio 1:5), respectively. Colloidal
QDs are promising materials for thermoelectric applications owing
to their simple production process, easy dimensional control, low
thermal conductivity, and high Seebeck coefficient. We studied the
thermoelectric properties of Pb1–x
Bi
x
S
y
QDs
and NRs synthesized through cation exchange. The Pb1–x
Bi
x
S
y
NRs exhibited high values of the Seebeck coefficient (−181.31
μV/K at 450 K) and power factor (3.14 μW/cm·K2 at 650 K), and the electrical conductivity dramatically increased
from 0.91 to 14.88 S/cm with an increase in temperature.
Thermoelectric (TE) power generation offers a promising way to recover waste heat. The geometrical design of TE legs in modules is important to ensure sustainable power generation but cannot be easily achieved by traditional fabrication processes. Herein, we propose the design of cellular TE architectures for efficient and durable power generation, realized by the extrusion-based 3D printing process of Cu2Se TE materials. We designed the optimum aspect ratio of a cuboid TE leg to maximize the power output and extended this design to the mechanically stiff cellular architectures of hollow hexagonal column- and honeycomb-based TE legs. Moreover, we developed organic binder-free Cu2Se-based 3D-printing inks with desirable viscoelasticity, tailored with an additive of inorganic Se82- polyanion, fabricating the designed topologies. The computational simulation and experimental measurement demonstrated the superior power output and mechanical stiffness of the proposed cellular TE architectures to other designs, unveiling the importance of topological designs of TE legs toward higher power and longer durability.
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