Recently, multivalent metal-ion batteries have attracted considerable interests on the merits of their natural abundance and multi-electron redox property. However, the development of Ca-ion battery ...is still in their preliminary stage because of the lack of suitable electrode material. The Ca-storage performance of the existing materials is still unsatisfactory with low capacity, poor cyclic stability, as well as sloping discharge profiles, which cannot provide stable energy output. In this work, transition metal oxide Sn-doped In
2
O
3
(ITO) has been explored as the aqueous Ca-ion battery anode, which could deliver a high discharge capacity of 71.2 mAh·g
−1
with an ultra-flat discharge voltage plateau. The Ca storage mechanism was revealed to be reversible conversion reaction based on
ex-situ
X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) characterizations. A flexible aqueous Ca-ion battery was subsequently assembled with zinc hexacyanoferrate (ZnHCF) cathode and ITO anode sandwiched by hydrogel electrolyte, which could deliver a high specific capacity of 75.3 mAh·g
−1
at 0.4 A·g
−1
with a flat output voltage plateau at around 0.8 V. The bendable and flexible Ca-ion battery with decent voltage output will pave the way for the energy storage devices towards practical applications in flexible and wearable electronics.
High-precision gas sensors operated at room temperature are attractive for various real-time gas monitoring applications, with advantages including low energy consumption, cost effectiveness and ...device miniaturization/flexibility. Studies on sensing materials, which play a key role in good gas sensing performance, are currently focused extensively on semiconducting metal oxide nanostructures (SMONs) used in the conventional resistance type gas sensors. This topical review highlights the designs and mechanisms of different SMONs with various patterns (
e.g.
nanoparticles, nanowires, nanosheets, nanorods, nanotubes, nanofilms,
etc.
) for gas sensors to detect various hazardous gases at room temperature. The key topics include (1) single phase SMONs including both n-type and p-type ones; (2) noble metal nanoparticle and metal ion modified SMONs; (3) composite oxides of SMONs; (4) composites of SMONs with carbon nanomaterials. Enhancement of the sensing performance of SMONs at room temperature can also be realized using a photo-activation effect such as ultraviolet light. SMON based mechanically flexible and wearable room temperature gas sensors are also discussed. Various mechanisms have been discussed for the enhanced sensing performance, which include redox reactions, heterojunction generation, formation of metal sulfides and the spillover effect. Finally, major challenges and prospects for the SMON based room temperature gas sensors are highlighted.
A comprehensive review on designs and mechanisms of semiconducting metal oxides with various nanostructures for room-temperature gas sensor applications.
Organic phase change materials (PCM) have been regarded as one of the most promising candidates for the application of energy storage and temperature control due to their advantages in latent heat. ...However, their intrinsically low thermal conductivity (λ) is the Achilles heel, and the most common solution is to utilize thermal conductive reinforcements to fabricate composite PCMs. The research focus remains how to promote the efficiency of thermal conductive reinforcements. Here, a CNT-Cu foam hybrid reinforcement was fabricated through a high temperature tube furnace process. Different from conventional carbon film coated metal foam, CNTs with the length comparable to the pore size were radially grown on the surface of Cu foam with Ni catalysts, which can not only reduce the low-λ regions inside the foam skeleton, but also connect every branches of the foam to improve the integrity of the whole reinforcement, and the thermal conductivity of the composite was promoted to 3.49 W·m−1·K−1 from 0.105 W·m−1·K−1 of paraffin. Moreover, this reinforcement exhibited abilities to compensate the loss of latent heat and suppress the supercooling of the composite, indicating their great prospects in the application of phase change energy storage and temperature control.
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•Carbon nanotube-Cu foam hybrid reinforcements were designed and fabricated.•Carbon nanotubes grown on skeleton can improve thermal conduction of inner pores.•Thermal conductivity of the composite was 3227% higher than that of the matrix.•The reinforcement can compensate the loss of latent heat in composites.
Surface acoustic wave (SAW) sensors have great advantages in real-time and in-situ gas detection due to the inherent advantages of passive and wireless operation. This inevitably requires the sensor ...to improve gas sensing performances at room temperature. The facet engineering of metal oxide (MOS) provided an effective way to obtain MOS gas-sensitive materials with superior performance by the facet-dependent properties. Here, we developed a novel strategy to prepare SnO2 quantum wires with different (110) facets ratio by adjusting the synthesis time. The as-prepared SnO2 quantum wires were integrated into SAW devices to optimize the performance of the gas sensor. When the synthesis time was 8 h, the response of the SAW gas sensor was enhanced with the frequency change of 17 kHz, the response and recovery times of 45 s and 96 s, respectively. Our experimental results revealed that the effect of mass loading was the responsible underlying mechanism for the superior NO2 gas sensing performances. In addition, the adsorption and charge transfer properties between the SnO2 surface and NO2 molecules were further discussed by QCM and resistance measurement, respectively. The calculation of density functional theory (DFT) also proves the adsorption energy of NO2 on the SnO2 (110) facet is larger than the (101) facet and (211) facet, indicating that the (110) facet is more beneficial to the adsorption of NO2 molecules. This indicated that the facet engineering of MOS by facet-dependent properties to enhance gas sensitivity may open new opportunities for the design of SAW sensor.
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•The SnO2 with different (110) facets ratio were prepared by adjusting the synthesis time.•The SnO2 with more exposed (110) facets exhibited high sensor response and low detection limit.•Chemiresistor sensor and QCM sensor were used to understand the SAW sensing mechanism for the NO2.
This work reports a high-performance Mn-doped ZnO multilayer structure Love mode surface acoustic wave (SAW) biosensor for the detection of blood sugar. The biosensor was functionalized via ...immobilizing glucose oxidase onto a pH-sensitive polymer which was attached on Mn-doped ZnO biosensor. The fabricated SAW glucose biosensor is highly sensitive, accurate and fast with good anti-interference. The sensitivity of the SAW glucose biosensor is 7.184MHz/mM and the accuracy is 6.96×10−3mM, which is sensitive and accurate enough for glucose monitoring. A good degree of reversibility and stability of the glucose sensor is also demonstrated, which keeps a constant differential frequency shift up to 32 days. Concerning the time response to human serum, the glucose sensor shows a value of 4.6±0.4min when increasing glucose concentrations and 7.1±0.6min when decreasing, which is less than 10min and reach the fast response requirement for medical applications. The Mn-doped ZnO Love mode SAW biosensor can be fully integrated with CMOS Si chips and developed as a portable, passive and wireless real time detection system for blood sugar monitoring in human serum.
•SAW biosensor was used to monitor blood sugar for the first time.•High performance SAW biosensor was fabricated on Mn-doped ZnO multilayer structure.•SAW glucose biosensor system was sensitive and accurate with good reversibility and stability.
This study has investigated the thermoelectric property of a layered metal dichalcogenide SnSe
2
, which is also non-toxic and earth abundant, especially with a similar composition of SnSe whose ...single crystals are recently revealed to possess high thermoelectricity. By investigating the electrical and thermal transport properties of Sn
1−
x
Ag
x
Se
2
(
x
= 0.00, 0.01, 0.03 and 0.05) in this work, it is revealed that the Ag-doped SnSe
2
has the potential as a good thermoelectric material used at mid-temperature, benefiting from its relatively low thermal conductivity below 1.0 Wm
−1
K
−1
and moderate power factor over 350 μWm
−1
K
−2
at 773 K. A ZT value of ~0.4 can be finally achieved for the composition of Sn
0.99
Ag
0.01
Se
2
at 773 K, which is an order of magnitude higher than the undoped ones and also larger than the reported metal dichalcogenides compounds of TiS
2
and WS
2
. The present work also reveals that Ag-doped sample shows much better thermal stability over 700 K compared with the undoped one whose measured temperature is only limited to 573 K, even with a few mole doping content of 1%.
In this work, solvent annealing process for CH₃NH₃PbI₃ thin film prepared by single source evaporation was reported. Characterized by the scanning electron microscope (SEM), X-ray diffractometer ...(XRD), energy dispersive spectroscope (EDS), ultraviolet-visible (UV) spectrophotometer, and the photoluminescence (PL) spectrometer, our method ensured higher quality film with crystallinity, composition, well-defined grain structure, and reproducibility. The optimized solar cell device based on the structure of ITO/PEDOT:PSS/CH₃NH₃PbI₃/PCBM/Ag achieved better performance in power conversion efficiency from 2.64% to 9.92%, providing an effective method to optimize the quality of perovskite film for solar cell application.
Herein, a highly sensitive, sandwich-type quartz crystal microbalance (QCM) immunosensor is proposed for the quantitative monitoring of alpha-fetoprotein (AFP), a representative tumor marker for ...hepatocellular carcinoma. A cuprous oxide @ molybdenum disulfide (Cu 2 O@MoS 2 ) nanohybrid was synthesized and combined with gold nanoparticles. The yield, a Cu 2 O@MoS 2 -Au nanocomposite, exhibited coral morphology with an increased surface area for loading more secondary antibodies (Ab 2 ), which amplified the mass loading on the QCM electrode's surface. The immunosensor's sensitivity was further enhanced by injecting the gold-staining solution for signal amplification. A self-assembled monolayer of primary antibody (Ab 1 ) was also fabricated on the QCM electrode's surface via mercaptoacetic acid immobilization in EDC and NHS. The immunosensor's limit of detection dropped to 35 pg/mL and 90 pg/mL with and without the gold enhancement, respectively. When used to detect AFP in human saliva and serum samples, the immunosensor displayed high selectivity and long-term stability, which indicates its potential for clinically monitoring of biomarkers.
A Ni/Cu/boron-doped diamond (Ni/Cu/BDD) complex electrode for non-enzymatic glucose electrochemical detection was prepared by a simple two-step heat treatment method. Scanning electron microscopy ...(SEM), Raman spectroscopy and electrochemical workstation were used to characterize the surface morphology, composition and electrochemical properties of the electrode, respectively. The results showed that Ni reacted with BDD under high temperature catalytic conditions forming a porous structure, and stabilized Cu on the surface of BDD due to the superior wettability between Cu and Ni. Compared to Ni/BDD and Cu/BDD electrodes, Ni/Cu/BDD electrode exhibited enhanced catalytic activity in glucose detection, such as an extremely wide detection range (0.022–18.3mM), high sensitivity (1007.688 μAmM−1cm−2, which was 1.28 times higher than that of the Ni/BDD electrode), great selectivity and excellent long-term stability (93.3% after one month).
•The Ni/Cu/BDD electrode exhibits excellent long-term stability because nickel particles are embedded into the diamond forming a porous structure, which avoids the peel-off of Ni/Cu NPs during the detection.•The Ni/Cu/BDD exhibits enhanced catalytic activity compared with Ni/BDD owing to the addition of Cu nanoparticles.•The synergistic effect of nickel nanoparticles, copper nanoparticles and BDD films is well discussed for the first time.
We provided a new method to improve the efficiency of Sb₂S₃ thin film solar cells. The TiO₂ electron transport layers were doped by lithium to improve their charge extraction properties for the ...thermal-evaporated Sb₂S₃ solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO₂ films. Compared with the undoped TiO₂, Li-doped mesoporous TiO₂ dramatically improved the photo-voltaic performance of the thermal-evaporated Sb₂S₃ thin film solar cells, with the average power conversion efficiency (
) increasing from 1.79% to 4.03%, as well as the improved open-voltage (
), short-circuit current (
) and fill factors. The best device based on Li-doped TiO₂ achieved a power conversion efficiency up to 4.42% as well as a
of 0.645 V, which are the highest values among the reported thermal-evaporated Sb₂S₃ solar cells. This study showed that Li-doping on TiO₂ can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb₂S₃-based solar cells.
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