Density functional theory (DFT) predicts superior lithium-ion diffusion via the (101) plane of NaNbO3. Experimental results confirm that despite a reduction in surface area, 6 mu m NaNbO3 cubes with more (101) plane exposure exhibit enhanced Li+ storage, underscoring the significance of crystal facet engineering.

Photocatalytic water splitting for hydrogen production is a promising solution to address the global energy crisis, but its development is hampered by low catalyst efficiency. This study introduces an approach to improve the photocatalytic performance of BaTiO3 (BTO) by engineering its crystalline phase through simple thermal annealing. The optimized BaTiO3 composition, with a 43 % cubic (C-BTO) and 57 % tetragonal (T-BTO) phase ratio, achieved a remarkable hydrogen evolution rate of 2245.1 mu mol g-1 h-1 with long-term stability over 25 h, representing a ten-fold enhancement over pristine BTO. Experimental results indicate that this crystal phase engineering enhances photogenerated electron-hole separation and migration, significantly improving photocatalytic efficiency. This work offers an effective strategy for enhancing single photocatalyst performance, paving the way for more efficient hydrogen production.

Detecting H2 at low concentrations is important due to it being a major safety concern in practical applications. However, semiconductor chemiresistive gas sensors always suffer from high operating temperatures and power consumption, as well as a limited concentration detection range, which restricts their widespread use. Herein, we developed a 3D nanostructured gas sensor employing a Pd-nanocluster-decorated SnO2 nanotube array as the sensing layer. The sensor showed sensitive and selective properties for detecting low concentrations of H2 at room temperature, with a low limit of detection of 1.6 ppb. It also showed good long-term stability, as long as 100 days. Moreover, systematical characterizations were performed in conjunction with density functional theory (DFT) calculations to determine the ability of Pd/SnO2 junctions to improve the gas-sensing properties. The engineering of the nano-Schottky junction allows us to expand the library for designing low-power-consumption H2 sensors for widespread applications.

It is greatly crucial to develop low-cost energy storage candidates with high safety and stability to replace alkali metal systems for a sustainable future. Recently, aqueous zinc-ion batteries (ZIBs) have received tremendous interest owing to their low cost, high safety, wide oxidation states, and sophisticated fabrication process. Nanostructured manganese (Mn)-based oxides in different polymorphs are the potential cathode materials for the widespread application of ZIBs. However, Mn-based oxide materials suffer from several drawbacks, such as low electronic/ionic conductivity and poor cycling performance. To overcome these issues, various structural modification strategies have been adopted to enhance their electrochemical activity, including phase/defect engineering, doping with foreign atoms (e. g., metal and/or nonmetal atoms), and coupling with carbon materials or conducting polymers. Herein, this review targets to summarize the advantages and disadvantages of the above-mentioned strategies to improve the electrochemical performance of the cathodic part of ZIBs. The challenges and suggestions for the development of manganese oxides for ZIBs are put forward.

Electrochemical biosensors have emerged as one of the promising tools for tracking human body physiological dynamics via non-invasive perspiration analysis. However, it remains a key challenge to integrate multiplexed sensors in a highly controllable and reproducible manner to achieve long-term reliable biosensing, especially on flexible platforms. Herein, a fully inkjet printed and integrated multiplexed biosensing patch with remarkably high stability and sensitivity is reported for the first time. These desirable characteristics are enabled by the unique interpenetrating interface design and precise control over active materials mass loading, owing to the optimized ink formulations and droplet-assisted printing processes. The sensors deliver sensitivities of 313.28 µA mm-1 cm-2 for glucose and 0.87 µA mm-1 cm-2 for alcohol sensing with minimal drift over 30 h, which are among the best in the literature. The integrated patch can be used for reliable and wireless diet monitoring or medical intervention via epidermal analysis and would inspire the advances of wearable devices for intelligent healthcare applications.

WO3-based photocatalysts have garnered popularity due to their low cost and high stability. However, the strong photogenerated electron-hole recombination limits their practical applicability. Herein, we developed an innovative heterostructure that integrates silver nanoparticles (Ag NPs) into carbon-encapsulated WO3 (C-WO3) through a combination of solvothermal synthesis and photoreduction methods. Under visible light irradiation, the Ag/C-WO3 photocatalyst demonstrated significant photocatalytic activity for rhodamine B (RhB) degradation, and the fine-tuned Ag/C-WO3 photocatalyst possesses excellent RhB degradation performance, achieving a removal rate of 98.2 % with excellent photostability. The photocatalytic process follows first-order kinetics, with adsorbent diffusion identified as the rate-limiting step. The optimized Ag/C-WO3 had an apparent rate constant of 0.039 min(-1), 9.75 times higher than that of the unmodified C-WO3 (0.004 min(-1)). The enhanced photocatalytic activity is primarily owing to the surface plasmon resonance effect of Ag NP, which increases the absorption of visible light and boosts electron generation. Additionally, the carbon layer that encapsulates WO3 serves as a bridge for electron transfer from Ag to WO3, thereby accelerating the separation of photogenerated electron-hole pairs and elevating the overall photocatalytic degradation efficiency. The Ag NP-decorated C-WO3 with superior degradation properties is expected to be a potential candidate in practical and industrial applications.

Human olfactory sensors have a large variety of receptor cells that generate signature responses to various gaseous molecules. Ideally, artificial olfactory sensors should have arrays of diverse sensors. However, it is challenging to monolithically integrate large-scale arrays of different high-performance gas sensors. Here we report biomimetic olfactory chips that integrate nanotube sensor arrays on nanoporous substrates with up to 10,000 individually addressable sensors per chip. The range of sensors is achieved using an engineered material composition gradient. Supported by artificial intelligence, the chips offer a high sensitivity to various gases with excellent distinguishability for mixed gases and 24 distinct odours. We also show that the olfactory chips can be combined with vision sensors on a robot dog to create a system that can identify an object in a blind box. A biomimetic olfactory system that integrates nanotube sensor arrays with up to 10,000 individually addressable sensors per chip can offer high sensitivity to various gases with excellent distinguishability for mixed gases and 24 distinct odours.

Inadequate limit of detection at room temperature and unsatisfactory selectivity remain challenge for wide applications of the chemiresistive gas sensors. Nanostructured gas sensors ensure the desirable activation energy for the gas adsorption and chemical reactions, favorable for room-temperature parts-per-billion (ppb) level gas detection. In this work, we demonstrated a single-chip integrated gas sensor array (4 x4 pixels) based on kinds of metal (Pt, Pd, Au, Ag) decorated 3D SnO2 nanotubes for ultrasensitive room-temperature gas-sensing. The nanostructured sensor array has a high surface area-to-volume ratio, enabling room temperature sensing with high detection response toward H2 (minimum 5 ppm), formaldehyde (minimum 50 ppb), toluene (minimum 50 ppb) and NO2 (minimum 100 ppb) with the detection accuracy within 5% range, respectively. In addition, the effect of metals decoration on the gas identification features were systematically conducted, and these specific response features can be mainly attributed to metal activation capability toward the gases, which enables demonstrating differentiable response patterns for the target gases identification employing a pattern recognition algorithm. These results demonstrate that the proposed strategy helps to provide an excellent route for the future low-power-consumption smart sensing devices design and fabrication.

The limited active sites and faster photogenerated electron-hole pair recombination rate of g-C3N4 restrict its application in photocatalytic H2 production. Constructing heterojunctions has been shown to improve the spatial (directional) separation of photogenerated electrons and holes. However, due to interface mismatch in traditional heterojunction structures and a lack of precise electron transport channels, the photocatalytic efficiency is limited. Here, we developed a two-step calcination approach to create an Fe2N/g-C3N4 heterojunction linked by Fe-O bonds (named as Fe-OCN). The newly formed Fe-O bonds within the heterojunction can act as atomic-level interface electron transfer channels, directly transferring the photogenerated electrons of g-C3N4 to the reactive center Fe2N, significantly improving the charge transfer rate and utilization, thus promoting visible-light-driven photocatalytic H2 production. The optimal Fe-OCN achieved a H2 production rate of 5986.29 μmol g-1 h-1 under visible light, 13.44 times higher than that of the OCN due to efficient charge separation and transfer capabilities. This work provides a constructive reference for the design and synthesis of organic-inorganic heterojunction with chemically bonded interfaces, establishing quick electron transfer channels, and achieving targeted electron transfer.

The analysis of exhaled human breath has great significance for early noninvasive diagnosis. However, highly sensitive and selective detection against part-per-billion (ppb) biomarkers in exhaled human breath (RH = 80%) at room temperature remains a challenge. SnO2 quantum wires (QWs) consisting of a few hundreds to thousands of atoms are demonstrated to be promising for low-power consumption gas sensors to achieve an on-chip electronic nose. Here, we propose a low-temperature doping strategy in realizing the synthesis of the transition metal (Mn, Cr, V)-doped SnO2 QWs. The doped SnO2 QWs with sub-4 nm diameters as chemiresistive gas sensors enable us to improve the adsorption activities, achieving enhanced room-temperature sensing properties toward the trace biomarkers (e.g., acetone, formaldehyde, and H2S) with the state-of-the-art limit of detection of 2.6, 1.5, and 1.3 ppb, respectively. These transition metal-doped SnO2 QWs are then integrated as a sensor array, enabling gas identification at different relative humidities by using machine learning algorithms. Moreover, systematical characterizations combined with density functional theory (DFT) calculations are conducted to figure out the effect of doping on SnO2 QW properties for the sensitive and selective ppb-level gas detection. The engineering of transition metal-doped SnO2 QWs helps us to extend the library for the design of low-power consumption gas sensors in more broad applications.

Real-time monitoring of health threatening gases for chemical safety and human health protection requires detection and discrimination of trace gases with proper gas sensors. In many applications, costly, bulky, and power-hungry devices, normally employing optical gas sensors and electrochemical gas sensors, are used for this purpose. Using a single miniature low-power semiconductor gas sensor to achieve this goal is hardly possible, mostly due to its selectivity issue. Herein, we report a dual-mode microheater integrated nanotube array gas sensor (MINA sensor). The MINA sensor can detect hydrogen, acetone, toluene, and formaldehyde with the lowest measured limits of detection (LODs) as 40 parts-per-trillion (ppt) and the theoretical LODs of ∼7 ppt, under the continuous heating (CH) mode, owing to the nanotubular architecture with large sensing area and excellent surface catalytic activity. Intriguingly, unlike the conventional electronic noses that use arrays of gas sensors for gas discrimination, we discovered that when driven by the pulse heating (PH) mode, a single MINA sensor possesses discrimination capability of multiple gases through a transient feature extraction method. These above features of our MINA sensors make them highly attractive for distributed low-power sensor networks and battery-powered mobile sensing systems for chemical/environmental safety and healthcare applications.

Doping is fundamental to controlling the properties of bulk semiconductors. Although the antimony (Sb V )‐doping strategy is widely employed in the design of practical tin oxide (SnO 2 ) semiconductor gas sensors for higher signal‐to‐noise ratio, challenges remain to dope semiconductor nanocrystals since the diffusion of impurity atoms may be far from realized at the synthesis temperatures used. Herein, a metastable Sb‐doping strategy is proposed to overcome the serious receptor‐versus‐transducer mismatch in SnO 2 quantum wires (QWs). The solvothermal synthesis of colloidal Sb III ‐doped SnO 2 QWs has been conducted at 180 °C, whereby the antimony amount is varied to optimize the structural and morphological properties for higher surface activity and electrical conductivity. A unique n‐type doping mechanism arising from the stable presence of Sb III on SnO 2 (101) facets via Sn II ‐O‐Sb III is demonstrated. Further, the use of sensitive (down to 4 ppb, the lowest detection limit ever reported), fast (response and recovery time of 43 s and 96 s toward 10 ppm of H 2 S) gas sensors for H 2 S detection at near room temperature (40 °C) is showcased. The metastable Sb‐doping strategy may pave the way to ultrasensitive gas sensor possessing low power consumption and excellent integration compatibility to satisfy the increasing demand for ubiquitous and reliable gas detection.

Semiconductor chemiresistive gas sensors play critical roles in a smart and sustainable city where a safe and healthy environment is the foundation. However, the poor limits of detection and selectivity are the two bottleneck issues limiting their broad applications. Herein, a unique sensor design with a 3D tin oxide (SnO2 ) nanotube array as the sensing layer and platinum (Pt) nanocluster decoration as the catalytic layer, is demonstrated. The Pt/SnO2 sensor significantly enhances the sensitivity and selectivity of NO2 detection by strengthening the adsorption energy and lowering the activation energy toward NO2 . It not only leads to ultrahigh sensitivity to NO2 with a record limit of detection of 107 parts per trillion, but also enables selective NO2 sensing while suppressing the responses to interfering gases. Furthermore, a wireless sensor system integrated with sensors, a microcontroller, and a Bluetooth unit is developed for the practical indoor and on-road NO2 detection applications. The rational design of the sensors and their successful demonstration pave the way for future real-time gas monitoring in smart home and smart city applications.

Two-dimensional carbon nitride (2D-C3N4) nanosheets are promising materials in photocatalytic water splitting, but still suffer from easy agglomeration and fast photogenerated electron-hole pairs recombination. To tackle this issue, herein, a hierarchical Nb2O5/2D-C3N4 heterostructure is precisely constructed and the built-in electric field between Nb2O5 and 2D-C3N4 can provide the driving force to separate/transfer the charge carriers efficiently. Moreover, the strongly Lewis acidic Nb2O5 can adsorb TEOA molecules on its surface at locally high concentrations to facilitate the oxidation reaction kinetics under irradiation, resulting in efficient photogenerated electrons-holes separation and exceptional photocatalytic hydrogen evolution. As expected, the champion Nb2O5/2D-C3N4 heterostructure achieves an exceptional H-2 evolution rate of 31.6 mmol g(-1) h(-1), which is 213.6 times and 4.3 times higher than that of pristine Nb2O5 and 2D-C3N4, respectively. Moreover, the champion heterostructure possesses a high apparent quantum efficiency (AQE) of 45.08% at lambda = 405 nm and superior cycling stability. Furthermore, a possible photocatalytic mechanism of the energy band alignment at the hetero-interface is proposed based on the systematical characterizations accompanied by density functional theory (DFT) calculations. This work paves the way for the precise construction of a high-quality heterostructured photocatalyst with efficient charge separation to boost hydrogen production. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Sub-3 nm metal-doped SnO 2 quantum wires (QWs) were synthesized using a solution process. The sensor film prepared using W-doped SnO 2 QWs at room temperature achieves enhanced low-temperature H 2 S-sensing with a record limit of detection of 0.48 ppb.

Graphitic carbon nitride (g-C3N4y) is a promising material for photocatalytic water splitting but suffers from the self-agglomeration and fast recombination of photogenerated electron-hole pairs. Tin oxide (SnO2) has a high electron extraction ability and can play a key role in the charge separation and transfer dynamics of composites. Herein, we report a 0D/2D heterostructure of carbon-encapsulated SnO2 quantum dots (SnO2@C QDs) anchored on g-C3N4 nanosheets (SnO2@C/CN). The construction of interface between SnO2@C and g-C3N4 dramatically increases the surface area and the number of active sites for photocatalytic hydrogen evolution reaction (HER) and provides a driving force for efficient charge separation/transfer kinetics. The carbon layer encapsulating SnO2 QDs acts as a bridge that facilitates electron transfer from g-C3N4 to SnO2 QDs. The champion SnO2@C/CN achieves an exceptional HER rate of 2,544.3 mu mol g(-1) h(-1) (with 3 wt% Pt) with an apparent quantum efficiency of 9.63 % (lambda = 420 nm) and excellent photostability. A photoactivity enhancement mechanism is proposed based on the interfacial energy band alignment. This work provides insights into the designing of heterostructured photocatalysts of enhanced charge separation via interface engineering.

The accelerated evolution of communication platforms including Internet of Things (IoT) and the fifth generation (5G) wireless communication network makes it possible to build intelligent gas sensor networks for real-time monitoring chemical safety and personal health. However, this application scenario requires a challenging combination of characteristics of gas sensors including small formfactor, low cost, ultralow power consumption, superior sensitivity, and high intelligence. Herein, self-powered integrated nanostructured-gas-sensor (SINGOR) systems and a wirelessly connected SINGOR network are demonstrated here. The room-temperature operated SINGOR system can be self-driven by indoor light with a Si solar cell, and it features ultrahigh sensitivity to H-2, formaldehyde, toluene, and acetone with the record low limits of detection (LOD) of 10, 2, 1, and 1 ppb, respectively. Each SINGOR consisting of an array of nanostructured sensors has the capability of gas pattern recognition and classification. Furthermore, multiple SINGOR systems are wirelessly connected as a sensor network, which has successfully demonstrated flammable gas leakage detection and alarm function. They can also achieve gas leakage localization with satisfactory precision when deployed in one single room. These successes promote the development of using nanostructured-gas-sensor network for wide range applications including smart home/building and future smart city.

In this contribution, polythiophene (PTh)/Bi4O5I2 nanocomposites are successfully synthesized through a facile route at room temperature, and evaluated as photocatalysts for the photocatalytic degradation of bisphenol a (BPA). It was discovered that the introduction of polythiophene (PTh) obviously enhanced the separation efficiency of photocharge carriers, thus promote the photocatalytic ability of Bi4O5I2. Among the as-prepared PTh/Bi4O5I2 nanocomposites, 0.5% PTh/Bi4O5I2 exhibited the optimal photocatalytic activity, the BPA degradation rate was 99.2% in 30 min. The reaction rate is about 3.7 times as high as that of pure Bi4O5I2. Moreover, the degradation products of BPA were analyzed by high performance liquid chromatography. The good stability of the composite was discovered by cyclic experiments. Finally, a possible photocatalytic mechanism was proposed. (C) 2020 Elsevier B.V. All rights reserved.

For the first time, herein this work, we have developed an effective and adaptable method to introduce defects onto the polymeric carbon nitride by simply grinding urea with urea nitrate which resulting new carbon nitride composite (UNU-C3N4) and melamine with urea nitrate which resulting new carbon nitride composite (UNM-C3N4). The UNU-C3N4 reveals high performance towards photocatalytic hydrogen production and as well as photocatalytic removal of contaminants. The results confirm that the defects enhanced the specific surface area, and improved performance of adsorbed oxygen which beneficial to generate more active radicals and more conducive sties to improve d the overall photocatalytic performance. The high N, H, and O content-enhanced electron polarization effects, by introducing the additional N, H, and O atoms into the g-C3N4 matrix, which will increase the charge transfer rate and charge separation efficiency. At the same time, the results of ESR also expression that the new type of as-prepared carbon nitride samples exhibit abundant of hydrogen radical (H) formation, which is also assist to improve the photocatalytic hydrogen production performance. As expected, the H2 evolution rate of UNU-C3N4(or UNM-C3N4) underneath simulated solar light irradiation is 9.93 times (13.76 times) than that of U-C3N4 (urea as raw material) (or M-C3N4 (melamine as raw material)). The high hydrogen evolution rates of UNU-C3N4 and UNM-C3N4 are 830.94 and 556.79 μmol g-1  h-1 under the visible-light irradiation, respectively. Meanwhile, the synthesized UNU-C3N4 and UNM-C3N4 material are demonstrated an efficient ability to degrade pollutants. In general, this work provides a viable way to introduce defects and hydrogen bands into the structure of carbon nitride.