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Metallic interface engineering is a promising strategy to stabilize Zn anode via promoting Zn2+ uniform deposition. However, strong interactions between the coating and Zn2+ and sluggish transport of Zn2+ lead to high anodic polarization. Here, we present a bio-inspired silk fibroin (SF) coating with amphoteric charges to construct an interface reversible electric field, which manipulates the transfer kinetics of Zn2+ and reduces anodic polarization. The alternating positively and negatively charged surface as a build-in driving force can expedite and homogenize Zn2+ flux via the interplay between the charged coating and adsorbed ions, endowing the Zn-SF anode with low polarization voltage and stable plating/stripping. Experimental analyses with theoretical calculations suggest that SF can facilitate the desolvation of [Zn(H2O)6]2+ and provide nucleation sites for uniform deposition. Consequently, the Zn-SF anode delivers a high-rate performance with low voltage polarization (83 mV at 20 mA cm−2) and excellent stability (1500 h at 1 mA cm−2; 500 h at 10 mA cm−2), realizing exceptional cumulative capacity of 2.5 Ah cm−2. The full cell coupled with ZnxV2O5·nH2O (ZnVO) cathode achieves specific energy of ~ 270.5/150.6 Wh kg−1 (at 0.5/10 A g−1) with ~ 99.8% Coulombic efficiency and retains ~ 80.3% (at 5.0 A g−1) after 3000 cycles.

In this paper, quaternary oxide semiconductor was applied as sensing material for the fabrication of gas sensors. One-step solvothermal method was utilized to synthesize the sensing material. Various characterization methods including XRD, XPS, SEM, HRTEM were employed to analyze the composition and structure of the sensing material. Composite composed of CuInW2O8 and CuWO4 was successfully prepared at last characterized by XRD result. The SEM result revealed the structure of the sensing material: nanoparticles assembled spindle-like nanostructure with ~200 nm long axis and ~60 nm short axis. Sensor based on the spindle-like nanostructures was systemically tested to acquire the information about the sensing properties. The sensor exhibited responses to acetone at the operating temperatures from 190 to 275 °C. The results showed that the sensor was more sensitive to acetone compared with other gases at the optimal operating temperature of 210 °C. The response of the sensor was also tested under the relative humidity from 25 RH% to 95 RH% at the operating temperature of 210 °C. The response variation was only 13.9%, demonstrating that the sensor possessed strong anti-humidity ability. It was worth noting that the sensor showed acceptable long-term stability compared with other acetone sensors. The gas sensing mechanism was also discussed here. This work might provide ideas for the development of novel sensitive materials for the application of gas sensors.

The sliver (Ag) modified zinc oxide (ZnO) nanorods were successfully obtained with a simplified and environmentally friendly solvothermal method. Materials characterization indicated that the metallic Ag was located on the outside of ZnO nanorods after annealing. In comparison with ZnO nanorods, Ag modified ZnO (Ag–ZnO) nanorods exhibited a considerably enhanced response to C2H2. The response of the 3 at% Ag–ZnO based sensor operating at 175 °C is 539 (Ra/Rg), which is the highest value among all the sensors in detecting 100 ppm C2H2. The Ag–ZnO based sensors exhibited fast response speed, lower operation temperature and higher selectivity.

Metal−organic frameworks (MOFs) with porous structures, high surface areas, diverse compositions, and functional linkers are promising materials and good carriers for building high-performance devices. In this work, uniform cobalt-doped ZnO nanoparticles (Co-doped ZnO NPs) derived from a MOF mold were synthesized, demonstrating the first example of synthesizing doped semiconductor metal oxide nanostructures using such strategy. The synthesis method produced Co-doped ZnO NPs that had a controllable doping mode, adjustable surface status, good dispensability, ferromagnetism and catalytic activity. The Co-doped ZnO NPs were evaluated as a sensing material for diabetes biomarker detection; the obtained sensors showed a high response to trace acetone (18.2 at 5 ppm), fast response/recovery times, a low detection limit (170 ppb), and long-term stability for 4 months. The enhanced sensing performance can be attributed to the increased number of active sites, additional impurity energy levels, and the catalytic ability of elemental Co. Moreover, the optimized sensor could distinguish between simulated diabetic breath and healthy human breath samples. The MOF-derived Co-doped ZnO NPs are a good candidate for the low-cost and noninvasive diagnosis of diabetes, and the proposed synthesis strategy can be extended to other types of extrinsically doped oxide materials.

The performance of perovskite solar cells (PSCs) can be improved by optimizing the perovskite film quality and electron transfer layers (ETLs). In this study, high-efficient PSCs with multi-cation hybrid electron transport layer (SnO

Abstract Environmentally friendly degradable sensors with both hazardous gases and pressure efficient sensing capabilities are highly desired for various promising applications, including environmental pollution monitoring/prevention, wisdom medical, wearable smart devices, and artificial intelligence. However, the transient gas and pressure sensors based on only identical sensing material that concurrently meets the above detection needs have not been reported. Here, we present transient all-MXene NO2 and pressure sensors employing three-dimensional porous crumpled MXene spheres prepared by ultrasonic spray pyrolysis technology as the sensing layer, accompanied with water-soluble polyvinyl alcohol substrates embedded with patterned MXene electrodes. The gas sensor achieves a ppb-level of highly selective NO2 sensing, with a response of up to 12.11% at 5 ppm NO2 and a detection range of 50 ppb–5 ppm, while the pressure sensor has an extremely wide linear pressure detection range of 0.14–22.22 kPa and fast response time of 34 ms. In parallel, all-MXene NO2 and pressure sensors can be rapidly degraded in medical H2O2 within 6 h. This work provides a new avenue toward environmental monitoring, human physiological signal monitoring, and recyclable transient electronics.

In this work, the mixed-potential-type gas sensor based on NASICON solid electrolyte and MMnO3 (M: Gd, Sm, La) sensing electrode (SE) was developed and fabricated aiming at the low-concentration triethylamine (TEA) detection. The research point of the fabricated sensors mainly concentrated on the effect of different A-site elements in MMnO3-SE (M: Gd, Sm, La) on TEA sensing characteristics. The result reveals that the highest response value (−217.5 mV) towards 50 ppm TEA was observed for the device utilizing SmMnO3-SE. The highest electrochemical catalytic activity of the fabricated sensors attached with SmMnO3-SE was further authenticated by the polarization curve measurement. Moreover, the response value displays a segmentally linear relationship with TEA concentrations and the logarithm of TEA concentrations, and the slopes are −49 mV/ppm and −105 mV/decade at the ranges of 0.05–0.5 ppm and 1–50 ppm TEA, respectively. The device could also produce an acceptable response value (−5.6 mV) towards 50 ppb TEA. Moreover, it also displays good repeatability and selectivity, along with steady response signals towards 5 ppm and 50 ppm TEA for 15 days and 1 ppm TEA at different humidity levels.

Here, the porous SnO2/Zn2SnO4 sensing electrode material prepared by facile hydrothermal method was applied to fabricate the mixed-potential-type gas sensor based on yttrium-stabilized zirconia (8 mol% Y2O3-doped ZrO2) solid electrolyte plane substrate for effectively detecting acetylene (C2H2) at 700 °C. In terms of the sensing characteristics of the C2H2 gas sensor, the response value toward 100 ppm C2H2 was -82.3 mV, and the detection limit of C2H2 was lowered to 500 ppb. The ΔV of the sensing device varied piecewise linearly with the logarithm of C2H2 concentration gradient range of 0.5–2 and 5–1000 ppm, with sensitivities of -12 and −56 mV/decade, respectively. In addition, the sensor exhibited good humidity stability, long stability, and selectivity to C2H2 at 700 °C. More interestingly, after high-temperature measurement (700 °C) for 20 consecutive days, the sensor continued to present good response transients, sensitivity, and reproducibility to C2H2. Furthermore, the sensing mechanism of the mixed-potential-type sensor was verified by measuring the polarization curves and complex impedance curves.

Organic light-emitting materials with thermally activated delayed fluorescence (TADF) are promising for promoting the efficiency of organic light-emitting diodes (OLEDs) without any precious metals...

Analyzing volatile organic compounds in exhaled breath is a noninvasive method that has potential for disease assessment. Herein, acetone sensors based on porous In2O3 flowers are synthesized through a facile solvothermal method. Structural characterizations demonstrate that the three-dimensional In2O3 flower-like structure comprises porous ultrathin two-dimensional nanosheets. The structural porosity results in a large specific surface area and fast gas diffusion, which can improve the gas sensing performance. The crystalline structure of the prepared hierarchical flower-like In2O3 is a mixed phase of rhombohedral and cubic phases according to the XRD patterns. The sensing properties of the cubic-rhombohedral In2O3 (bcc-rh-In2O3) are also investigated. Compared with commercial-In2O3-based sensor, the bcc-rh-In2O3 sensor exhibits 2.9 times higher response (Ra/Rg = 12) and shorter response time (ca. 2 s) toward 50 ppm acetone. The bcc-rh-In2O3 sensor has a low detection limit of 10 ppb in atmosphere and can easily distinguish acetone from ethanol. The extraordinary properties of the bcc-rh-In2O3 sensor are mainly attributed to the n-n heterojunction between rh-In2O3 and bcc-In2O3.

Nitrogen dioxide (NO2) sensing is important in terms of the agriculture development and healthcare monitoring. However, relatively poor recovery kinetics at a low temperature is still a problem for NO2 sensing and remains to be solved. In this work, we combine the excellent sensing properties and gas adsorption capacity of two- dimensional (2D) tin disulfide (SnS2) hexagonal nanoflakes with the beneficial electrical properties of graphene to build high-performance NO2 sensors by a simple and low-cost method. We found that the sensors based on the quasi-2D rGO-SnS2 hybrids exhibited exclusive selectivity towards NO2. The presence of rGO in hybrids decreased optimal working temperature effectively. Sensors based on 0.8% rGO-SnS2 (G-SS) show almost an order of magnitude increase in response (32) compared to pristine SnS2 (3.5). Especially, the response/recovery time is 50/48 s, respectively, demonstrating the favorable response/recovery kinetics of sensors. Such significant features can be attributed to the synergistic effect of the quasi-2D G-SS hybrid and the local heterojunctions in the interface between SnS2 and rGO.

In this work, we designed a multi-signal readout platform for sensitive monitoring carbamate pesticide based on gold nanoclusters-anchored MnO2 (AuNCs-MnO2) nanocomposite. The fluorescence of AuNCs was quenched by MnO2 via Forster resonance energy transfer effect. In the presence of acetylcholinesterase and choline oxidase, the substrate acetylcholine (ACh) is catalyzed to generate H2O2 that can specially induce the decomposition of MnO2, coupling with change of color and recovery of fluorescence. Carbamate pesticide as an inhibitor of acetylcholinesterase prevent the generation of H2O2, further block the breakage of MnO2, which caused the fluorescence switch. Such color and fluorescence respond can be utilized for highly sensitive carbamate pesticide identification and quantification. Under the optimum conditions, the dual-output assay possessed good sensitivity for rapid detection of carbaryl (model analyte) with a detection limit of 0.125 μg L−1. The fluorometric/colorimetric bimodal platform showed good stability and anti-interference ability comparing to that of others enzyme-based sensor.

Spinel-type oxides have attracted a broad interest in sensing materials research owing to their high catalytic activity and flexibly tunable chemical properties. Here, we report the synthesis of superfine porous NiFe2O4 microspheres by one-step solvothermal approach, in order to fabricate ultra-sensitive acetone sensors for real-time monitoring, relying on the high catalytic activity of NiFe2O4 and effective mass transfer property of porous microspheres structure. The porous NiFe2O4 sensors displayed high selectivity to acetone against other interfering gases, giving a high sensitivity (27.4), fast response time (2 s) towards 100 ppm acetone and low detection limit (200 ppb) at 250 °C. This paper proposed a general approach for fabricating highly sensitive gas sensor based on spinel-type oxides in monitoring volatile organic pollutants.

Due to the ultrathin structure, functional groups and excellent physical-chemical properties, Two-dimensional (2D) MXenes shows great potential for biomedical applications. Here, we prepared TiO2 inverse opal photonic crystals (IOPCs)/Ti3C2 quantum dots (QDs) composite film through the self-assembly method. Because of the widen absorption band of Ti3C2 QDs, TiO2 IOPCs/Ti3C2 composite film could have photocurrent effect from 280 to 900 nm, and the internal power conversion efficiency could reach to 26% at 350 nm. Owing to favourable energy levels, Ti3C2 QDs were formed the Type-II Heterojunction with TiO2, thus enabling directional transport charge for efficient charge separation. The Type-II Heterojunction photoelectrochemical (PEC) sensor consisting of TiO2/Ti3C2/Nafion electrode exhibited high stability, sensitivity, and selectivity for the detection of glutathione in buffered solution and cell extracts. Thus, the TiO2/Ti3C2/Nafion composite film provides a promising green electrode for sensitive PEC detection, which could realize some potential applications for disease early precaution and diagnose.

The development of room temperature NH3 sensors with flexible substrate can fulfill the future demands of high NH3 sensing performance under the premise of lower energy consumption and safety circumstance in wearable electronics field. The polyaniline and a serious of WO3 hollow spheres@ polyaniline hybrid were successfully synthesized via a combined route of simple hydrothermal method and in-situ chemical oxidative polymerization. The room temperature NH3 sensors were fabricated by assembling WO3 hollow spheres@ polyaniline hybrid on flexible polyethylene terephthalate (PET) films. The NH3 sensing properties of the fabricated devices demonstrated that the device utilizing 10 mol% WO3 hollow spheres@ polyaniline (PAWHs 10) hybrid exhibited the best sensing performance to 100 ppm NH3 (response value at 25) at 20 °C. Moreover, the PAWHs10 hybrid sensor also achieved excellent NH3 selectivity, ppb-level detection limit (1.67–500 ppb NH3), and good response/recovery rates (136 s/130 s) at 20 °C. The enhanced sensing performance of incorporation of polyaniline and WO3 hollow spheres was mainly attributed to the hollow structure of WO3 and the formation of p-n heterojunction between PANI and WO3 hollow spheres.

The preparation of size-controlled materials has shown remarkable potential with regard to their reinforced sensing performance. Herein, we report a facile solvothermal synthesis of dispersed WO3 nanoparticles with porous nanostructure caused by particle assembly. Various characterizations of the as-obtained samples were analyzed. Furthermore, the gas sensing properties of WO3 samples on volatile organic compounds were investigated. The results reveal that the gas sensors based on synthesized WO3 samples with suitable hexamethylenetetramine (HMT) amount and sintering treatment exhibit the highest response (132.0) towards 100 ppm toluene at the optimal working temperature of 225 °C with fast response/recovery time (2 s/6 s), which is attributed to the porous structure of the sensing film and the high resistance caused by well crystallization and grain boundary among the nanoparticles.

Herein, ZnO nanoflowers without any doping and modification were synthesized by hydrothermal method. The room temperature nitrogen dioxide sensor with high sensitivity, selectivity and long-term stability was prepared by combining ZnO nanoflowers with interdigital electrodes. The average diameter of the ZnO nanoflowers was about 0.9–1 μm. In addition, the gas sensing properties of the nitrogen dioxide gas sensors at room temperature were investigated. Compared with other ZnO sensors, the sensor based on the ZnO nanoflowers revealed outstanding sensing response to NO2, giving a response of 0.05–6 ppm. The sensor exhibited a lower detection limit of 0.05 ppm and had an ultra-high response to 1 ppm NO2 at room temperature. The response was only decreased by 16% of the initial value after 40 days of measurement. The Schottky barrier could be the key factor for the excellent NO2 sensing properties, which was formed between the Au electrodes and ZnO nanoflowers.

In this work, we developed a high-response mixed potential type yttria stabilized zirconia (YSZ) based planar gas sensing device utilizing CoTiO3 sensing electrode (SE) prepared via a facile sol-gel method to sensitively detect NO2 at an operating temperature of 650 °C. The present gas sensor coupled with 1200 ℃-sintered CoTiO3-SE exhibited high responses to NO2 in the concentration range of 500 ppb-200 ppm, as the value of the response was 130 mV to 100 ppm NO2. A linear relationship was observed between the ΔV of the sensor and the logarithmic scale of the NO2 concentration, which the sensitivity was 60 mV/decade. In addition, the sensor also displayed good reproducibility, the maximum response change of 5.4% and 16% in different coexisting gases and 98% high relative humidity, and response decrease of 6.9%–100 ppm NO2 after high temperature test for 20 days. Moreover, the sensing mechanism of sensor, which was based on mixed potential model, was confirmed using polarization curve measurements in air and different concentrations of NO2.