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The development of a highly flexible, ultra-selective, and stable gas sensor is crucial in wearable electronic devices. Herein, carbon nanofibers (CNFs)/NiCo2O4 with different nanostructures were prepared and assembled as gas sensors for methanol detection. The CNFs/NiCo2O4 prepared by potassium permanganate treatment showed the highest gas sensitivity (0.1–100 ppm) and a good linear response. Meanwhile, the CNF/NiCo2O4 composite membrane sensors were tested after bending at different angles of 30°, 60°, and 90°. The response efficiencies could be maintained at 90.8%, 88.7%, and 87.1%, respectively, after 50 cycles, indicating that the sensors had good stability and flexibility. This approach provides a strategy for the controllable design and synthesis of homogeneous hierarchical CNF/transition metal oxide (TMO) composites for flexible gas sensor. [ABSTRACT FROM AUTHOR]

A novel self‐healing poly(vinyl alcohol) (PVA)‐based hydrogel is developed by cross‐linking PVA chains through multi dynamic covalent bonds by use of a small cross‐linker composed by 4‐formylphenylboric acid (FPBA) and lysine (Lys). The dynamic borate‐imine‐imine‐borate bond structure between PVA chains endows the hydrogel excellent stretchability and ultra‐fast self‐healing ability without external stimulation. The self‐healing efficiency can attain 94% and the elongation at break can reach up to near 1000% after only 3 min healing. Moreover, the self‐healing of the hydrogel through the contact of two faces from both the same cut position and different cut positions has similar excellent efficiency. The hydrogel with the unusual self‐healing performance and stretchability is used as an ideal material in strain sensors monitoring human movement and tiny vibrations caused by human voice. Interestingly, the sensor can continue to function normally after self‐healing for only ≈3 s. It is expected that this simple strategy of fabricating self‐healing hydrogels with multi dynamic bonds will provide new opportunities in the design and preparation of PVA‐based hydrogels to expand their potential applications in sensors and other various fields. [ABSTRACT FROM AUTHOR]

To assemble small nanoparticles into a hollow polyhedron superstructure as a sensing material is a promising approach to improve the performance of metal-oxide–semiconductor gas sensors. In this study, ZnCo2O4 hollow polyhedrons (ZnCo2O4 HP) assembled by small nanoparticle-building blocks were prepared by simple one-step calcination of ZIF-67/ZIF-8 composites. Benefiting from rich active sites and abundant oxygen defects, ZnCo2O4 HP exhibited high response (∼0.7 ppm−1) and low limits of detection (1 ppm) to ethanol vapor at a temperature of 200 °C compared with other similar ethanol sensors. The sensing mechanism was investigated to identify the underlying surface chemical processes in different atmospheres by operando near ambient pressure X-ray photoelectron spectroscopy (NAPXPS). The obtained spectral data indicated that oxygen adsorbed on the surface as active oxygen could react with ethanol molecules, which were decomposed into carboxylates. The present study provides strategies for the rational design of AB2O4 materials, as well as an advanced method for the study of its sensing mechanism. [ABSTRACT FROM AUTHOR]

Objectives: To explore the perceptions of patients undergoing percutaneous coronary intervention (PCI) regarding their pre‐operative health education. Methods: A qualitative study using semi‐structured, in‐depth interviews was conducted in one cardiology unit in China from July 2019 to December 2019. Purposeful sampling of 17 patients undergoing PCI was interviewed about their perceptions of pre‐operative health education. Thematic analysis of the transcribed data was then used to identify the themes. Results: Four themes emerged from the data:(a) triple roles of pre‐operative education with the categories of relief (reliving fear); burden (leading to stress); and meaningless (changing nothing); (b) family member involvement with the categories of shared responsibility and family members' duty; (c) facilitators in the process of pre‐operative health education with the categories of emotional support, plain language and individualized pre‐operative education; (d) inhibitors in the process of pre‐operative health education with the categories of contradiction and threatening words. Conclusions: Pre‐operative health education for patients undergoing PCI should be aligned with the individual patients' information‐seeking styles and personal differences, emphasizing individualized patient education. Traditional Chinese philosophy should be considered in the practice of pre‐operative education for patients undergoing PCI, which emphasizes family member involvement; at the same time, patient empowerment and self‐care should also be stressed. In addition, emotional support and plain language from health professionals are important in pre‐operative health education for patients undergoing PCI; contradiction should be avoided, and threatening words should be used with caution and with consideration for cultural variations during pre‐operative education for patients undergoing PCI. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) aerogel with special porous structure can combine the advantages of its high adsorbability with excellent mechanical properties to show excellent performance in the capture of particulate matter smaller than 2.5 μm (PM2.5) and in the recycling of the aerogel. However, the fabrication of the aerogel with durable ordered large through-pores is challenging due to lack of an effective strategy to control the porous structure from the randomly arranged GO sheets. Herein, a facile fabrication strategy towards the stable honeycomb-like-structured GO aerogel, comprising large-sized GO sheets (LGO), via freeze casting with the help of the electrostatic field effect of tourmaline is reported. The added modified tourmaline nanoparticles (mTNPs) effectively reduce the repulsion between GO sheets and highly promote the ordered stacking of LGO sheets to form honeycomb-like-structured aerogel possessing stable large through-pores. Benefiting from its special porous structure, this hybrid aerogel exhibits superior adsorption for PM2.5 and superior recycling performance. When mTNPs loading is 5 wt%, the PM2.5 filtration efficiency of the aerogel is up to 95.1% in the first adsorption cycle, and more importantly, the aerogel can be used repeatedly and retain the high filtration efficiency after simple recycling. [ABSTRACT FROM AUTHOR]

Highly sensitive and fast detection of volatile organic compounds (VOCs) in industrial and living environments is an urgent need. The combination of distinctive structure and noble metal modification is an important strategy to achieve high-performance gas sensing materials. In addition, it is urgent to clarify the chemical state and function of noble metals on the surface of the sensing material during the actual sensing process. In this work, Pd modified Co 3 O 4 hollow polyhedral (Pd/Co 3 O 4 HP) is developed through one-step pyrolysis of a Pd doped MOF precursor. At an operating temperature of 150 °C, the Pd/Co 3 O 4 HP gas sensor can achieve 1.6 times higher sensitivity than that of Co 3 O 4 HP along with fast response (12 s) and recovery speed (25 s) for 100 ppm ethanol vapor. Near-ambient pressure X-ray photoelectron spectroscopy (NAPXPS) was used to monitor the dynamic changes in the surface state of Pd/Co 3 O 4 HP. The NAPXPS results reveal that the oxidation and reduction of Pd in the ethanol sensing process are attributed to a spillover effect of oxygen and ethanol, respectively. This work opens up an effective approach to investigate spillover effects in a sensing mechanism of noble metal modified oxide semiconductor sensors., Competing Interests: All authors declare that there are no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

Two-dimensional (2D) nonlayered nanomaterials have attracted extensive attention for electronic and optoelectronic applications recently because of their distinct properties. In this work, we first employed a facile one-step method to synthesize 2D nonlayered cadmium sulfide selenide (CdS x Se 1- x , x = 0.33) nanosheets with a highly crystalline structure and then we introduced a generic spin-coating approach to fabricate hybrid nanomaterials composed of PbS quantum dots (QDs) and 2D CdS x Se 1- x nanosheets and demonstrated their potential for high-performance broadband photodetectors. Compared with pure 2D CdS x Se 1- x nanosheet photodetectors, the photoelectric performance of the PbS/CdS x Se 1- x hybrid nanostructure is enhanced by 3 orders of magnitude under near-infrared (NIR) light illumination and maintains its performance in the visible (Vis) range. The photodetector exhibits a broadband response range from Vis to NIR with an ultrahigh light-to-dark current ratio (3.45 × 10 6 ), a high spectral responsivity (1.45 × 10 3 A/W), and high detectivity (1.05 × 10 15 Jones). The proposed QDs/2D nonlayered hybrid nanostructure-based photodetector paves a promising way for next-generation high-performance broadband optoelectronic devices.