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[Display omitted] • Hydrophobic eutectogel is facilely produced through the polymerization of hydrophobic monomers in a hydrophobic DES. • The hydrophobic eutectogel shows outstanding water resistance (water contact angle over 110°) and extraordinary durability (over 1000 testing cycles) underwater. • Hydrophobic eutectogel can be utilized as strain and pressure sensors underwater. • Hydrophobic eutectogel sensors can transmit information through Morse code, performing as a underwater communicator. Eutectogels derived from deep eutectic solvents (DESs) exhibit great potential for the fabrication of flexible sensors. However, the hygroscopicity of eutectogels hinders their applications in underwater sensing. In this work, a hydrophobic eutectogel with exceptional long-term underwater stability is produced through one-step polymerization of lauryl methacrylate and glycidyl methacrylate in a hydrophobic DES. The hydrophobic gel network and hydrophobic DES fulfill the eutectogel with outstanding water resistance (water contact angle > 110°) and excellent mechanical properties in an aqueous environment, thus leading to extraordinary durability (over 1000 testing cycles). Additionally, based on this eutectogel, underwater strain and pressure sensors with high sensitivity, rapid responsiveness, and superior durability were fabricated for accurate real-time monitoring of human activity. Furthermore, it has been demonstrated that the eutectogel sensor can transmit information through Morse code, performing as a wearable underwater communicator. This research provides an exemplary way for a demonstration method of hydrophobic eutectogel for durable underwater applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Excessive CO 2 emissions have contributed to global environmental issues, driving the development of CO 2 capture adsorbents. Among various candidates, metal–organic frameworks (MOFs) are considered the most promising due to their unique microporous structure. Herein, a series of partially interpenetrated MOFs named UPC-XX were built to investigate the continuous enhancement in CO 2 capture performance via synergistic effects from functional group, pore size, and steric-hindrance using theoretical calculations. It's showed that the introduction of functional groups improved the structure polarity and created more adsorption sites, thus, enhanced CO 2 capture capacity. The pore size modification augments the exposure of adsorption sites to mitigate the negative impact of pore space and surface area reduction caused by the introduction of functional groups, thereby further increasing the CO 2 capture capacity. The steric-hindrance effect optimized the adsorption sites distribution, which hasn't been considered in the previous two regulation strategies, thus, further increased the CO 2 capture capacity. The results underscore UPC-MOFs as outstanding adsorbent materials, among the UPC-MOFs, UPC-OSO 3 -steric exhibited the highest CO 2 capture capacity of 12.69 mmol/g with selectivities of 1142.41 (CO 2 over N 2) and 507.42 (CO 2 over CH 4) at 1.0 bar, 298 K. And the synergistic effect mechanisms of functional group, structure size, and steric hindrance were elucidated through theoretical calculations analyzing pore characteristics, gas distribution, isosteric heat, and van der Waals/Coulomb interactions. [ABSTRACT FROM AUTHOR]

• Fluorescent carbon polymer materials are prepared by mixing H 2 SO 4 and DETA at room temperature. • The samples possess unique hollow nanospheres structure with strong fluorescence property. • Such fluorescent carbon polymer hollow spheres are used as peroxidase mimics for H 2 O 2 detection. Fluorescent carbon polymer nanomaterials driven by their important various applications are promising, however, their scalable usages are still hindered by the lack of facile and effective synthesis approaches. Herein, a rapid and facile approach is demonstrated for the preparation of fluorescent carbon polymer hollow spheres (CPHSs), which were synthesized by directly mixing concentrated sulfuric acid (H 2 SO 4) and diethylenetriamine (DETA) at room temperature. Notably, both the solid powders and aqueous dispersion of CPHSs possess the fluorescence properties, similar with the reported carbon polymer dots. The formation of CPHSs could be attributed to the polymerization of DETA in the presence of H 2 SO 4. The present strategy is universal and fluorescent nanomaterials could also be obtained by using hexamethylenetetramine or polyethylenepolayamine as precursors with the aid of concentrated H 2 SO 4. Most importantly, the CPHSs possess peroxidase-like activity and can catalyze oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to its one-electron oxidation product, providing a new method for colorimetric detection of H 2 O 2. [ABSTRACT FROM AUTHOR]

Here, we report an organometallic chemistry-assisted method for modification of zinc oxide (ZnO) nanoparticles by tin oxide (SnO 2) nanoparticles, providing a novel and efficient approach for preparation of metal oxides-based heterojunction. The SnO 2 /ZnO heterojunctions were prepared by modification of ZnO nanoparticles with (CH 3) 2 SnCl 2 through organometallic chemistry reaction firstly, and subsequently thermal treatment in air atmosphere. The combined characterizations indicate the successful formation of ZnO/SnO 2 heterojunctions with controllable surface oxygen vacancy concentrations by optimizing organometallic chemistry reactions. Most importantly, ZnO-Sn-0.75-based NO 2 sensor delivers the response of 14.3 toward 0.5 ppm NO 2 at 190 °C with response time of 100 s and recovery time of 101 s. It is also found that ZnO-Sn-0.75 sample exhibits better NO 2 sensing performances than ZnO nanoparticles and other ZnO-Sn samples (ZnO-Sn-0.50, and ZnO-Sn-1.0). The excellent sensing performances of ZnO-Sn-0.75 are attributed to the synergistic effect n - n heterojunction and controllable surface oxygen species. The present work opens a generalized avenue for facile, cheap and mass production of transition metal oxides-based heterojunctions for various applications. [ABSTRACT FROM AUTHOR]

Cobalt oxide (Co 3 O 4 )-based materials have been extensively investigated as efficient electrocatalysts for non-enzymatic glucose biosensing. The proper tuning the structure of Co 3 O 4 -based materials could improve sensing performances for glucose detection. Herein, we have developed a combined self-assembly and calcination method to prepare nanoparticles-assembled Co 3 O 4 nanosheets, which exhibit good sensing performances for glucose biosensing. The Co 3 O 4 nanosheets were prepared by the following three steps: (i) the Co 2+ modified graphene oxide (GO) was prepared by the self-assembly of Co 2+ and GO in aqueous solution firstly, and then Co 2+ modified GO film was obtained by vacuum filtration method; (ii) after calcination of Co 2+ modified GO film in N 2 atmosphere, Co 3 O 4 nanoparticles modified reduced GO (RGO) was obtained; (iii) finally, nanoparticles-assembled Co 3 O 4 nanosheets were obtained by calcination of Co 3 O 4 modified RGO in air to remove RGO template. Most importantly, Co 3 O 4 nanosheets exhibit good electrocatalytic activity for oxidation of glucose, leading to high-performance glucose sensor. The detection limit and linear range of Co 3 O 4 nanosheets-based glucose sensor in the present work are 0.15 μM, and 1–50 μM, respectively. Furthermore, such sensor also shows excellent selectivity for glucose detection, compared to the commonly interfering species including dopamine, and uric acid. [ABSTRACT FROM AUTHOR]

The α-Fe 2 O 3 /SnO 2 -RGO-15 possessed a competitive sensing performance with a high response of 7.4 towards 1 ppm NO 2 at room temperature. [Display omitted] As promising sensing materials, reduced graphene oxide (RGO)-based nanomaterials have drawn considerable attention in the fields of gas monitoring owing to their low operating temperature. However, constructing RGO-based room-temperature gas sensors possessing ppb-level limit of detection with high sensitivity remains challenging. In this work, a series of highly sensitive NO 2 sensors were fabricated using α-Fe 2 O 3 and SnO 2 co-decorated RGO hybrids (designated as α-Fe 2 O 3 /SnO 2 -RGO) as sensing materials. They were rationally synthesized by a one-pot hydrothermal method. Compared to SnO 2 modified RGO hybrids (SnO 2 -RGO with bandgap of 3.88 eV), the bandgap energy of α-Fe 2 O 3 /SnO 2 -RGO hybrids (3.53 eV) was reduced by adding α-Fe 2 O 3; the narrower bandgap facilitated the sensing materials to release more electrons and form more oxygen ions at room temperature. Besides, the high carrier migration of RGO, which served as continuous phase, identical structure with ultrasmall particle size of α-Fe 2 O 3 and SnO 2 (about 3–6 nm), and abundant chemisorbed oxygen species on the surface (20.8%) of the sensing materials, as well as their suitable bandgap (3.53 eV) in the sensing materials, significantly improved NO 2 response at room temperature. Among the sensors fabricated, α-Fe 2 O 3 /SnO 2 -RGO-15-based NO 2 sensor had the highest response of 7.4 with a short response time of 59 s towards 1 ppm NO 2 ; it could even reach a response of 2.6 towards 100 ppb NO 2. Notably, α-Fe 2 O 3 /SnO 2 -RGO-15 sample has excellent capability to recognize NO 2 , where the response value (7.4) towards 1 ppm NO 2 is about 7 times higher than that of 100 ppm ammonia and common volatile organic compounds (formaldehyde, toluene, ethanol and acetone). Such NO 2 sensor has superior repeatability with negligible response deviation towards 1 ppm NO 2 for four reversible cycles. This makes it to have a great potential application in the field of NO 2 detection. [ABSTRACT FROM AUTHOR]

[Display omitted] The metal oxides-based chemiresitive gas sensors have attracted enormous interest because of their exellent sensing perforamcnes, which have emerged as very promising candidates for gas monitoring. However, from the view of organophosphorus compounds detection, a unique combination of low detection limit and fast respons/recovery rate remains challenging. Herein, the synersgitic effects of oxygen vacancy engineering and surface gold decoration enabling excellent sensing performances for detection of dimethyl methyl phosphonate (DMMP, a typical organophosphorus) is reported. To demonstrate the proof of concept, Au nanoparticles (NPs) decorated oxygen vacancy-enriched SnO 2 hybrids (designated as Au-O-SnO 2) were designed as sensing materials, where the O-SnO 2 samples were fabricated by introduction of oxygen vacancies onto commercial SnO 2 through organometallic chemistry-assisted approach using (CH 3) 2 SnCl 2 as precursor, followed by deposition of Au NPs by an in-situ reduction routine. After optimizing Au NPs content in hybrids (1 wt%, 3 wt%, 5 wt% and 7 wt%), O-SnO 2 decorated with 5 wt% Au NPs (designated as Au-O-SnO 2 -5) exhibits excellent DMMP sensing performances, such as, an enhanced recoverable response of 1.67 to 680 ppb DMMP, low detection limit of 4.8 ppb, short response time of 26 s and recovery time of 32 s, as well as good selectivity, which are much better than that of commercial SnO 2 (C-SnO 2) and O-SnO 2 , and Au NPs decorated C-SnO 2. Based on the detailed investigation, the enhanced DMMP sensing performances of Au-O-SnO 2 hybrids can be mainly ascribed to the synergistic effect of increasing surface active sites induced by oxygen vacancies, the chemical and electronic sensitization of Au NPs. As a result, Au-O-SnO 2 -5 hybrids display relatively low activation energy of 24.11 kJ/mol for DMMP oxidization, which is lower than that of O-SnO 2 (35.54 kJ/mol). Our results provide a feasible method for boosting sensing performances for DMMP detection, paving new way for fabrication of metal oxides-based gas sensors for rapid detection of trace organic compounds with complexed structures. [ABSTRACT FROM AUTHOR]

[Display omitted] Application of metal organic frameworks (MOFs) on sensors is of great interest for researchers. Film forming ability of the sensing material is very important for both the preparation process and sensing properties of the devices. Humidity sensors based on UIO-66 derived polyelectrolyte films were well prepared by in situ thiol-ene click cross-linking polymerization in this work. The hydrophilicity of the sensing film could be controlled by the feed ratios. The optimized humidity sensor shows a fast response to RHs change (Res/Rec time is 3.1 s/1.5 s, respectively) with ∼1.2% RH of humidity hysteresis. The water molecules adsorption behavior of the film and the sensing mechanism were also be investigated. The humidity sensor with good water and thermal stability and repeatability was applied in breath monitoring, which can well distinguish different breath states. [ABSTRACT FROM AUTHOR]

Owing to the outstanding dielectric properties derived from the conjugated π-electron systems, conjugated polymers have been explored and developed in capacitive humidity sensors for a few decades. In this work, a series of composites – mesoporous silica and semiconducting polymers – MCM-41 (MCM, Mesoporous Crystalline Material)/PEDOT (poly(3,4-ethylenedioxythiophene)) were chemically obtained by in-situ polymerization at 0 °C, while the amounts of PEDOT were adjusted by different evaporation times of EDOT (3,4-ethylenedioxythiophene) in the porous MCM-41 film. Additionally, it was able to modulate both the dielectricity and porosity of the composites via this convenient approach. The obtained capacitive humidity sensors based on MCM-41/PEDOT composites exhibit much better sensing performance than their bulk counterparts, with wider humidity sensing range, higher sensitivity and much faster response speed. [ABSTRACT FROM AUTHOR]

Graphic abstract In 2 O 3 and zeolitic imidazolate framework-8 (ZIF-8) heterostructures were firstly synthesized and designed as efficient sensing materials for ppb-level NO 2 detection. Abstract The development of NO 2 gas sensors is of great importance for air quality monitoring and human health. In this work, In 2 O 3 and zeolitic imidazolate framework-8 (ZIF-8) heterostructures were synthesized and designed as efficient sensing materials for NO 2 detection. The ZIF-8 nanocrystals were uniformly deposited on In 2 O 3 nanofibers (NFs) by using a self-template strategy, where In 2 O 3 /ZnO NFs act as the source of Zn2+ for the formation of ZIF-8 and as the template. By tuning the amount of Zn2+ in the composite NFs, different morphologies from In 2 O 3 NFs with minimal ZIF-8 loading to an In 2 O 3 /ZIF-8 core-shell complex were obtained. The optimized In 2 O 3 /ZIF-8 NFs show a remarkably high response to 1 ppm NO 2 (R g /R a = 16.4) and enhanced humidity resistance due to the hydrophobicity of ZIF-8 in comparison with those of the pristine In 2 O 3 NF sensor (R g /R a = 4.9) at 140 °C. The gas sensing mechanism of In 2 O 3 /ZIF-8, which is based on electron transduction, surface chemistry, and the functional interface between the loaded ZIF-8 and In 2 O 3 matrix, was proposed. Additionally, the large number of pores, which were formed by the in situ conversion of ZnO grains in the matrix, ensures that all parts of the In 2 O 3 NFs are accessible to gases. This facile strategy paves the way for the design of metal oxide/MOF complex architectures with tunable metal centers for various applications, including gas sensing. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate room-temperature NO 2 gas sensors using Pd nanoparticles (NPs) and SnO 2 NPs decorated reduced graphene oxide (Pd-SnO 2 -RGO) hybrids as sensing materials. It is found that ultrafine Pd NPs and SnO 2 NPs with particle sizes of 3–5 nm are attached to RGO nanosheets. Compared to SnO 2 -RGO hybrids, the sensor based on Pd-SnO 2 -RGO hybrids exhibited higher sensitivity at room temperature, where the response to 1 ppm NO 2 was 3.92 with the response time and recovery time being 13 s and 105 s. Moreover, such sensor exhibited excellent selectivity, and low detection limit (50 ppb). In addition to high transport capability of RGO as well as excellent NO 2 adsorption ability derived from ultrafine SnO 2 NPs and Pd NPs, the superior sensing performances of the hybrids were attributed to the synergetic effect of Pd NPs, SnO 2 NPs and RGO. Particularly, the excellent sensing performances were related to high conductivity and catalytic activity of Pd NPs. Finally, the sensing mechanism for NO 2 sensing and the reason for enhanced sensing performances by introduction of Pd NPs are also discussed. [ABSTRACT FROM AUTHOR]