According to Pmax = V2/(4*ESR), power density (Pmax) is proportional to the applied potential (V2) and equivalent series resistance (ESR). To overcome the limitation of narrow potential window herein, we employed in-situ hydrothermal synthesis of K-delta MnO2 coupled with casein carbon dots (CCDs) decorated Multi-walled carbon nanotubes (MWCNTs) which resulted in enhanced ion/charge conductivity, power density, energy density, porosity, specific surface area (666.387 m2/g), broaden potential window of 0-1.4 V and highly reversible redox pseudo-capacitance of 396 F/g, due to synergistic effect of elevated electrical conductivity of CCDs decorated nanotubes. At a potential window of 1.4 V fast faradic redox reactions and K+ intercalation/deintercalation occur at the electrode-electrolyte interface in MnO2 which constrain water disintegration in kinetics. A high efficacy aqueous asymmetric super capacitor (K-delta MnO2/CCDs-MWCNTs//AC) was configured with K-delta MnO2/CCDs-MWCNTs as anode which manifested steady working potential window of 0-2.4 V in 1 M Na2SO4 aqueous electrolyte. The as configured asymmetric super capacitor has illustrated an outstanding energy density of 82 Wh/kg at a power density of 595 W/kg and specific capacitance of 103 F/g and a prolonged cycle execution with capacitance retention of 98 % over 10,000 cycles at the current density of 0.5 A/g. This approach will open new paradigms for new emerging high feasible wide potential window energy storage devices.

Photoactive colloidal motors whose motion can be controlled and even programed via external magnetic fields have significant potential in practical applications extending from biomedical fields to environmental remediation. Herein, we report a "three in one" strategy in a Co/Zn-TPM (3-trimethoxysilyl propyl methacrylate) bimetallic Janus colloidal micromotor (BMT-micromotor) which can be controlled by an optical field, chemical fuel, and magnetic field. The speed of the micromotors can be tuned by light intensity and with the concentration of the chemical fuel of H2O2, while it could be steered and programed through magnetic field due to the presence of Co in the bimetallic part. Finally, the BMT-micromotors were employed to effectively remove rubidium metal ions and organic dyes (methylene blue and rhodamine b). Benefited of excellent mobility, multiple active sites, and hierarchical morphology, the micromotors exhibit excellent adsorption capacity of 103 mgg(-1) to Rb metal ions and high photodegradation efficiency toward organic dyes in the presence of a lower concentration of H2O2. The experimental characterizations and DFT calculations confirmed the strong interaction of Rb metal ions on the surface of BMT-micromotors and the excellent decomposition of H2O2 which enhanced the photodegradation process. We expect the combination of light and fuel sensitivity with magnetic controllability to unlock an excess of opportunities for the application of BMT-micromotors in water treatments.

The solvothermal and wet chemical method was developed to synthesized the p-n heterostructures of the thin porous Co3O4 nanosheets with ZnO nanoparticles. The resulting products were analyzed by using various characterization techniques. The results possessed that the presence of a large number of oxygen defects on the surface of Co3O4-ZnO-7 favors enhancing the NO2 adsorption. Correspondingly, the formation of p-n heterojunction and the large surface area of the material itself increased the carrier density and exposed more active sites, which collectively boost the sensing performance to NO2. The sensor showed a high response of 45.7 (S = Ra/Rg) to 100 ppm NO2 at room temperature (RT = 25 degrees C), with a short response/recovery time (1.3/25 s), and the lower detection limit of the sensor reached 30 ppb, with good selectivity, reproducibility and stability. This study will offer the opportunity to develop new sensors with high response and fast response-recovery to NO2 at room temperature.

Rapid detection of toxic gases is a crucial and challenging task for industrial production and disease detection. In this work, the B3C2P3 monolayer is found to be an excellent NH3, NO2 and NO sensing material by first-principles calculations. Our results reveal that B3C2P3 exhibits chemical adsorption of NH3 and NO2 and strong physical adsorption of NO, with adsorption energies (Eads) of -0.37 eV, -0.47 eV and -0.22 eV, respectively. Notably, B3C2P3 shows negligible adsorption strength towards gases such as CO, CO2, H2O, H2S, CH4, N-2 and O-2 (Eads > -0.17 eV). The calculated current-voltage curves possess a significant response of B(3)C(2)P(3 )after adsorption of NH3, NO2 and NO and the current value increasing by 3.5, 8.8, and 4.7 folds at the voltage of 0.7 V, respectively. Furthermore, the recovery times of the three gases on the B3C2P3 surface are less than 8.15 mu s at room temperature. Additionally, it is found that the adsorption energy of NH3 on B3C2P3 can be easily regulated by applying strain, which implies that the capture/releases process is reversible. Based on these findings, we propose that B3C2P3 is a promising material for sensing or capturing N-containing gases with high sensitivity, selectivity and reversibility.

Transition metal disulfides (TMDs) have been the subject of extensive research interest in the field of gas sensors due to their distinctive physical and chemical characteristics. However, the insufficient stability and poor moisture resistance, is the two major challenges of these materials in practical applications. In this work, pristine Mo-S bonds were partially transformed into Mo-Se bonds by thermal selenization treatment under H2(5%)/Ar atmosphere conditions to form 3D MoS2-xSex alloy nanocomposites, which the surface of the composites possess a nanoscale and dense convex structure (100-400 nm), similar with the bionic structure of the lotus leaf in morphology. The fabricated MoS2-xSex sensor with lotus-leaf-like structure and large number of sulfur defects revealed high sensitivity (S = 71.2), fast response (4.7 s) and lower limit (50 ppb) to NO2 at room temperature (RT, 25 degrees C). Notably, the unique lotus leaf-like structural design of the MoS2-xSex alloy nanocomposite considerably improves the moisture resistance and enhances its stability in humid environments.

Aerogel with ultra-lightweight, special wettability and porous structure played a potential role in the separation of oil layer/water mixture. In this research cost-effective mesoporous three-dimensional (3D) aerogel was designed and fabricated through a simple and green hydrothermal, synthetic method as a sorbent for efficient treatment of emulsified oil. The-prepared grapefruit peel aerogel exhibits mesoporous structures (2-50 nm) with an average pore size/diameter of 10.21 nm, a surface area of 17.31 m2/g and pore volume up to 0.0321 cm3/g. Excellent hydrophobicity of DMS-MGA aerogel with a water contact angle of 143.1 degrees depicting great potential of this material for effective separation of water-oil emulsion. Furthermore, the prepared aerogel displayed excellent regeneration capability of more than 98% after eight cycles of sorption-regeneration. The carboniza-tion process destroyed graphite crystals, and a new peak confirmed the alteration. PDMS raised crystallinity indices to 86%. Raman spectroscopy also revealed two peaks at 1498 and 1588 cm-1 linked with carbon's D and G bands. The effective grafting of dimethyl siloxane on DMS-MGA surface resulted in two new strong bands in the FT-IR spectra at 1254 cm-1 (C-H in Si-CH3) and 796 cm-1 (Si-O). TGA showed that the total carbon output was 28.5%, which is indicative of its good stability at elevated temperatures. DMS-MGA demonstrated near-complete sorption at a neutral pH of 7 of a crude oil-in-water emulsions. After 15 sorption-regeneration cycles, DMS-MGA still had a sorption efficiency of more than 95% despite being in contact with oil, and its anti-compression stability hadn't changed in the slightest.

Metal–organic frameworks (MOFs) are considered ideal gas-sensing materials owing to their unparalleled tunability, large surface area, rich porosity, and extensive active metal sites.

In this work, a 3D/2D cubic In2O3/Copper doped graphitic carbon nitride (Cu-CN), heterojunction photocatalysts were synthesized using hydrothermal process and further applied to study its photocatalytic properties for bisphenol-A (BPA) degradation. The cubic three-dimensional In2O3 disperse on the surface of Cu-CN two-dimensional sheet was studied by TEM and XRD. The resulting composites of In2O3/Cu-CN, show the highest photocatalytic activity for 15%-In2O3/Cu-CN at optimized ratio under the visible-light irradiation. As compared to both pure Cu-CN and/or In2O3, the optimized composites of In2O3/Cu-CN show 5-7 fold improvement for the degradation of BPA. Specifically, In2O3/Cu-CN with a In2O3/Cu ratio of 15% displays a kinetic value of 0.01/ min, whereas pure Cu-CN and In2O3 have a kinetic value of 0.002/min and 0.0015/min, respectively. The sig-nificant enhancement of the photocatalytic behaviour of the heterojunction is attributed to the regulated In2O3/ Cu-CN, that not only promotes the separation of photo-induced electrons and electron-hole efficiently, but also the transformation of heterojunction interface via the band position in between the Cu-CN and In2O3. Further-more, the improvement mechanism of achievable activity is discussed in details. Moreover, 15%-In2O3/Cu-CN also exhibits a good stability and photocatalytic activity as verified through four recycling responses. It is evi-denced that the superoxide (center dot O-2) and holes (h(+)) play a crucial role as reactive species for the photocatalytic degradation of BPA. This study provides a new opportunity for the preparation of metal oxide/Cu-CN, hetero-junction photocatalysts, which has promising application prospects in wastewater treatment and pollution controlling.

Microorganisms display nonequilibrium predator-prey behaviors, such as chasing-escaping and schooling via chemotactic interactions. Even though artificial systems have revealed such biomimetic behaviors, switching between them by control over chemotactic interactions is rare. Here, a spindle-like iron-based metal-organic framework (MOF) colloidal motor which self-propels in glucose and H2 O2 , triggered by UV light is reported. These motors display intrinsic UV light-triggered fuel-dependent chemotactic interactions, which are used to tailor the collective dynamics of active-passive colloidal mixtures. In particular, the mixtures of active MOF motors with passive colloids exhibit distinctive "chasing-escaping" or "schooling" behaviors, depending on glucose or hydrogen peroxide being used as the fuel. The transition in the collective behaviors is attributed to an alteration in the sign of ionic diffusiophoretic interactions, resulting from a change in the ionic clouds produced. This study offers a new strategy on tuning the communication between active and passive colloids, which holds substantial potentials for fundamental research in active matter and practical applications in cargo delivery, chemical sensing, and particle segregation.

Light-actuated micromachines are of enormous interest due to their ability to harvest light for triggering catalytic reactions to acquire free energy for mechanical work. This work presents an inorganic-organic hybrid copolymeric poly(cyclotriphosphazene-co-barbituric acid) colloid, which displays multiwavelength excited emission and catalytic activities, exploiting the unique structural, chemical, and optical features of inorganic heterocyclic ring hexachlorocyclotriphosphazene and organic co-monomer barbituric acid. Specifically, this work reveals particle-resolved unusual multicolor emission under excitation with the same or different wavelengths of light using fluorescence microscopy. The result is rationalized by density functional theory studies. In this work, the authors find that emission is coincident with fluorometric measurements, and the photocatalytic properties are anticipated from the overall band structure. This work also demonstrates the use of these colloids as micropumps, which can be remotely activated by UV, blue, and green lights under fuel-free conditions, and ascribe the behavior to ionic diffusiophoresis arising from light-triggered generation of H+ and other charged species. This work offers a new class of polymeric colloids with multiple-wavelength excited emission and catalytic activities, which is expected to open new opportunities in the design of fuel-free, photo-actuated micromachines and active systems.

Both 3-hydroxy-2-butanone and triethylamine are highly toxic and harmful to human health, and their chronic inhalation can cause respiratory diseases, eye lesions, dermatitis, headache, dizziness, drowsiness, and even fatality. Developing sensors for detecting such toxic gases with low power consumption, high response with superselectivity, and stability is crucial for healthcare and environmental monitoring. This study presents a typical gas sensor fabricated based on AuPdO modified Cu-doped K2W4O13 nanowires, which can selectively detect 3-hydroxy-2-butanone and triethylamine at 120 and 200 °C, respectively. The sensor displays excellent sensing performance at reduced operating temperature, high selectivity, fast response/recovery, and stability, which can be attributed to a synergistic effect of Cu dopants and AuPdO nanoparticles on the K2W4O13 host. The enhanced sensing response and selectivity could be attributed to the oxygen vacancies/defects, bandgap excitation, the electronic sensitization, the reversible redox reaction of PdO and Cu, the cocatalytic activity of AuPdO, and Schottky barrier contacts at the interface of tungsten oxide and Au. The significant variations in the activation capacities of Cu-doped K2W4O13, Pd/PdO, and Au nanoparticles toward 3H-2B and TEA, and the diffusion depth of the two gases in the coated sensing layer may cause dual selectivity. The designed gas sensor materials can serve as a sensitive target for detecting toxic biomarkers and hold broad application prospects in food and environmental safety inspection.

Two-dimensional ultrathin MXenes (Ti3C2Tx) have gained crucial attention in the field of gas sensing owing to their unique chemical and physical properties.

Light-powered fuel-free colloidal motors possess significant potential for practical applications ranging from nanomedicine to environmental remediation. However, current light-powered colloidal motors often require the incorporation of expensive metals or high concentrations of toxic chemical fuels, which is a severe limitation for their practical applications. Integrating highly ordered and porous materials with a large surface area into colloidal motors is a promising strategy for upsurging their self-propelled speed and adsorption, which will benefit many applications. Here, highly efficient, fuel-free, and light-activated metal organic framework (MOF)-3-trimethoxysilyl propyl methacrylate Janus colloidal motors with a hierarchical morphology are reported. These colloidal motors can be driven by UV or visible light, with a self-propelled speed tuned by the light intensity. The speed can be further enhanced by morphology optimization or by the addition of H2O2 as a fuel. The colloidal motors display a superior efficiency in removing heavy metal ions of Hg, which is up to ∼90% within 40 min from the contaminated water, attributed to their high surface area, hierarchical morphology, large number of active sites, and high mobility. This work not only offers a facile approach to incorporate a versatile MOF family into the design of fuel-free and light-powered Janus colloidal motors, but also demonstrates their potential for real-life applications such as environmental remediation.

A hydrothermal method was developed to convert rhombic p–p MoS2@ZIF-8 into a rodlike p–n MoS2@ZnO heterostructure with a large surface area for sensitive detection of NO2 at room temperature.

Controllable synthesis of ZIF-67/EG intercalated structure for detection of ultra-trace Cd2+, Cu2+, Hg2+ and Pb2+ ions.

SnS2 nanosheets (NSs) have become an ideal candidate for high performance gas sensors due to their unique sensing properties. However, the restocking and aggregation in the process of sensor manufacturing have great influence on the gas sensing performance. In this study, we synthesized a novel heterojunction of the flower-like porous SnS2 NSs with edge exposed MoS2 nanospheres via a facile hydrothermal method and sensitive response has achieved at room temperature (27 degrees C). After functionalization, the SMS-II showed excellent response (Ra/Rg = 25.9-100 ppm NO2), which is 22.3 times higher than that of the pristine SnS2 NSs. The sensor also has the characteristics of short response time of 2 s, excellent base line recovery (28.2 s), long-term stability and reliability within 16 weeks, good selectivity and low detection concentration of only 50 ppb. The p-n heterojunction formed between the edge-exposed spherical MoS2 and the 3D flower-like SnS2 NSs has a synergistic effect, providing a highly active sites for the adsorption of NO2 gas, which greatly enhance the sensitivity of the sensor. Simple fabrication and excellent gas sensing performance of the SnS2/MoS2 heterostructure nanomaterials (NMs) will highly effective for commercial gas sensing application.

In this paper, intercalated CuO/BP nanocomposites (NCPs), with small and extremely dispersed CuO nanoparticles (NPs) on pyrrole (Py)-modified expanded black phosphorus (BP) nanosheets (NSs), were synthesized by a simple hydrothermal method. In the synthesis process, the expanded BP is first expanded with diethylene glycol dimethyl ether, and then following CuO NPs growth, the Cu(CH3COO)(2)center dot H2O precursor is completely injected into the middle layer of the Py modified expanded BP NSs (Py-EBP) under vacuum. The CuO/BP NCP inserted under hydrothermal conditions is formed in situ in the intermediate layer of the Py-EBP NSs. Intercalating CuO/BP-190 NCP with 4-5 nm CuO NPs for 5 h at 190 degrees C yields a high sensitivity of 20.7, rapid response of 4 s, superior selectivity and wide range of target NO2 gas sensing from 100 ppm to 10 ppb at room temperature (RT) in air. Therefore, the method developed in this work is of great significance for easy synthesis and large-scale production of stable CuO/BP NCP and has great prospects for applications in gas sensors.

In this study, the hydrothermal and Chemical Vapor Deposition (CVD) methods were applied to synthesize the Ni9S8/NiAl2O4 (NAS) nanocomposites by in situ using NiAI-LDH (NA) as a template. A series of structural and morphological features show that the NAS 2-1 nanocomposite (NC) with the three-dimensional (3D) flower-like structure which is composed of ultrathin nanosheets (4.1-4.9 nm) and porosity (about 2 nm). The NAS 2-1 (NA:S mass ratio 1:6) NC sensor exhibited the excellent response (20.30) with ultrafast response time (1.06 s) to 100 ppm NOx at room temperature (RT), and the detection limit can reach to 10 ppb, respectively. The superior gas sensitivity of the NAS 2-1 sensor is primarily due to the particular three-dimensional flower-like nanostructures and the synergy between Ni9S8 and NiAl2O4. The NAS 2-1 sensor is expected to be used as a gas sensing material due to its excellent three-dimensional flower-like structure and outstanding properties at RT. (C) 2020 Elsevier B.V. All rights reserved.

S-Doped biomorphic SnO2 with active S-terminations and S–Sn–O chemical bonds has significantly improved gas sensing performance to NO2 at room temperature.

Biomorphic SnO2 nanoparticles with a mesoporous structure were synthesized using simple one-step hydrothermal method with SnCL2 as the raw material and hemp stems as the bio-template. The uniformly grown SnO2 nanoparticles perfectly inherited the 3D structure of biomass carbon and formed a rich mesoporous structure, which was beneficial to gas sensing and facilitated the transport of the target gas on the surface and inside the sample. Moreover, the high surface area of materials provides more active sites for the adsorption of oxygen and the target gas. The sample with a 450 degrees C annealing temperature exhibited an excellent response (35.83) as a NO2 sensor at room temperature (RT), fast response speed to 100 ppm NO2 (2.67 s), and a detection limit as low as 10 ppb. Furthermore, it displayed long-term stability, excellent selectivity and good repeatability. Therefore, the mesoporous biomorphic SnO2 nanoparticles represent a good candidate as a key green material for an NO2 sensor at RT.