Search

Graphical abstract Eggplant-derived carbon flakes with ultrahigh surface area were used as substrate for the confined growth of NiCo 2 S 4 nanosheets, which exhibited excellent capacitive performance. Highlight • Porous carbon flakes with ultrahigh surface area were prepared from eggplant. • NiCo 2 S 4 nanosheets were vertically grown within the carbon flakes. • The composite showed excellent supercapacitive performance. Abstract Transition metal oxides and compounds have been extensively investigated as electrode materials for high-performance supercapacitors. However, the poor rate performance and cyclic stability of these materials have hindered their practical applications. Herein, carbon flakes with an ultrahigh surface area (3608.4 m2 g−1) prepared from eggplant were used as substrates to enhance the electrical conductivity and overall capacitive performance of NiCo 2 S 4 nanosheets. The composite exhibited a high specific capacitance (1394.5 F g−1 at 1 A g−1) which was 50% higher than that of the bare NiCo 2 S 4 (989.8 F g−1 at 1 A g−1) and four times that of the eggplant-derived carbon (327 F g−1 at 1 A g−1). It also exhibited excellent rate capability (80.2% retention from 1 to 20 A g−1) and cyclic stability (124% retention after 10,000 cycles). These results were achieved by optimizing the pyrolysis of eggplant and the hydrothermal process which led to the confined growth of NiCo 2 S 4 nanosheets on the carbon flakes due to coordination of Ni2+ and Co3+ cations to the polar groups of the carbon. The flake morphology, oxygen and nitrogen-rich surface and the ultrahigh surface area of the eggplant-derived carbon were found to be crucial for the well separation of NiCo 2 S 4 nanosheets and consequently the excellent overall performance. Furthermore, asymmetric supercapacitors were constructed using the composite as the cathode and eggplant-derived carbon as the anode, which delivered a maximum energy density of 46.5 W h kg−1 at a power density of 801 W kg−1 and retained an energy density of 26.2 W h kg−1 at a maximum power density of 16 kW kg−1. [ABSTRACT FROM AUTHOR]

A novel MOF-based S-scheme heterostructure of MIL101-(Fe)/Bi 2 WO 6 was designed and synthesized for efficient photocatalytic elimination of Cr(VI) and antbiotic tetracycline hydrochloride by virtue of the abundant reactive sites and OV-mediated S-scheme photo-carrier separation mechanism. [Display omitted] • A dual dual-functional photosystem of defective MIL-101(Fe)/Bi 2 WO 6 S-scheme heterojunction was designed. • MIL-101(Fe)/Bi 2 WO 6 showed excellent activity for removal of Cr(VI) and tetracycline under visible light. • The high specific surface area and OV-mediated S-scheme structure contribute to the excellent photocatalytic performance. • The degradation process of tetracycline and eco-toxicity of the intermediates were investigated. Solar-driven elimination of refractory contaminants is an ideal route to tackle the environmental issues. Nevertheless, the photocatalytic performance of photocatalysts is heavily restrained due to the insufficient accessible reactive sites and fast electrons/holes reunion. Herein, a novel metal–organic framework-based S-scheme heterostructure of MIL-101(Fe)/Bi 2 WO 6 was synthesized by a simple solvothermal approach. The optimized MIL-101(Fe)/Bi 2 WO 6 (MIL/BWO-2) affords the highest photo-activities under visible light, which are 13.7, 6.7 folds greater for Cr(VI) reduction, and 0.8, 10.5 folds higher for tetracycline hydrochloride oxidation compared with individual Bi 2 WO 6 and MIL-101(Fe), respectively. The preeminent catalytic capability lies in two aspects: 1) the introduction of MIL-101(Fe) substantially enlarges the surface area of the composites, offering ample reaction sites and fostering pollutant adsorption and mass transportation; 2) the novel S-scheme photo-carrier transport mechanism assisted by oxygen vacancies favors spatial segregation and transport of photoinduced electrons/holes with superior redox capacity. Reactive species identification experiments verify that O 2 – and e– dominantly contribute to Cr(VI) reduction, while O 2 –, h+ and OH account for tetracycline hydrochloride destruction. Furthermore, the tetracycline photo-decomposition pathway, eco-toxicity evaluation, and photocatalytic mechanism were investigated comprehensively. This research paves the way for building high-performance MOFs-based S-scheme heterojunctions toward photocatalytic water purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • 0D/3D Bi 2 Sn 2 O 7 /Bi 2 MoO 6 S-scheme heterojunction was constructed. • The heterojunction exhibited excellent photocatalytic performance for antibiotics. • A plausible degradation pathway for TC was proposed. • S-scheme heterojunction largely boosted charge separation and ROS production. The fabrication of step-scheme (S-scheme) heterojunction with superior redox capability has been emerging as a prospective strategy for environmental remediation. Herein, novel Bi 2 Sn 2 O 7 /Bi 2 MoO 6 S-scheme heterojunctions have been fabricated via in-situ anchoring Bi 2 Sn 2 O 7 nanoparticles on Bi 2 MoO 6 microspheres. The optimized Bi 2 Sn 2 O 7 /Bi 2 MoO 6 (BSO/BMO-6%) attains the highest reaction rate constant (k) in the degradation of tetracycline hydrochloride (TC, k = 0.0397 min−1), which is 3.62 folds higher than that of pristine Bi 2 MoO 6. Such an improvement is originated from more exposed active sites, higher photo-excited charge separation efficiency, superior redox ability, and efficient production of reactive h+, •OH and •O2–. Besides, Bi 2 Sn 2 O 7 /Bi 2 MoO 6 could efficiently degrade the TC antibiotic in actual water matrix. Significantly, the toxicity evaluation verifies the nontoxicity of Bi 2 Sn 2 O 7 /Bi 2 MoO 6. Moreover, the degradation pathways of TC are determined and the toxicity of degradation intermediates is appraised by using HPLC-MS spectra and QSAR prediction. A possible photocatalytic mechanism over S-scheme Bi 2 Sn 2 O 7 /Bi 2 MoO 6 has been elucidated based on experimental studies combined with density functional theory (DFT) calculations. This work offers new insights for the design of high-performance S-scheme heterojunctions for environmental remediation. [ABSTRACT FROM AUTHOR]

A new 3D Ag/Ag 2 S/Bi 2 MoO 6 plasmonic p-n heterojunction photocatalyst has been designed and applied for efficiently visible-light photocatalytic degradation of pharmaceutical antibiotics. [Display omitted] • Ag/Ag 2 S/Bi 2 MoO 6 (AAS/BMO) plasmonic p-n heterojunction was constructed. • AAS/BMO displayed superior catalytic activity and great stability for antibiotics removal. • Effects of various factors on levofloxacin removal were studied systematically. • A plausible degradation pathway for levofloxacin was proposed. • Plasmonic p-n heterojunction greatly promotes charge separation and ROS production. A novel Ag/Ag 2 S/Bi 2 MoO 6 plasmonic p-n heterojunction has been constructed via the in-situ growth of p-type Ag 2 S nanoparticles on n-type Bi 2 MoO 6 microspheres, followed by the photo-reduction treatment. Simultaneously, the Ag0 loading percentage in the heterojunction could be finely controlled by tuning the photo-reduction time. The optimized Ag/Ag 2 S/Bi 2 MoO 6 (AAS/BMO-4) manifests the highest photocatalytic performance towards degrading levofloxacin (LEV) and tetracycline hydrochloride (TC), which degradation efficiencies are 87.3% and 92.8%, respectively. Such improvement mechanism could be due to the improved light absorption in the visible-light region induced by localized surface plasmon resonance (LSPR) and the efficient interfacial separation and transport of charge carriers in Ag/Ag 2 S/Bi 2 MoO 6. The impacts of some key parameters (e.g., various inorganic anions, representative organic substances and various water resources) are systematically investigated. Ag/Ag 2 S/Bi 2 MoO 6 also exhibits excellent mineralization capability and recycling performance in degrading LEV. Moreover, photo-generated h+, OH, and O 2 – are identified as the dominant reactive species accounting for the degradation of antibiotics. The photodegradation pathway of LEV has also been elucidated based on the intermediate identification. Therefore, this study not only reports an innovative plasmonic p-n heterojunction but also the new design of photocatalysts capable of efficiently degrading pharmaceutical antibiotics under visible-light irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • This work develops a strain sensor that is insensitive to humidity and temperature changes. • The sensor shows a linear sensing feature throughout the whole sensing range. • It provides a new route for enhancing the sensing reliability of wearable sensors. Wearable and stretchable strain sensors have attracted much attention for their unique applications in monitoring human motion and health. However, state-of-the-art sensors lack sensing reliability on temperature and humidity changes at the wearable microinterface, leading to suboptimal sensing accuracy in body area sensing networks. For that, we design and fabricate a strain sensor using silk/polyurethane composite yarns with a core-sheath structure. The silk is modified using graphene with the assistance of 3-glycidyloxypropyl trimethoxy silane as coupling agent. The sensor exhibits fast response speed (i.e., 80 ms), high durability (>1500 cycles), remarkable linear sensing feature (R2 = 99.8 %) throughout the whole working range, and negative resistance response towards strain deformation. More importantly, the sensor performance will not be affected by temperature and humidity changes in typical use conditions. Testing is conducted and sensor responses in various body motions are also reported. In addition, a demonstration for the real-time body area sensing network using the fabricated sensor is provided. Experimental results from this study show that the fabricated strain sensor will have huge potentials for future personalized healthcare and public health management. [ABSTRACT FROM AUTHOR]

Controlling conditions to obtain different acidogenic fermentation types in a two-phase anaerobic co-digestion were investigated for improving the bio-methane yield from food waste (FW) and rice straw (RS). The results showed that the fermentation type in the acidogenic phase could be transformed by changing oxidation–reduction potential (ORP), pH, and organic loading rate (OLR). Three kinds of fermentation types were observed in acidogenic phase. Ethanol-type fermentation occurred at pH < 4.5 and ORP < −120 mV. Butyric acid-type fermentation appeared in the condition of pH > 5.0 with lower ORP and OLR ⩽ 6 g VS/L d. Mixed type fermentation was found in the transformation between butyric acid-type fermentation and ethanol-type fermentation. Among three fermentation types, the butyric-type fermentation achieved the highest acidification degree of 36%, biomethane yield of 535 mL CH 4 /g VS, and biodegradability of 95%. The finding indicated that controlling fermentation type of acidogenic phase could be one of effective method for achieving high biomethane production. [ABSTRACT FROM AUTHOR]

[Display omitted] • TaON/Bi 2 MoO 6 core–shell S-scheme heterojunction nanofibers were constructed. • TaON/Bi 2 MoO 6 exhibited high catalytic activity for LEV and Cr(VI) removal. • The LEV degradation pathway and the detoxification performance were analyzed. • TaON/Bi 2 MoO 6 boosts charge separation, redox capability and ROS production. Developing excellent photocatalysts for antibiotics degradation and Cr(VI) reduction is of vital significance but still a big challenge. Herein, novel S-scheme heterojunction of TaON/Bi 2 MoO 6 with a core–shell structure is constructed via an electrospinning-calcination-nitridation approach, where 2D Bi 2 MoO 6 nanosheets are uniformly and firmly anchored on the surface of 1D TaON nanofibers. The optimal TaON/Bi 2 MoO 6 with the TaON/Bi 2 MoO 6 molar ratio of 1:1 manifests the highest catalytic activity towards levofloxacin (LEV) antibiotic degradation and Cr(VI) reduction under visible light. The exceptional photocatalytic performance is probably due to the synergistic effect of the favorable core–shell fiber-shaped structure and S-scheme hetero-structure, which enables the strong interfacial interaction between the constituents for effectively improving the visible-light absorption, boosting the separation and utilization efficiency of electron-hole pairs, and retaining the charge carriers with stronger redox capabilities. Of note, TaON/Bi 2 MoO 6 possesses excellent stability and reusability. Photo-generated h+, •OH, and •O 2 – are the main reactive species accounting for LEV degradation, the detailed LEV degradation pathways are elucidated by detecting the intermediates using HPLC–MS and the toxicity of the intermediates are assessed by quantitative structure–activity relationship (QSAR) method. In addition, •O 2 – and e– are primarily responsible for Cr(VI) reduction. Further, a possible photocatalytic reaction mechanism for removal of LEV and Cr(VI) is proposed. This study provides some insights in fabricating high-performance S-scheme heterojunction photocatalysts for the efficient water purification. [ABSTRACT FROM AUTHOR]