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Microbial extracellular electron transfer (EET) plays a vital role in globally important environmental phenomena, including bioremediation, bioenergy generation, and biofuel production. The quantitation of microbial exoelectrogenic ability is fundamental to studying the process of EET. However, there is no accurate and time-saving protocol to directly evaluate EET ability, hindering our understanding and application of EET. In this work, we proposed an accurate and rapid quantitation system for measuring EET ability using a gold-coated membrane filter as a working electrode. The quantitation signals could be recorded within 1 h and accurately normalized by the number of cells with outstanding repeatability and reproducibility. Further, this method could be distinguished microbial direct EET performances of different growth stages, and the results showed the middle logarithmic growth stage of Shewanella onedensis MR-1 had the best electrochemical activity. This method can be widely used for different types of electroactive microorganisms, including gram-negative bacteria, gram-positive bacteria, and fungi. Due to its time savings, accurate quantification and easy operation, this method provides a standard way to assess the role of EET ability. • RQEET combined the features of filtration and conductivity to obtain a new type of electrode. • RQEET can quantify microbial EET ability in a short time (≤1 h). • RQEET shows great repeatability by controlling the number and growth stage of loading cells. • RQEET is flexible to integrate into biological techniques for molecular studies. [ABSTRACT FROM AUTHOR]

Pharmacologically active compounds found in reclaimed wastewater irrigation or animal manure fertilizers pose potential risks for agriculture. The mechanism underlying the effects of ketoprofen on rice (Oryza sativa L.) seedlings was investigated. The results showed that low concentrations (0.5 mg L−1) of ketoprofen slightly stimulate growth of rice seedlings, while high concentrations can significantly inhibit growth by reducing biomass and causing damage to roots. Ketoprofen affects photosynthetic pigment content (Chla, Chlb, and carotenoids) and chlorophyll synthesis gene (HEMA, HEMG, CHLD, CHLG, CHLM, and CAO) expression. Fluorescence parameters such as minimum fluorescence (F 0), maximum fluorescence (F m), variable fluorescence (F v), potential photosynthetic capacity (F v /F 0), maximum quantum efficiency of PSII photochemistry (F v /F m), electron transfer rate (ETR), and Y(II), Y(NPQ), Y(NO) values were affected, showing photosynthetic electron transfer was blocked. Active oxygen radical (O 2 •−and H 2 O 2), malondialdehyde and proline content increased. Superoxide dismutase, catalase and ascorbate peroxidase activities, glutathione content and antioxidant-related gene (FSD1, MSD1 , CSD1, CSD2, CAT1, CAT2, CAT3, APX1, APX2) expression were induced. Higher integrated biomarker response values of eight oxidative stress response indexes were obtained at higher ketoprofen concentrations. Ultrastructure observation showed that ketoprofen causes cell structure damage, chloroplast swelling, increase in starch granules, and reduction in organelles. This study provides some suggested toxicological mechanisms and biological response indicators in rice due to stress from pharmacologically active compounds. Image 1 • Ketoprofen affects chlorophyll content, gene expression and electron transfer. • Antioxidant enzymes activity and antioxidant-related gene expression increased. • Has higher IBR value of oxidative stress response indexes at higher concentration. • Cell structure of shoot and root was damaged by ketoprofen. The mechanism of photosynthesis and oxidative stress response of rice caused by ketoprofen were revealed. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction of NO x with ammonia (NH 3 -SCR) under the exposure of multiple poisons in fly ash remains a great challenging issue for environmental protection. Herein, the intelligently self-tunable defense effects of Ce(SO 4) 2 additive modification for the V 2 O 5 /CeO 2 catalyst with excellent resistance against K and Zn co-poisoning was originally illustrated. The Ce(SO 4) 2 additive could firstly act as an inhibitor to certainly restrain the electron transfer between V and Ce species to decrease the redox property, but the high NO x reduction efficiency of Ce(SO 4) 2 modified fresh catalyst could be maintained due to the enhancement of vanadium species polymerization and acidity. Unexpectedly, the Ce(SO 4) 2 additive would smartly translate to act as a promoter over the co-poisoned catalyst to effectively combine with poisons, thus releasing most active vanadium species to exhibit superior co-poisoning resistance to K and Zn. This work provides a novel self-tunable multi-poisoning-resistant strategy via acid additive modification for SCR catalysts. [Display omitted] • Ce(SO 4) 2 modified vanadia catalyst was obtained to fight K and Zn co-poisoning. • Ce(SO 4) 2 modification greatly improved NO x conversion and co-poisoning resistance. • Ce(SO 4) 2 was inhibitor to restrain electron transfer between active V and Ce sites. • Ce(SO 4) 2 translates to promoter to fix K and Zn poisons among poisoned catalysts. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous Zn//MnO 2 batteries are the promising alternatives to lithium-ion batteries owing to their high safety, high energy density, low cost, and environmental friendliness. However, the unstable MnO 2 cathode causes poor practical energy density and serious capacity fading. To overcome this issue, herein, a unique 2D nanosheets self-supported 3D δ -MnO 2 microflower hierarchical architecture is rationally designed and synthesized by taking advantage of its microwave-absorbing characteristics. The 2D nanosheets with high surface area could expose numerous active sites for ions/electrons transfer. Also, the 3D assembled structure acting as building blocks would ensure structural stability for long-life cycles. Benefiting from these synergistic merits, the δ -MnO 2 microflowers deliver a high capacity of 287.6 mA h g−1 at 0.5 C, an excellent rate capability of 202.7 mA h g−1 at 5 C, and a superior cycling retention of 76.5% over 1000 cycles at 10 C. Furthermore, a storage mechanism of H+/Zn2+ co-insertion accompanied by the deposition of zinc sulfate hydroxide hydrate is clarified by the aid of ex-situ XRD and SEM technologies. This work provides a new pathway for developing high capacity and long lifespan ZIBs. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract A sandwich-type photoelectrochemical (PEC) immunosensing platform was designed for detection of amino-terminal pro-B-type natriuretic peptide (NT-pro BNP). Thereinto, flower-like Bi 2 WO 6 /Ag 2 S nanoparticles (F-Bi 2 WO 6 /Ag 2 S) were employed as photoelectrochemical matrix, and graphene oxide and polydopamine composite (GO/PDA) were prepared as signal labels. In this proposal, Ag 2 S was in-situ growth on the surface of F-Bi 2 WO 6 modified with thioglycolic acid (TGA). Specially, a cascade-like band-edge level between F-Bi 2 WO 6 and Ag 2 S effectively improved the photocurrent conversion efficiency and enhanced the photocurrent response. Then, the conjugated GO/PDA aimed to further amplify signal because PDA as electron donor could sweep the holes and inhibit the recombination of photogenerated electron-hole pairs, while GO owned brilliant conductivity speeding up the electrons transfer. The photocurrent increased with the amount of GO/PDA conjugates which had positive correlation with the NT-pro BNP. Under optimal experimental conditions, the proposed sandwich-type PEC immunosensor presented a desirable linear relationship ranged from 0.1 pg/mL to 100 ng/mL for NT-pro BNP with the detection limit of 0.03 pg/mL (S/N = 3). The prepared PEC immunosensor exhibited high stability and selectivity, which offered an innovative idea for the detection of other biomolecules. Highlights • A sandwich-type PEC immunosensor was fabricated for NT-pro BNP detection. • F-Bi 2 WO 6 loaded with Ag 2 S was used as photoactive matrix. • GO/PDA was first utilized as label for signal amplification. • The PEC immunosensor exhibited a low detection limit of 0.03 pg/mL. [ABSTRACT FROM AUTHOR]

The use of metal-free graphite carbon nitride (CN) to activate peroxymonosulfate (PMS) has attracted extensive attention for organic pollutants degradation. In this work, we prepared carbonized polydopamine-decorated g-C 3 N 4 (CP-700) for activation of PMS to degrade norfloxacin (NOR). The CP-700 composite was obtained by using CN as a base material on which dopamine underwent an autopolymerization reaction to form a CN-PDA complex, followed by pyrolysis. The apparent porous structure and graphitization provided a large number of active sites for catalytic degradation, enabling CP-700 to exhibit excellent catalytic performance during PMS activation. The degradation of NOR was not hindered by sulfate radical (SO 4 •–) and hydroxyl radical (•OH). Singlet oxygen (1O 2) and mediated electron transfer were ultimately identified as the primary mechanisms. According to the linear positive correlation (R2 = 0.9922) between the semi-quantitative carbonyl group (C O) and the reaction rate constant, it was determined that the carbonyl group served as the important active site. The excellent electron transfer ability of CP-700 was evidenced by electrochemical techniques and the electron transfer pathway in the system was that PMS was adsorbed on the CP-700 surface to form metastable complex, and then the electron transfer between NOR and metastable complex was achieved. Based on the non-radical pathway, CP-700/PMS system showed a high tolerance to solution pH (3.0–11.0) and inorganic anions. The cyclic degradation experiments indicated that the system maintained a high degradation capability without the addition of additional CP-700, elucidating its potential application in the degradation of organic pollutants in the water. [Display omitted] • CP-700 had a better catalytic reactivity than CN-700 at a lower dosage. • 1O 2 was the primary reactive oxygen species responsible for NOR degradation. • Carbonyl groups and graphitic N served as the main active sites for PMS activation. • CP-700/PMS system exhibited excellent pH tolerance and more effective use of PMS. [ABSTRACT FROM AUTHOR]

[Display omitted] • An anti-perovskite Ni 3 FeN/VN heterostructure is designed for Zn-air batteries. • The anti-perovskite Ni 3 FeN with the metallic behavior contributes to electron transfer. • Abundant catalytic active sites are formed at the heterogeneous interface. • The Ni 3 FeN/VN–NG displays excellent bifunctional activity with a ΔE value of 0.69 V. High-performance rechargeable zinc–air battery is highly relying on the efficient and stable bifunctional electrocatalysts. Herein, an anti-perovskite Ni 3 FeN/VN heterostructure encapsulated N–doped graphene (Ni 3 FeN/VN–NG) was synthesized by a two-step transformation of trimetallic NiFeV–layered double hydroxide. The Ni 3 FeN/VN–NG showed excellent bifunctional catalytic activity (ΔE = 0.69 V) and stability. The excellent bifunctional electrocatalytic performance is benefited from the extraordinary catalytic behavior of Ni 3 FeN/VN heterostructure. The intrinsic metallic properties and remarkable superconductivity of anti-perovskite Ni 3 FeN can enhance the electrocatalytic performance. Density functional theory calculations confirm that the electronic coupling between Ni 3 FeN and VN facilitates the charge transfer between the two components, simultaneously generates abundant catalytic active sites at the heterogeneous interface. When the Ni 3 FeN/VN–NG was used as the air cathode, in zinc–air battery, the zinc–air battery exhibits a high-power density of 168 mW cm−2 and a long cycle life of over 200 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • A self-adhesive tannin–graphene supramolecular pH-sensitive material is proposed. • The material adheres well to various solid and soft substrates. • The sensor exhibits reversible, Nernstian and selective pH responses. • The material can be printed directly to fabricate a wearable sensor for sweat pH monitoring. The pH of sweat is the most common biochemical parameter monitored by integrated wearable devices. A crucial factor in sensing materials for wearable applications is strong contact both with the skin and with the electrode substrate. Currently, the deposition of many sensitive materials on a substrate relies on mixing a small amount of binder, which raises the issue of biocompatibility and the risk of detachment. Herein, we report self-adhesive tannin–graphene supramolecular aggregates for use in wearable potentiometric pH sensors. The abundant phenolic hydroxyl groups in tannin (TA) result in strong adhesion and are also the pH response sites. The graphene (reduced graphene oxide, RGO) induces the supramolecular formation of TA and promotes electron transfer based on the π-π conjugation interaction. The pH sensor has a reversible and Nernstian response, and is not affected by potentially interfering ions. Owing to the strong adhesion of TA–RGO, a wearable pH device was directly fabricated using a dispensing printing technique. The sensor has been shown to be successful in monitoring the pH of sweat in real time. This work emphasizes the importance of the adhesion of sensing materials for use in wearable electrochemical sensors. [ABSTRACT FROM AUTHOR]

A series of N-doped graphitic carbons with different carbonization temperatures (denoted as ENGC-T) are controllably synthesized. The correlation between different N-doping species and interlayer spacing is explored, and thus demonstrating that pyrrolic-N (N-5) content has a substantial effect of the expanded interplanar spacing. The resulting ENGC-850 with the optimal N-5 configuration achieves excellent electrochemical performance in terms of capacity, rate capability, and cycling stability. [Display omitted] • A series of N-doped graphitic carbons are controllably synthesized. • High edge-N doping ratio is conducive to promote capacitive-controlled K-storage. • Pyrrolic-N configuration has a substantial effect on the interlayer spacing. • The resultant product delivers excellent rate capability and exceptional cyclability. Nitrogen (N) doped graphitic-carbon materials as anode have been intensively studied for potassium-ion batteries (PIBs). However, insufficient N-doping content, especially the low edge-N ratio composed of pyridinic-N (N-6) and pyrrolic-N (N-5) cannot provide excellent rate capability and ultra-long cycle lifespan. Meanwhile, the intercorrelation between N-doping species and enlarged interlayer spacing remains unclear and needs to be further explored. Based on this, a series of N-doped graphitic carbons with different carbonization temperatures (denoted as ENGC-T) are controllably synthesized. It is found that a high edge-N doping ratio is conducive to increase active sites to promote capacitive-controlled K-storage. And the correlation between N-doping species and interlayer spacing reveals that N-5 configuration has a substantial effect on the interlayer spacing, due to its stronger electrostatic repulsion. Accordingly, the resultant ENGC-850 with both an ultra-high edge-N ratio (76.6%) and N-5 content (42%) achieves the most abundant defects and the largest interspacing, ensuring high capacity and cycling stability. Besides, good crystallization characteristics guarantees fast electron transfer, favoring conductivity. As expected, ENGC-850 electrode delivers high capacity, excellent rate (228.9 mAh g−1 at 2 A g−1), and prolonged cycle lifespan (188.9 mAh g−1 over 2200 cycles). [ABSTRACT FROM AUTHOR]

To explore a green, low-cost, and efficient strategy to synthesis reduced graphene oxide (RGO), the process and mechanism of the graphene oxide (GO) reduction by a model electrochemically active bacteria (EAB), Geobacter sulfurreducens PCA, were studied. In this work, up to 1.0 mg mL−1 of GO was reduced by G. sulfurreducens within 0.5–8 days. I D /I G ratio in reduced product was similar to chemically RGO. After microbial reduction, the peak which corresponded to the reflection of graphene oxide (001) disappeared, while another peak considered as graphite spacing (002) appeared. The peak intensity of typical oxygen function groups, such as carboxyl C–O and >O (epoxide) groups, diminished in bacterially induced RGO comparing to initial GO. Besides, we observed the doping of nitrogen and phosphorus elements in bacterially induced RGO. In a good agreement with that, better electrochemical performance was noticed after GO reduction. As confirmed with differential pulse voltammetry (DPV) and cyclic voltammetry (CV) analysis, the maximum value of peak currents of bacterially induced RGO were significantly higher than those of GO. Our results showed the electron transfer at microbial cell/GO interface promoted the GO reduction, suggesting a broader application of EAB in biological mediated production of RGO. Image 1 • Provided a green chemistry strategy for the biological production of reduced graphene oxide (RGO) by Geobacter. • Bacterially induced RGO by Geobacter exhibited a good performance in electrochemical conductivity. • The doping of nitrogen and phosphorus elements were observed in the bacterially induced RGO by Geobacter. • Extracellular electron transfer at microbial cell/GO interface promoted the graphene oxide (GO) reduction of Geobacter. [ABSTRACT FROM AUTHOR]

A signal-off type photoelectrochemical (PEC) immunosensor based on Ru(bpy) 3 2+ and Bi 2 S 3 co-sensitized ZnTiO 3 /TiO 2 polyhedra as matrix and SiO 2 /PDA-Au as the label of second antibody was proposed for the ultrasensitive detection of procalcitonin (PCT). The hollow ZnTiO 3 /TiO 2 polyhedra called zinc titanium composite hollow structures (ZTCHS) was prepared by hydrothermal method to enhance the utilization of visible light comparing with pure ZnTiO 3 or TiO 2. The unique structure endowed large specific surface areas and satisfying load capacity to ZTCHS. Ru(bpy) 3 2+ and Bi 2 S 3 were utilized to co-sensitize ZTCHS to further strengthen the PEC performance of ZTCHS. It was interesting that the dual-inhibition effects of SiO 2 /PDA-Au further enhanced the sensitivity of proposed PEC immunosensor. On the one hand, the steric hindrance of SiO 2 /PDA effectively restricted electron transfer. On the other hand, Au nanoparticles could absorb visible light to compete with the matrix material. Based on the above aspects, the proposed signal-off type PEC immunosensor possessed a wide linear range from 0.0001 ng mL−1 to 100 ng mL−1 and low detection limit (about 0.03 pg mL−1, S/N = 3), demonstrating the promising application of PEC immunosensor in analysis fields. ► Novel Ru (bpy) 3 2+ and Bi 2 S 3 sensitized ZTCHS polyhedra shows excellent PEC activity. ► The dual-inhibition effects of SiO 2 /PDA-Au reduce distinctly the photocurrent. ► A signal-off type PEC sensor achieves the ultrasensitive detection of procalcitonin. [ABSTRACT FROM AUTHOR]