•Basic bismuth nitrate precursor films were fabricated via an in situ growth route.•The calcination can transform the precursor film to β-Bi2O3 films.•β-Bi2O3 films have stable photoinduced current and excellent cyclic stability.•β-Bi2O3 films have great potential use in energy, environment, and antifouling.Photoactive β-Bi2O3 films with oriented microstructure are fabricated by calcination of basic bismuth nitrate precursor films on the Cu surface synthesized using in situ growth method. The crystal structure and morphology can be tailored by controlling the calcination temperature. The β-Bi2O3 film heated at 550 °C has a stable highest photoinduced current density of −0.35 mA/cm2 at a −0.40 V applied bias versus Ag/AgCl and excellent cyclic stability. This long-term stability of the β-Bi2O3 film is benefiting from its chemical and crystal stability. Therefore, β-Bi2O3 films fabricated using this strategy have great potential use of energy conversion, environment protection and biofouling control.β-Bi2O3 films with tunable photoelectrochemical property and oriented microstructure are fabricated by calcination of basic bismuth nitrate precursor films on the Cu surface synthesized using in situ growth method.Download high-res image (165KB)Download full-size image

Microbially influenced corrosion (MIC) accelerates the failure of metal in a marine environment. In this research, slippery lubricant-infused porous surface (SLIPS) was designed on aluminum, and its great potential for inhibiting MIC induced by sulfate-reducing bacteria (SRB) was demonstrated in a simulated marine environment. The inhibition mechanism of SLIPS to MIC was proposed based on its effective roles in the suppression of SRB settlement and isolation effect to corrosive metabolites. The liquid-like property is demonstrated to be the major contributor to the suppression effect of SLIPS to SRB settlement. The effects of environmental factors (static and dynamic conditions) and lubricant type to SRB settlement over SLIPS were also investigated. It was indicated that the as-fabricated SLIPS can inhibit the SRB settlement in both static and dynamic marine conditions, and lubricant type presents a negligible effect on the SRB settlement. These results will provide a series of foundational data for the future practical application of SLIPS in the marine environment, and also a lubricant selecting instruction to construct SLIPS for MIC control.Keywords: aluminum; interfaces; microbially influenced corrosion; slippery lubricant-infused porous surfaces; sulfate-reducing bacteria

In this study, a novel visible-light-sensitive Bi2WO6/BiVO4 composite photocatalyst was controllably synthesized through a facile one-pot hydrothermal method. The Bi2WO6/BiVO4 composite exhibited a perfect nest-like hierarchical microsphere structure, which was constructed by the self-assembly of nanoplates with the assistance of polyvinylpyrrolidone (PVP). The growth mechanism of the Bi2WO6/BiVO4 composite and the effect of its structure on its photocatalytic performance was investigated and proposed. Experimental results showed that the Bi2WO6/BiVO4 composites displayed enhanced photocatalytic antifouling activities under visible light irradiation compared to pure Bi2WO6 and BiVO4. Bi2WO6/BiVO4-1 exhibited the best photocatalytic antifouling performance, and almost all (99.99%) Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria were killed within 30 min. Moreover, the Bi2WO6/BiVO4-1 composite exhibited excellent stability and reusability in the cycled experiments. The photocatalytic antifouling mechanism was proposed based on the active species trapping experiments, revealing that the photo-induced holes (h+) and hydroxyl radicals (˙OH) could attack the cell wall and cytoplasmic membrane directly and lead to the death of bacteria. The obviously enhanced photocatalytic activity of the Bi2WO6/BiVO4-1 composite could be mainly attributed to the formation of heterojunctions, accelerating the separation of photo-induced electrons and holes. Furthermore, the large BET surface area combined with the wide photoabsorption region further improved the photocatalytic performance of the Bi2WO6/BiVO4-1 composite. This study provides a new strategy to develop novel composite photocatalysts with enhanced photocatalytic performance for marine antifouling and water purification.

•Slippery liquid-infused porous surfaces (SLIPS) were fabricated over aluminum.•SLIPS depress the adherence of sulfate reducing bacteria in static seawater.•SLIPS inhibit the microbiological corrosion of aluminum in static seawater.•The possible microbiological corrosion protection mechanism of SLIPS is proposed.Microbiological corrosion induced by sulfate reducing bacteria (SRB) is one of the main threatens to the safety of marine structure. To reduce microbiological corrosion, slippery liquid infused porous surfaces (SLIPS) were designed and fabricated on aluminum substrate by constructing rough aluminum oxide layer, followed by fluorination of the rough layer and infiltration with lubricant. The as-fabricated SLIPS were characterized with wettability measurement, SEM and XPS. Their resistances to microbiological corrosion induced by SRB were evaluated with fluorescence microscopy and electrochemical measurement. It was demonstrated that they present high resistance to bacteria adherence and the resultant microbiological corrosion in static seawater.

•SLIPS was designed over aluminum for marine anti-biofouling application.•The micro-structure with a low length scale is important for designing stable SLIPS.•The liquid-like property contributes to the exceptional anti-biofouling property of SLIPS.•The low roughness facilitates removing settled algae from SLIPS under shear force.Marine biofouling, caused by the adhesion of microorganism, is a worldwide problem in marine systems. In this research work, slippery liquid-infused porous surface (SLIPS), inspired by Nepenthes pitcher plant, was constructed over aluminum for marine anti-biofouling application. The as-fabricated SLIPS was characterized with SEM, AFM, and contact angle meter. Its anti-biofouling performance was evaluated with settlement experiment of a typical marine biofouling organism Chlorella vulgaris in both static and dynamic conditions. The effect of solid substrate micro-structure on anti-biofouling property of SLIPS was studied. It was suggested that the micro-structure with low length scale and high degree of regularity should be considered for designing stable SLIPS with exceptional anti-biofouling property. The liquid-like property is proven to be the main contributor for the exceptional anti-biofouling performance of SLIPS in both static and dynamic conditions. The low roughness, which facilitates removing the settled C. vulgaris under shear force, is also a main contributor for the anti-biofouling performance of SLIPS in dynamic condition.

•Metal-complex film with super-hydrophobic property was prepared on Cu surface.•Morphology-controllable synthesis of metal-complex film is realized.•Dissolution–coordination–precipitation model is used to illuminate film formation.•Mechanism for high corrosion resistance of super-hydrophobic film is clarified.Metal-complex film with super-hydrophobic property is fabricated on copper (Cu) surface with one-step electrochemical method in laurylamine/ethanol solution. “Dissolution–coordination–precipitation” model is proposed to illuminate formation mechanism of Cu(II)-laurylamine complex film. The super-hydrophobic film can act as a barrier to corrosion of underlying copper with inhibition efficiency close to 100%, and it maintains stability within a wide potential range. The origin of such corrosion protection property is explained from view point that hierarchical micro-structure of the super-hydrophobic film can maintain a stable air/liquid interface which inhibits erosion of corrosive medium.

•This work provided a new and facile approach to construct stable signal amplification system based on dopamine polymerization.•Dopamine polymerization process was enhanced in the presence of Fe3O4@MnO2 nanoplates owing to the strong oxidative nature of MnO2.•Various kinds of bio-recognizing and signaling molecules could be immobilized for different detection requirements.In this work, a facile approach to design versatile signal amplification system for bacterial detection has been presented. Bio-recognition elements and signaling molecules can be immobilized on the surface of Fe3O4@MnO2 nanomaterials with the help of bioinspired polydopamine (PDA). Fe3O4@MnO2 nanoplates were chosen as carrier for bio-recognizing and signaling molecules because this kind of nanomaterial was superparamagnetic and the existence of MnO2 could enhance the polymerization of dopamine due to its strong oxidative ability. This nanocomposite system was versatile because PDA around Fe3O4@MnO2 nanoplates provided a stable and convenient platform for immobilization of biological and chemical materials, and various kinds of bio-recognizing and signaling molecules could be immobilized by reaction with pendant amino groups of dopamine to meet different detection requirements. Since a substantial amount of signaling molecules were immobilized on the surface of the nanocomposites, so the sensitivity of detection would be improved when the prepared nanocomposites were selectively conjugated with target pathogen. In the experimental section, a sandwich-type electrochemical biosensor was developed to verify the amplified bacterial detection sensitivity. Concanavalin A (conA) and ferrocene (Fc) were chosen as bio-recognition elements and signaling molecules for detection of Desulforibrio caledoiensis, respectively. The conA and Fc modified nanocomposites were conjugated on electrode by the selective recognition between conA and target bacteria, and the bacterial population was obtained by quantification of the electrochemical signal of Fc moieties. The experimental results showed that the detection sensitivity for D. caledoiensis was improved by taking advantage of this signal amplification system.

This work presents the synthesis of bacteria-mediated bioimprinted films for selective bacterial detection. Marine pathogen sulfate-reducing bacteria (SRB) were chosen as the template bacteria. Chitosan (CS) doped with reduced graphene sheets (RGSs) was electrodeposited on an indium tin oxide electrode, and the resulting RGSs-CS hybrid film served as a platform for bacterial attachment. The electrodeposition conditions were optimized to obtain RGSs-CS hybrid films with excellent electrochemical performance. A layer of nonconductive CS film was deposited to embed the pathogen, and acetone was used to wash away the bacterial templates. Electrochemical impedance spectroscopy was performed to characterize the stepwise modification process and monitor the SRB population. Faradic impedance measurements revealed that the charge transfer resistance (Rct) increased with increased SRB concentration. A linear relationship between ΔRct and the logarithm of SRB concentration was obtained within the concentration range of 1.0×104 cfu mL−1 to 1.0×108 cfu mL−1. The impedimetric sensor showed good selectivity towards SRB based on size and shape. Hence, selectivity for bacterial detection can be improved if the bioimprinting technique is combined with other bio-recognition elements.Highlights► This work presents an impedance biosensor based on bacteria-mediated bioimprinting films for bacterial detection. ► Chitosan doped with graphene has been electrodeposited and served as a platform for bacteria attachment. ► The proposed sensor shows good selectivity based on size and shape differences towards target bacteria.

Nanomaterial-based enzyme-linked immunosorbent assay (ELISA) with sufficient sensing specificity is a useful analytical tool for the detection of toxicologically important substances in complicated biological systems. Increasing worldwide demand for nanomaterials and increasing concern on their safe development and use, require a simple, stable, and sensitive detection assay for pathogen evaluation and environmental monitoring. However, this goal is not yet achieved. A design for a hybrid MnO2 nanowire-ELISA using the sandwich assay format, which provides quantitative binding information for both a specific antibody and the pathogen, sulfate-reducing bacteria, and detects pathogen concentration, is presented. 3,3′,5,5′-Tetramethylbenzidine was used as the substrate and was allowed to react with the MnO2 nanowires without H2O2 in the reaction system. The kinetic parameters were measured with the system acting as a catalytic biosensor. The effectiveness of the MnO2 nanowire-based biosensor was demonstrated by its sensitive detection of the pathogen.Graphical abstractSchematic representation of the detection method for bacteria based on the MnO2-mediated immunoassay combined with ELISA. HRP-mediated ELISA is presented for comparison. A design for a hybrid MnO2 nanowire-ELISA using the sandwich assay format, which provides quantitative binding information for both a specific antibody and the pathogen, sulfate-reducing bacteria, and detects pathogen concentration, is presented.Highlights► Schematic representation for SRB detection based on the MnO2-mediated immunoassay. ► MnO2 nanowire were capable of catalyzing oxidation TMB in the absence of H2O2. ► MnO2-mediated ELISA varied with the SRB concentration from 1.8 × 104 to 1.6 × 107 CFU mL−1

Functionalized graphene oxide (GO) sheets coupled with a signal amplification method based on the nanomaterial-promoted reduction of silver ions for the sensitive and selective detection of bacteria. This paper aims to develop an electrochemical route combined with GO sheet-mediated Ag enhancement for biological/chemical analyte detection. A linear relationship between the stripping response and the logarithm of the bacterial concentration was obtained using an electrochemical technique for concentrations ranging from 1.8 × 102 to 1.8 × 108 cfu mL−1, with a slope of 15.28 and a correlation coefficient of 0.995. Dot blot assay was used as a conventional immunoassay method for comparison with the electrochemical method, as well as to observe the quality of the anti-sulfate-reducing bacteria (SRB) antibody (Ab) used in the immunosensor. The GO sheet-mediated silver enhancement holds great potential for the rapid analysis of protein, DNA, and pathogens.

A facile, sensitive and reliable impedimetric immunosensor doped with reduced graphene sheets (RGSs) and combined with a controllable electrodeposition technique was developed for the selective detection of marine pathogenic sulphate-reducing bacteria (SRB). The morphology of RGSs and the electrochemical properties of RGSs-doped chitosan (CS) nanocomposite film were investigated by atomic force microscopy, Fourier transform infrared spectroscopy, and cyclic voltammetry (CV). Electrochemical impedance spectroscopy and CV were used to verify the stepwise assembly of the sensor system. Faradic impedance spectroscopy for charge transfer for the redox probe Fe(CN)63−/4− was done to determine SRB concentrations. The diameter of the Nyquist diagram that is equal to the charge-transfer resistance (Rct) increased with increasing SRB concentration. A linear relationship between Rct and SRB concentration was obtained in the SRB concentration range of 1.8 × 101 to 1.8 × 107 cfu/ml. The impedimetric biosensor gave a distinct response to SRB, but had no obvious response to Vibrio angillarum. It showed a high selectivity for the detection of the pathogen. Based on a combination of the biocompatibility of CS and good electrical conductivity of RGSs, a nanocomposite film with novel architecture was used to immobilize biological and chemical targets and to develop a new type of biosensor.

A cobalt hydroxide modified glassy carbon (Co(OH)2/GC) electrode has been fabricated by a galvanostatic electrodeposition method. The catalytic activity for the oxygen (O2) reduction reaction (ORR) of this electrode in alkaline media is studied by cyclic voltammetry, rotating disk electrode voltammetry, and rotating ring-disk electrode voltammetry. The O2 reduction at the Co(OH)2/GC disk electrode has been found to undergo an electrochemical process followed by sequential disproportionation of the electrochemical reduction intermediates, i.e., superoxide anion (O2−) and hydrogen peroxide anion (HO2−) in 0.1 M KOH solution. The Co(OH)2 is first found to possess an excellent catalytic activity not only for the disproportionation of the O2− produced into O2 and HO2− but also for that of the HO2− produced, combined with electrochemical reduction of O2 mediated by surface functional groups at the carbon electrode surface. The Co(OH)2 is a potential electrode material for the ORR in alkaline fuel cells and metal–air batteries.

The growth cycle of sulphate-reducing bacteria (SRB), Desulfovibrio caledoniensis, and the effect of SRB on the environmental parameters and corrosion behavior of Q235 steel during a growth cycle in aerobic (air- and O2-saturated culture solutions) and anaerobic (N2− saturated culture solutions) conditions were investigated. Oxygen dissolved in the culture solutions induced slow growth and fast decay of SRB. The growth process of SRB under anaerobic and aerobic conditions influenced sulphide anion concentration (Cs2−)(Cs2−), pH, and conductivity (κ  ). The values of Cs2−Cs2− and κ under aerobic conditions were lower than those under anaerobic conditions, and the pH values increased from O2- to air- to N2-saturated culture solutions. Aerobic conditions induced the open circuit potential (EOC) to shift in the positive direction after the stationary phase of SRB growth. The charge transfer resistance (Rct) increased quickly during the exponential growth phase, almost maintained stability during the stationary phase, and decreased after the stationary phase in all three conditions, and the impedance magnitude decreased from O2- to air- to N2-saturated culture solutions. The biofilms induced by SRB were observed by scanning electron microscopy (SEM) under aerobic and anaerobic conditions, and energy dispersive spectroscopy (EDS) was performed in abiotic and SRB-containing systems to distinguish the corrosion products. The reasons for the effects of SRB on the environmental parameters and corrosion behavior of carbon steel are discussed.

This paper describes the electrochemical properties of reduced graphene sheets (RGSs) for the electrocatalytic properties towards the hydrazine oxidation in alkaline media. The RGSs have been produced in high yield by a soft chemistry route involving graphite oxidation, ultrasonic exfoliation, and chemical reduction. The RGSs possess excellent electrocatalytic activity towards the hydrazine oxidation. In our opinion, RGSs are a potential electrode material for direct hydrazine fuel cells and electrochemical sensors for hydrazine detection.

A 3D-immunosensor based on simple and efficient trapping platform (foam Ni) combining with adsorption of gold nanoparticles and specific recognition of biological/chemical molecular has been reported for detection of sulfate-reducing bacteria (SRB) using electrochemical impedance spectroscopy (EIS). The impedance spectra were also used to characterize the successful construct and stepwise modification of the impedimetric immunosensors. This results show that a linear relationship between electron-transfer resistance (Rct) values and the logarithm of the SRB concentrations was obtained for the SRB concentration range of 2.1 × 101–2.1 × 107 cfu/ml. Additionally, the fabricated immunosensor shows a high selectivity against other bacteria.

Cyclic voltammetry, electrochemical impedance spectroscopy, and rotating disk electrode voltammetry have been used to study the effect of chloride ions on the dissolved oxygen reduction reaction (ORR) on Q235 carbon steel electrode in a 0.02 M calcium hydroxide (Ca(OH)2) solutions imitating the liquid phase in concrete pores. The results indicate that the cathodic process on Q235 carbon steel electrode in oxygen-saturated 0.02 M Ca(OH)2 with different concentrations of chloride ions contain three reactions except hydrogen evolution: dissolved oxygen reduction, the reduction of Fe(III) to Fe(II), and then the reduction of Fe(II) to Fe. The peak potential of ORR shifts to the positive direction as the chloride ion concentration increases. The oxygen molecule adsorption can be inhibited by the chloride ion adsorption, and the rate of ORR decreases as the concentration of chloride ions increases. The mechanism of ORR is changed from 2e− and 4e− reactions, occurring simultaneously, to quietly 4e− reaction with the increasing chloride ion concentration.

A fast, sensitive and reliable quartz crystal microbalance (QCM) biosensor is described for the selective detection of the marine pathogenic sulphate-reducing bacterium (SRB), D. desulfotomaculum. Based on the amplification of the response of vancomycin-functionalised magnetic nanoparticles (Van-mNPs), under an external magnetic field, the bacteria-mNPs conjugates attach to the surface of an Au electrode. The QCM biosensor gave a distinct response to the vancomycin-sensitive, D. desulfotomaculum, but had no obvious response to the vancomycin-resistant bacterium, Vibrio anguillarum. The effects of the optimization conditions such as the incubation time and pH on the detection were also investigated, respectively. Optimised assays showed that the biosensor could obtain the best response with a 30 min incubation of the bacteria with the Van-mNPs. A linear relationship between the QCM response and the logarithm of the bacterial concentration was observed in the range of 1.8 × 104 to 1.8 × 107 cfu/ml. The sensor system has a potential for further applications and provides a facile and sample method for detection of pathogenic bacteria.

A fast, sensitive and reliable potentiometric stripping analysis (PSA) is described for the selective detection of the marine pathogenic sulfate-reducing bacterium (SRB), Desulforibrio caledoiensis. The chemical and electrochemical parameters that exert influence on the deposition and stripping of lead ion, such as deposition potential, deposition time and pH value were carefully studied. The concentration of SRB was determined in acetate buffer solution (pH 5.2) under the optimized condition (deposition potential of −1.3 V, deposition time of 250 s, ionic strength of 0.2 mol L−1 and oxidant mercury (II) concentration of 40 mg L−1). A linear relationship between the stripping response and the logarithm of the bacterial concentration was observed in the range of 2.3 × 10 to 2.3 × 107 cfu mL−1. In addition, the potentiometric stripping technique gave a distinct response to the SRB, but had no obvious response to Escherichia coli. The measurement system has a potential for further applications and provides a facile and sample method for detection of pathogenic bacteria.

The electrochemical impedance spectroscopy (EIS) at different potentials has been used to study the oxygen reduction reaction (ORR) in 3.5% NaCl solution on glassy carbon (GC) electrode in this work. Results show that ORR consists of three two-electron reaction steps and both superoxide ion (O2–) and hydrogen peroxide (H2O2), which are produced by ORR, obstruct the diffusion of oxygen to the surface of the electrode and make the EIS results change into a transmissive finite diffusion process with the real part contraction and a reflective finite diffusion process from a semi-infinite diffusion process. The values of electron transfer resistance (Rt) and diffusion resistance (Rd) were calculated from EIS. O2– influenced strongly on the Rt values and induced a maximum at −0.45 V.

An impedimetric immunosensor was fabricated for rapid and non-labeled detection of sulfate-reducing bacteria, Desulforibrio caledoiensis (SRB) by immobilizing lectin-Concanavalin A using an agglutination assay. The immobilization of lectin was conducted using amine coupling on the surface of a gold (Au) electrode assembled with 11-Mercaptoundecanoic acid. Electrochemical impedance spectroscopy (EIS) was used to verify the stepwise assembly of the sensor system. The work conditions of the impedimetric immunosensor, such as pH of the buffer solutions and the incubation time of lectin, were optimized. Faradic impedance spectra for charge transfer for the redox probe Fe(CN)63−/4−were measured to determine SRB concentrations. The diameter of the Nyquist diagram that is equal to the charge-transfer resistance (Rct) increased with increasing SRB concentration. A linear relationship between Rct and SRB concentration was obtained in SRB concentration range of 1.8 to 1.8 × 107 cfu/ml. The variation of the SRB population during the growth process was also monitored using the impedimetric immunosensor. This approach has great potential for simple, low-cost, and time-saving monitoring of microbial populations.

In this study, a novel visible-light-sensitive Bi2WO6/BiVO4 composite photocatalyst was controllably synthesized through a facile one-pot hydrothermal method. The Bi2WO6/BiVO4 composite exhibited a perfect nest-like hierarchical microsphere structure, which was constructed by the self-assembly of nanoplates with the assistance of polyvinylpyrrolidone (PVP). The growth mechanism of the Bi2WO6/BiVO4 composite and the effect of its structure on its photocatalytic performance was investigated and proposed. Experimental results showed that the Bi2WO6/BiVO4 composites displayed enhanced photocatalytic antifouling activities under visible light irradiation compared to pure Bi2WO6 and BiVO4. Bi2WO6/BiVO4-1 exhibited the best photocatalytic antifouling performance, and almost all (99.99%) Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria were killed within 30 min. Moreover, the Bi2WO6/BiVO4-1 composite exhibited excellent stability and reusability in the cycled experiments. The photocatalytic antifouling mechanism was proposed based on the active species trapping experiments, revealing that the photo-induced holes (h+) and hydroxyl radicals (˙OH) could attack the cell wall and cytoplasmic membrane directly and lead to the death of bacteria. The obviously enhanced photocatalytic activity of the Bi2WO6/BiVO4-1 composite could be mainly attributed to the formation of heterojunctions, accelerating the separation of photo-induced electrons and holes. Furthermore, the large BET surface area combined with the wide photoabsorption region further improved the photocatalytic performance of the Bi2WO6/BiVO4-1 composite. This study provides a new strategy to develop novel composite photocatalysts with enhanced photocatalytic performance for marine antifouling and water purification.