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Biofilm plays an important role on microbial corrosion and biofouling in marine environments. Inhibiting biofilm formation on construction surfaces is of great importance. Photocatalytic material with visible-light response, especially BiVO4, is regarded as a promising material for biofilm inhibition due to its green biocidal effect and high antibacterial efficiency. Approaches which can immobilize the photocatalytic particles onto metal surfaces with high mechanical strength are requisite. In this study, zinc matrixes were served as carriers for BiVO4 particles. The BiVO4-inserted zinc matrixes were successfully obtained by ultrasound assisted electrodeposition. The insertion content of BiVO4 showed positive correlation with ultrasound power. Highly enhanced biofilm inhibition properties were obtained by BiVO4 inserted zinc matrixes with an over 95 % decreased bacterial coverage. It was proved that O2− (chief) and OH (subordinate) radicals were responsible for the high biocidal performance. Possible antibacterial mechanism was proposed, indicating that the photoinduced holes would both attack zinc crystals to generate active electrons to form O2− radicals, and react with H2O to generate OH, finally. Furthermore, corrosion resistance of the matrixes was proved to be stable due to the insertion of BiVO4. This study provides a potential application for photocatalyst in marine antifouling and anti-biocorrosion aspects.

Microbiologically influenced corrosion caused by sulfate-reducing bacteria (SRB) poses a serious threat to marine engineering facilities. This study focused on the interaction between the corrosion behavior of two aluminum alloys and SRB metabolic activity. SRB growth curve and sulfate variation with and with aluminum were performed to find the effect of two aluminum alloys on SRB metabolic activity. Corrosion of 5052 aluminum alloy and Al-Zn-In-Cd aluminum alloy with and without SRB were performed. The results showed that both the presence of 5052 and Al-Zn-In-Cd aluminum alloy promoted SRB metabolic activity, with the Al-Zn-In-Cd aluminum alloy having a smaller promotion effect compared with 5052 aluminum alloy. The electrochemical results suggested that the corrosion of the Al-Zn-In-Cd aluminum alloy was accelerated substantially by SRB. Moreover, SRB led to the transformation of Al-Zn-In-Cd aluminum alloy corrosion product from Al(OH)3 to Al2S3 and NaAlO2.

Graphitic carbon nitride (g-C3N4), as a novel carbon material, has gained widespread attention during the last years. Although the g-C3N4 can be synthesized by utilizing various N-rich precursors, the photocatalytic performance of the derived g-C3N4 significantly alters depending on the type of used precursor. In our study, we choose economical urea, dicyandiamide, and melamine as precursors to prepare g-C3N4 under the wrap with tin foil, which are labeled as g-C3N4-U, g-C3N4-D, and g-C3N4-M, respectively. The sizes of g-C3N4-U, g-C3N4-D, and g-C3N4-M are about 2 μm, 4 μm, and 3 μm, and the thickness of them is around 8 nm, 15 nm, and 15 nm, respectively. We find that the g-C3N4-U exhibits the best photocatalytic degradation effect towards Rhodamine B (RhB) among the synthesized g-C3N4 samples. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), atomic force microscopy (AFM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible diffuse reflectance spectra (UV-visible DRS), photoluminescence (PL) spectra, electrochemical measurements, N2 adsorption-desorption isotherms, and electron spin resonance (ESR) are used to study the characteristics of the prepared g-C3N4 samples. It is found that the thinner mesoporous nanostructure of g-C3N4-U results in enhanced separation efficiency of the photo-induced carriers as well as effective utilization of the superoxide radical ( $$ \cdotp {\mathrm{O}}_2^{-} $$ ), which improved the catalytic performance of g-C3N4-U.

Four kinds of Ag3PO4 materials were prepared by controlling the experimental conditions, which were developed as oxidase mimics. Experimental results showed that different synthesis methods led to distinct crystal structures, morphologies, and surface properties, which contributed to diverse oxidase-like activities of Ag3PO4 materials. Among them, Ag3PO4 microcubes (APMCs) can efficiently catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine in the presence of dissolved oxygen to form a blue-colored oxide, presenting the best intrinsic oxidase mimetic ability. The higher-energy [110] facets with more oxygen vacancies exposed and more active sites coupled with more negative charge and larger specific surface area of APMCs contributed to its enhanced oxidase mimetic performance. Besides, mercury ions were proved to remarkably and selectively stimulate the oxidase-like ability of APMCs owing to the formation of Ag–Hg amalgam on its surface. Based on the stimulating effect of Hg2+ towards APMCs, a simple and rapid method for colorimetric determination of Hg2+ was thus established via the significant signal amplification and megascopic color variation. Under the optimal conditions, the sensing system showed a good linear relationship ranging from 0.1 to 7.0 μM and a detection limit of 20 nM for Hg2+, exhibiting high selectivity and good colour stability. Moreover, the colorimetric method was successfully applied to determine Hg2+ in real water samples. Considering these advantages, the developed colorimetric sensing system is expected to hold bright prospects for trace determination of Hg2+ in biological, environmental, and food samples.

Zn coatings are widely applied due to their low cost and negative potential in steel construction and reinforcing steel bars in concretes. However, Zn coatings have been found to perform unsatisfactorily in moist and alkaline environments. In the aqueous alkali environments that inevitably form when concretes fail, galvanized reinforcing steel bars have extremely low corrosion resistance and, consequently, are subject to corrosion. Facing these problems, various additives, including organic and inorganic compounds, have been introduced into Zn coatings to obtain enhanced corrosion resistance, with fewer experiments focusing on organometallic compound composited coatings. As a typical organometallic compound, ferrocene possesses high resistance to corrosive media, such as acids and alkalis. This makes ferrocene an extremely appropriate additive for composite Zn coatings. In this study, Zn-Ferrocene composite coatings were synthesized via electrodeposition with ultrasound assistance. Ferrocene was successfully incorporated using electrochemical control, with a maximum ferrocene content determined to be 19.4% of the C present in the composite coating. The surface morphologies and crystalline structures of the resultant coatings were significantly altered to thin, flake-like hexagonal crystals, a characteristic that was associated with the electrodepositing atomic matrix. The addition of ferrocene greatly improved the wear resistance of the composite coatings, with a 25% mass loss of pure zinc within the coating. The best properties were obtained at an ultrasound assistance level of 15 W. In addition, the corrosion mechanism of the composite coatings was studied at the molecular level. It was found that the corrosion resistance of the composite coatings in alkaline solutions was noticeably enhanced, with an Rct value doubled showing the charge transfer process was inhibited. These results indicate that ultrasound-assisted Zn-Ferrocene composite coatings hold much promise for their potential use in reinforced steel bars in concretes and other abrasive environments.

Sulfate-reducing bacteria (SRB) are a major bacterial group involved in microbiologically influenced corrosion. The interaction between SRB and metals had been the focus of numerous investigations. In this paper, the interaction between SRB and 5052 aluminum alloy was studied using biological and electrochemical methods. Electrochemical analysis suggested that the corrosion rate of the aluminum alloy was accelerated substantially by SRB. This effect was based on the consumption of hydrogen, which in return promoted SRB metabolic activity. Deeper and larger micropits were found on alloy surfaces immersed in SRB. Energy dispersive spectroscopy analyses demonstrated that the concentration of Al on the surface of samples immersed with SRB was lower, while the concentrations of C, O, and S were higher than those without SRB. The results give an insight into clarifying the interaction between SRB and Al.

The present research seeks to address biologically influenced corrosion by electrodepositing a novel 4,5dichloro-2-n-octyl-4-isothiazolin-3-one(DCOIT)-zinc composite films for enhanced corrosion resistant properties. Investigated by electrochemical methods, energy dispersive spectroscopy distribution mapping, and infrared absorption spectroscopy, a deposition mechanism was proposed wherein the DCOIT molecule chelated the zinc ion to participate in electrodeposition. The DCOIT-zinc chelate produced obvious alterations in the surface morphology and crystal orientations. Thermogravimetric analysis determined the DCOIT mass fraction in the composite film was 5%. The DCOIT-zinc composite film demonstrated uniform corrosion in natural seawater and the enhanced anticorrosion property was achieved by successfully embedding DCOIT. (C)2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

In this study, novel Z-scheme MoS2/Bi2WO6 (MB) heterostructured hierarchical flower-like microspheres were successfully prepared via an in-situ growth method on exfoliated MoS2 nanosheets. Experimental results indicated that the content of MoS2 played a key role in controlling the morphology and photocatalytic activity of MB heterostructures. MB-9 exhibited a highly enhanced photocatalytic activity under visible light irradiation compared to pure MoS2, Bi2WO6 and other MB composites, which can be ascribed to the stable Z-scheme heterostructure, leading to the efficient transfer and the separation of photoinduced electrons and holes. The photocatalytic degradation efficiency of rhodamine B (RhB) can reach 100% within 90 min and almost all of Pseudomonas aeruginosa (P. aeruginosa) can be killed after 60 min by MB-9. In addition, MB-9 displayed a nice stability during the photocatalytic process, which favored a long-term use. Moreover, a possible photocatalytic mechanism was proposed based on the active species trapping experiments and electron spin resonance (ESR) tests, verifying that the photogenerated holes (h+) and ⋅O2− radicals were the dominating active species, which followed the Z-scheme reaction mechanism. It is hoped that this work can provide valuable information on developing novel Z-scheme heterostructures with enhanced photocatalytic activities for potential environmental purification and energy conversion.

In the paper, a novel BiOI/MoS2 (BMS) heterojunction was prepared by a facile hydrothermal method. BiOI nanoplates grew in-situ on the surface of exfoliated MoS2 nanosheets, followed by anisotropic growth and self-assembly, forming a hierarchical flower-like heterostructure finally. Experimental results illustrated that MoS2 as well as the BiOI amounts play a vital role in influencing the morphology and photocatalytic activity of BMS heterojunctions. Among the obtained photocatalysts, BMS-8 displayed the strongest photocatalytic performance under visible light irradiation towards the degradation of rhodamine B (RhB) and disinfection of Pseudomonas aeruginosa (P. aeruginosa). The highly enhanced photocatalytic activity can be attributed to the synergistic effect and formation of a type II heterostructure between BiOI and MoS2, boosting the catalytic active sites, enhancing visible light harvesting, and promoting the efficient separation of photoinduced charge carriers. Moreover, BMS-8 composite showed a good stability in photocatalytic reaction, which favored a long-term use. The active species trapping experiments validated the dominating role of photogenerated holes (h+) and ⋅O2− radicals in the photocatalytic process for BMS-8 heterojunction. It is anticipated that this work can promote further interest in constructing novel heterostructures with controllable morphology and highly efficient photocatalytic activity for potential environmental purification and energy conversion.

Developing environmental and cost-effective antifouling technologies is essential to solve serious biofouling problems. Recently, enzyme mimics and halogenating enzymes have caught progressively attention as valuable tools to combat biofilm formation. In this work, the core-shell structure of CeO2@C, as one effective haloperoxidase-like enzyme mimics, was successfully synthesized using the carbon sphere as template through a simple coprecipitation method. Through the UV–vis absorption spectra and kinetic measurements, the CeO2@C displays intrinsic haloperoxidase-like activity via catalyzing the bromination of organic signaling compounds. Meanwhile, the prepared CeO2@C catalyst process high catalytic stability and recyclability, corresponding to a well catalytic performance repeatability after refresh of raw substrates (at least 10 times). The antibactrial property of CeO2@C as haloperoxidase mimicry is evaluated by immersing titanium plate/CeO2@C modified titanium plates into bacterial suspensions with different conditions for 4 h at 37 °C. It can catalyze the oxidation of Br− with H2O2 to the corresponding hypobromous acid (HBrO), which exhibits strong antibacterial activity against Gram-negative (Escherichia coli), Gram-positive (Staphylococcus aureus) bacteria and typical marine (Pseudomonas aeruginosa) bacteria. This study introduces a stable, non-poisonous and inexpensive biomimetic material for antibacterial, antifouling and disinfection applications based on novel sustainable and conservation methods.

In this paper, nanoparticles decorated Ce2(WO4)3 nanosheets (CWNSs) with negative potential and large specific surface area were synthesized and developed as highly efficient peroxidase mimics for colorimetric detection of H2O2. CWNSs can efficiently catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 to induce an obvious color variation. Kinetic analysis indicated that the catalytic behaviors of CWNSs obey the typical Michaelis-Menten mechanism. The peroxidase-like catalytic mechanism of CWNSs was proposed according to the active species trapping experiments, verifying that ·O2– radicals played primary roles in the catalytic reaction. Based on the strong and stable peroxidase-like catalytic activity of CWNSs, a simple, rapid, selective, and ultrasensitive method was successfully established for colorimetric detection of H2O2. The method has a good linear response ranging from 0.5 μM to 100 μM for H2O2 concentration with a lower detection limit of 0.15 μM. Benefitting from the sensitive response and good stability, the method is applied in real sample detection and shows a favorable reproducibility and feasibility. This work not only provides a novel enzymatic mimics with remarkable catalytic activities for biomedical and environmental analysis, but also extends the application area of Ce2(WO4)3 materials.

In this paper, four kinds of Ag2WO4 materials were synthesized via facile hydrothermal methods, which were developed as highly efficient biomimetic catalysts for the first time. These Ag2WO4 materials exhibited distinct oxidase-like activities owing to their different crystal structures, morphologies and surface properties. Among them, Ag@Ag2WO4 nanorods (AWNRs-9) exhibited the best intrinsic oxidase mimetic performance, which were composed of Ag nanoparticles (NPs) loading on the surface of Ag2WO4 nanorods (NRs). It is found that the introduction of Ag NPs can significantly enhanced the oxidase-like catalytic activity due to the synergistic effect between Ag NPs and Ag2WO4 NRs. In addition, the catalytic oxidation reaction of 3,3′,5,5′-tetramethylbenzidine by AWNRs-9 was dramatically and selectively enhanced due to the mercury-stimulated effect. Thus, a simple, rapid and sensitive method for colorimetric detection of Hg2+ was developed, displaying a good linear response in the range of 0.25 μM to 8.0 μM with a detection limit of 1.6 nM. This assay method also showed a high selectivity, good stability and favorable practicability. It was successfully applied to the detection of Hg2+ in real water samples. This sensing system is expected to hold bright prospects for quantitative detection of Hg2+ in biological, environmental, and food fields.

The electrochemical synthesis of hydrogen peroxide (H2O2) based on 2-electron oxygen reduction reaction (ORR), is a particularly promising alternative route for in-situ application. Herein, we prepared the oxidized graphene aerogel supported cubic manganese carbonate composites (GOx/MnCO3) with different GO and MnCO3 ratio through a simple co-precipitation/in-situ coating method. The GOx/MnCO3 composites, with uniformly wrapping of GO on the surface of MnCO3 cubic, display high conductivity and abundant catalytic sites for 2-electron ORR. The G0.2M shows the best ORR catalytic performance, onset potential of 0.635 VRHE, high H2O2 production selectivity and high stability in 3.5% NaCl electrolyte. Based on this, G0.2M as oxygen reduction electrocatalyst, has good antibacterial effect at 0.55 VRHE on the stainless-steel. The antibacterial mechanism is mainly due to the electrocatalytic oxygen reaction of H2O2 and the side reaction of •OH and O2•-. This provides an impressive, effective and environmentally friendly electrochemical approach for antibacterial and antifouling applications.

Various 3-dimensional C/CeO2 hollow nanostructure frameworks (3D C/CeO2 HNFs) were synthesized by using a polymer blowing process that is accelerated by adding a certain amount of cerium nitrate. Polyvinylpyrrolidone was used as the polymer. The resulting HNFs were characterized by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. The HNFs possess a large specific surface area, and the CeO2 nanocrystals consist of a single phase. The HNFs display intrinsic peroxidase-like activity and can catalyze the oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine in the presence of H2O2 to produce a blue product. The method was applied to the quantification of H2O2 with a 5.2 nM detection limit. The analytical range is from 10 nM to 1 μM.

Zinc electrodeposits are one of the most popular safeguard procedures for steel constructions. However, in natural aquatic environments, especially marine environments, zinc electrodeposits suffer significantly from microbial induced corrosion and biofouling which lead to metal failure. To better confront the microbial induced problems, a biocide-zinc electrodeposit was synthesized based on chelating action. In this paper, nontoxic and biocidal natural polysaccharide, chitosan, was successfully incorporated into the zinc electrodeposit matrix, synthesizing a kind of chitosan–zinc composite electrodeposit. The addition of chitosan in the electrolyte influenced the surface morphology and crystalline structure of the resultant electrodeposits significantly, while a chitosan–zinc chelation complex was also found in the electrodeposits. A synthesis model was proposed in which a chitosan molecule could chelate zinc ions in the electrolyte by means of its N atoms in amino groups and O atoms in hydroxide radicals, which promoted the codeposition of zinc and chitosan during synthesis. Furthermore, remarkably enhanced broad-spectrum bactericidal properties of the chitosan–zinc electrodeposits were revealed through Escherichia coli, Pseudomonas aeruginosa and Shewanella oneidensis exposure. The best antibacterial properties of the resultant electrodeposits were obtained when the chitosan concentration was 0.6 g L−1 in the electrolyte.

Correction for ‘Effect of graphene oxide on anticorrosion performance of polyelectrolyte multilayer for 2A12 aluminum alloy substrates’ by Xia Zhao et al., RSC Adv., 2017, 7, 33764–33774.