Double enzyme mimetic activities of multifunctional Ag nanoparticle-decorated Co_(3)V_(2)O_(8)hollow hexagonal prismatic pencils for application in colorimetric sensors and disinfection

Since the catalytic activity of most nanozymes is still far lower than the corresponding natural enzymes,there is urgent need to discover novel highly efficient enzyme-like materials.In this work,Co_(3)V_(2)O_(8)with hollow hexagonal prismatic pencil structures were prepared as novel artificial enzyme mimics.They were then decorated by photo-depositing Ag nanoparticles(Ag NPs)on the surface to further improve its catalytic activities.The Ag NPs decorated Co_(3)V_(2)O_(8)(ACVPs)showed both excellent oxidase-and peroxidase-like catalytic activities.They can oxidize the colorless 3,3’,5,5’-tetramethylbenzidine rapidly to induce a blue change.The enhanced enzyme mimetic activities can be attributed to the surface plasma resonance(SPR)effect of Ag NPs as well as the synergistic catalytic effect between Ag NPs and Co_(3)V_(2)O_(8),accelerating electron transfer and promoting the catalytic process.ACVPs were applied in constructing a colorimetric sensor,validating the occurrence of the Fenton reaction,and disinfection,presenting favorable catalytic performance.The enzyme-like catalytic mechanism was studied,indicating the chief role of⋅O_(2)-radicals in the catalytic process.This work not only discovers a novel functional material with double enzyme mimetic activity but also provides a new insight into exploiting artificial enzyme mimics with highly efficient catalytic ability.

Developing high photocatalytic antibacterial Zn electrodeposited coatings through Schottky junction with Fe3+-doped alkalized g-C_(3)N_(4) photocatalysts

Pure Zn coatings easily lose their protective performance after biofouling because they have no antibacterial effect under visible light.In this study,we fabricate a new antibacterial Zn composite coating using electrodeposition to couple Fe3+-doped alkalized g-C_(3)N_(4)(AKCN-Fe)into an existing Zn coating and show that the AKCN-Fe enhances antibacterial property of the Zn coating under visible light.We attribute this enhancement to the high photocatalytic performance,high loading content,and good dispersion of AKCN-Fe.In addition,the photocatalytic antibacterial mechanism of the composite coating is supported by scavenger experiments and electron paramagnetic resonance(EPR)measurements,suggesting that superoxide(·O_(2)^(-))and hydroxyl radical(·OH)play main and secondary roles,respectively.

In-situ topotactic construction of novel rod-like Bi_(2)S_(3)/Bi_(5)O_(7)I p-n heterojunctions with highly enhanced photocatalytic activities

In this work,a novel Bi_(2)S_(3)/Bi_(5)O_(7)I p-n heterojunction with three-dimensional rod-like nanostructure was successfully constructed through an in-situ topotactic ion exchange approach.A possible evolution mech-anism from Bi_(5)O_(7)I nanobelts(NBs)into Bi_(2)S_(3)/Bi_(5)O_(7)I rod-like heterostructures(BSI RHs)was proposed,depicting the self-assembly process of internal Bi_(5)O_(7)I NBs and outside networks interwoven by Bi_(2)S_(3)nanorods(NRs),which abided by the Ostwald ripening and epitaxial growth.Owing to the formation of p-n heterojunction and rich oxygen vacancies(OVs),the visible-light absorption ability and separation of photogenerated charge carriers of BSI RHs were highly promoted,leading to a greatly improved photocatalytic ability than that of Bi_(2)S_(3)and Bi_(5)O_(7)I.BSI-1 exhibited the strongest photocatalytic performance,and almost all rhodamine B(RhB)and Pseudomonas aeruginosa(P.aeruginosa)can be thoroughly removed within 90 min.Moreover,a possible photocatalytic mechanism of BSI RHs was proposed based on the tests of active species trapping,electron spin resonance(ESR),photoelectrochemistry(PEC),and photoluminescence(PL)combined with the density functional theory(DFT)simulated computation,vali-dating the dominating roles of·O_(2)^(−)and h+during the photocatalytic process.This work is expected to motivate further efforts for developing novel heterostructures with highly efficient photocatalytic performances,which presents a promising application prospect in the fields of energy and environment.

1D Bi_(2)S_(3) nanorods modified 2D BiOI nanoplates for highly efficient photocatalytic activity:Pivotal roles of oxygen vacancies and Z-scheme heterojunction

In this study,a novel Bi_(2)S_(3)/BiOI Z-scheme photocatalyst with 3D porous hierarchical network-like heterostructure(BSBI NHs)and rich oxygen vacancies(OVs)was fabricated by a facile ion exchange method followed by the in-situ growth process.A possible formation mechanism of BSBI NHs was studied,showing the self-assembled process of in-situ interwoven growth of 1D Bi_(2)S_(3) nanorods(NRs)on the surface of 2D BiOI disk-like nanoplates(NPs),which followed the Ostwald ripening and epitaxial growth.The modification of BiOI NPs by Bi_(2)S_(3) NRs brought about the formation of Z-scheme heterojunction and massive OVs,which improved the visible-light response property and promoted the separation of photoexcited charge carriers of BSBI NHs.BSBI NHs exhibited a significantly enhanced photocatalytic activity compared with Bi_(2)S_(3) and BiOI,and BSBI-1 can remove almost all bacteria and Rhodamine B(RhB)after 60 min visible light illumination.In addition,the photocatalytic mechanism was studied and speculated based on the tests of active species capture,electron spin resonance(ESR),and density functional theory(DFT)simulation calculation,proving the primary roles of·OH,·O_(2)^(-)and h^(+)during the photocatalytic reaction.This work provides new insights into the design and exploitation of novel heterojunctions with highly efficient photocatalytic performances for environmental remediation applications.

Green synthesis of functional metallic nanoparticles by dissimilatory metal-reducing bacteria“Shewanella”:A comprehensive review

The biosynthesis strategy of nanoparticles has attracted much attention due to the mild synthesis condi-tions,environmental-friendly properties,and low costs.Biosynthesized nanoparticles(bio-NPs)not only show excellent physicochemical properties,but also exhibit high stability,enlarged specific surface area,and excellent biocompatibility,which are crucial for industrial,agricultural,and medical fields.She-wanella,a kind of dissimilatory metal-reducing bacteria,is regarded as a typical biosynthesis-functional bacteria class with wide distribution and strong adaptability.Thus,in this paper,functional bio-NPs by Shewanella were reviewed to provide a comprehensive view of current research progress.The biosynthetic mechanisms of Shewanella are summarized as the Mtr pathway(predominant),extracellular polymeric substance-induced pathway,and enzyme/protein-induced pathway.During the biosynthesis process,bio-logical factors along with the physicochemical parameters highly influenced the properties of the resul-tant bio-NPs.Till now,bio-NPs have been applied in various fields including environmental remediation,antibacterial applications,and microbial fuel cells.However,some challenging issues of bio-NPs by She-wanella remain unsolved,such as optimizing suitable bacterial strains,intelligently controlling bio-NPs,clarifying biosynthesis mechanisms,and expanding bio-NPs applications.

Interaction between sulfate-reducing bacteria and aluminum alloys——Corrosion mechanisms of 5052 and Al-Zn-In-Cd aluminum alloys

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 Al2 S3 and NaAlO2.

Antifouling nanocomposite polymer coatings for marine applications:A review on experiments,mechanisms,and theoretical studies

Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating fouling in the marine environment.Meanwhile,nanocomposite polymer coatings are a novel generation of antifouling coatings with merits of toxin-free chemical composition and ease of large-scale application.Nanomaterials such as nano-metals,nano-metal oxides,metal-organic frameworks,carbon-based nanostructures,MXene,and nanoclays have antibacterial and antifouling properties in the polymer coatings.Besides,these nanomaterials can improve the corrosion resistance,mechanical strength,weathering stability,and thermal resistance of the polymer coatings.Therefore,in this review paper,the antifouling nanocomposite coatings are introduced and antifouling mechanisms are discussed.This review explicitly indicates that the antifouling efficiency of the nanocomposite coatings depends on the properties of the polymer matrix,the inherent properties of the nanomaterials,the weight percent and the dispersion method of the nanomaterials within the coating matrix,and the chemicals used for modifying the surface of the nanomaterials;meanwhile,the hybrids of different nanomaterials and appropriate chemical agents could be used to improve the antifouling behavior of the prepared nanocomposites.Moreover,the theoretical studies are introduced to pave the way of researchers working on theantifouling coatings,and the importance of the theoretical studies and computational modeling along with the experimental research is notified to develop antifouling coatings with high efficiency.

Biofilm inhibition mechanism of BiVO inserted zinc matrix in marine isolated bacteria

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 visiblelight response,especially BiVO_(4),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 BiVO_(4)particles.The BiVO_(4)-inserted zinc matrixes were successfully obtained by ultrasound assisted electrodeposition.The insertion content of BiVO_(4)showed positive correlation with ultrasound power.Highly enhanced biofilm inhibition properties were obtained by BiVO_(4)inserted zinc·matrixes with an over 95%decreased bacterial coverage.It was proved that O2-(chief)andOH(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 H2 O to generate·OH,finally.Furthermore,corrosion resistance of the matrixes was proved to be stable due to the insertion of BiVO_(4).This study provides a potential application for photocatalyst in marine antifouling and anti-biocorrosion aspects.